59

ÍNDICE DE AFICHESÍNDICE DE AFICHES

1Félix Román and Aidalú Joubert

LIQUID CHROMATOGRAPHY MASSSPECTROMETRY LABORATORY TO ENHANCEEDUCATION IN FOOD, SOILS ANDENVIRONMENTAL SCIENCES

A8

2

Lizzette A. Rodríguez, I. MatthewWatson, Marie Edmonds, Graham Ryan,Vicky Hards, Clive M.M. Oppenheimer,and Gregg J.S. Bluth

SO2 LOSS RATES IN THE PLUME EMITTED BYSOUFRIÈRE HILLS VOLCANO, MONTSERRATA7

2José R. Rivera Negrón and Maritza DeJesús Echevarría

TRAFFIC DENSITY AND THE CORRELATIONWITH THE DETERMINATION OF TOTALSUSPENDED PARTICLES USING A HIGHVOLUME

A6

1

Marianne Pérez-Bosch, CynthiaCaraballo Alvarez, Ana M. Rivera-López, Belitza A. Brocco-Jaime andMaritza De Jesús Echevarría

THE RAINWATER QUALITY ON THEUNIVERSITY OF PUERTO RICO ATMAYAGÜEZ CAMPUS

A5

2Sorelis Nieto Zambrano, Félix Román,Aidalú Joubert and Oscar Perales Pérez

STUDY OF THE ADSORPTION BEHAVIOR OFTETRACYCLINE ONTO CRUMB RUBBER ANDCARBON BLACK IN AQUEOUS SOLUTION BYLC/MS/MS

A4

1

María Irizarry Montalvo, Ricardo BáezVázquez, Luis Benítez Alicea, DanielConcepción James, Ingrid Padilla, andSangchul Hwang

CHEMISTRY EXPERIENCES INENVIRONMENTAL ENGINEERING PROJECTSTHROUGH THE CLASS INCI 4998:UNDERGRADUATE RESEARCH

A3

2M. A. De Jesús, J. O. Oran, N. Abu-Hatab and M. J. Sepaniak

NANOSTRUCTURED SILVER-POLYMERSUBSTRATES FOR THE SURFACE ENHANCEDRAMAN SCATTERING (SERS) DETECTIONOFTRACE AROMATIC COMPOUNDS

A2

1Anita Crespo Vázquez, VíctorFernández-Alos, José R. Rivera-Negrónand Maritza De Jesús Echevarría

TOTAL SUSPENDED PARTICULATE AT THEUNIVERSITY OF PUERTO RICO MAYAGÜEZCAMPUS CHEMISTRY DEPARTMENT

A1

Track A: Environmental Chemistry

PageAuthorsTitleNo.

60

2Norma Villanueva, Isvette Cruz, MarioOrtega and Carmen A. Vega

MEDIATING EFFECT OF ALIZARIN YELLOW INMICROBIAL FUEL CELLS WITH E. COLIB15

2Lissette Sepúlveda, Lilen Uchima andZarixia Zavala-Ruiz

BIOCHEMICAL CHARACTERIZATION OF THELAG-3 PROTEIN, A NEGATIVE REGULATOROF THE T-CELL IMMUNE RESPONSE

B14

1Eric R. Schreiter, María M. RodríguezGuilbe, William R. Montfort and JosephBonaventura

S-NITROSYLATION INDUCEDCONFORMATIONAL CHANGE IN BLACKFINTUNA MYOGLOBIN

B13

2Zuleika Sanoguet-Carrero, ChristinaSeda, Muriel Campbell and BelindaPastrana-Ríos

CHARACTERIZATION OF CENTRIN; ANMTOC’S PROTEINB12

1Zuleika Sanoguet, Héctor Mártir, JoelDíaz, Cristina Luiggi and BelindaPastrana-Ríos

PROTEIN EXPRESION AND ISOLATION OFRECOMBINANT HUMAN SFI1DOMAINS 1 AND 2

B11

2Ruth A. Quintana, Heidy J. Ríos, PedroJ. Báez, Mario Ortega and Carmen A.Vega

CYCLIC VOLTAMMETRIC STUDIES FOR THEHYDROGEN SULFIDE DETECTION USINGMODIFIED ELECTRODES WITH HEMOGLOBINI FILMS

B10

2Verónica Pérez-Romero and Elsie I.Parés-Matos

MOLECULAR BIOLOGY STUDIES ON YEASTFAP-1 PROTEINB9

1Raquel Nuñez, Lalisse Guillén, ZuleikaSanoguet, and Belinda Pastrana-Ríos

LARGE SCALE EXPRESSION ANDPURIFICATION OF RECOMBINANT CCENCAND ISOTOPE EDITED HCEN1

B8

2Daniel Narváez, Ibon Iloro, MelissaSerrano, Kathryn M. Ferguson,Elsa Cora and Belinda Pastrana-Ríos

H/D EXCHANGE OF sEGFR AND 13C-LABELEDEGF EXPRESSION AND ISOLATIONB7

1Daniel Narváez, Nancy Guillén, CarlosM. Camacho, Ibon Iloro, Lalisse Guillén,Elsa Cora and Belinda Pastrana-Ríos

TRANSFORMING GROWTH FACTOR-a ANDEPIDERMAL GROWTH FACTORB6

2Gina M. Monroy-Rojas, Miguel Monroig,Edna Negrón, Manuel Rodríguez andMaritza De Jesús-Echevarría

CHARACTERIZATION OF GROUND COFFEEAROMA FROM PUERTO RICO USING THESOLID PHASE MICROEXTRACTIONTECHNIQUE (SPME) AND GASCHROMATOGRAPHY COUPLED TO MASSSPECTROMETRY(GC/MS)

B5

1Cristina López Fagundo, Frances ValesLara, Elisa C. Alfaro Malavé, Eric R.Schreiter, and Belinda Pastrana-Ríos

EXPRESSION AND ISOLATION OF HUMANCENTRIN I (HCEN I)FOR ITS CRYSTALLIZATION

B4

2Ana María Gómez, Nidia Muñoz,Jessica Ríos and Belinda Pastrana-Ríos

CLONING OF HUMAN SFI1 CENTRIN-BINDINGDOMAINS AND MUTANTS OF CENTRIN INTOPROTEIN EXPRESSION VECTORS

B3

1Carmelo García, Luis E. Piñero andDionne Hernández

PHOTODESTRUCTION OF 2-CHLORINATEDPHENOTHIAZINESB2

2Joel Díaz, Zuleika Sanoguet, Ana MaríaGómez, and Belinda Pastrana

EXPRESSION, ISOLATION AND PURIFICATIONOF HCEN 1 VARIANTSB1

Track B: Biochemistry

61

1

Alvaro J. Peña-Quevedo, Robert B.Cody, Nelmary Rodríguez, DeborahNieves, Miguel Castro-Rosario, NairmenMina-Camide,and Samuel P.Hernández-Rivera

CHARACTERIZATION AND DIFFERENTIATIONOF HIGH ENERGY AMINE PEROXIDES BYDART-TOF-MS AND VIBRATIONALMICROSCOPY

C13

2Sandra Peña, Edwin de la Cruz, SamuelP. Hernández-Rivera

DEVELOPMENT OF SPME-HPLCMETHODOLOGY FOR DETECTION OFNITROEXPLOSIVES

C12

1Leonardo Pacheco-Londoño, Oliva M.Primera-Pedrozo and Samuel P.Hernández-Rivera

DETECTION OF EXPLOSIVES BY STANDOFFINFRARED AT LABORATORY SCALEC11

2

Deborah Nieves, Oliva M. Primera-Pedrozo,Leonardo Pacheco-Londoño andSamuel P. Hernandez-Rivera

DETECTION OF CHEMICAL WARFAREAGENTS SIMULANTS (CWAS) USING FIBEROPTIC COUPLED GRAZING ANGLE PROBE-FTIR

C10

1

Tatiana Luna-Pineda , Kristina Soto-Feliciano, Edwin De La Cruz-Montoya,Carlos Ríos-Velázquez and Samuel P.Hernández-Rivera

NORMAL RAMAN AND SURFACE ENHANCEDRAMAN SPECTROSCOPY DETECTION OFBIOLOGICAL AGENTS

C9

2Jackeline I. Jerez Rozo, Ana MariaChamoun, Joany Hernández andSamuel P. Hernández-Rivera

DETECTION OF NITRO-EXPLOSIVES BYENHANCED RAMAN SCATTERING ONNANOPARTICLE SUBSTRATES: Ag AND AuCOLLOIDS AND Au-Ag ALLOY

C8

1Madeline S. León-Velázquez, RobertoIrizarry and Miguel E. Castro

THE ELECTRON CONDUCTION IN COLLOIDALSYSTEM: A KINETIC STUDY OF AG2SSEMICONDUCTOR NANOPARTICLEFORMATION

C7

2Jackeline I. Jerez Rozo, Ana MariaChamoun, Joany Hernández andSamuel P. Hernández-Rivera

DETECTION OF NITRO-EXPLOSIVES BYENHANCED RAMAN SCATTERING ONNANOPARTICLE SUBSTRATES: Ag AND AuCOLLOIDS AND Au-Ag ALLOY

C6

2Ricardo Infante-Castillo, and Samuel P.Hernández-Rivera

THEORETICAL AND EXPERIMENTALVIBRATIONAL AND NMR STUDIES OF RDXC5

1

Gloria Marcela Herrera-Sandoval, LuzMarina Ballesteros , Nairmen Mina , JulioBriano and Samuel P. Hernández-Rivera

FTIR AND RAMAN SIGNATURES OF TNT-MONTMORILLONITE CLAY PARTICLESC4

2Miguel A. González Santiago, SamuelHernandez and Miguel E. CastroX-RAY PHOTOELECTRON STUDY OF RDXC3

1Raquel Feliciano and Miguel CastroQUANTUM DOT SENSING: THE EFFECT OFNO2 CONTAINING ORGANICS ON CdSBLINKING RATE

C2

2

Bibiana Báez, Vivian Florián, Samuel P.Hernández-Rivera, Andrea Cabanzo,Sandra Correa, Maik Irrazabal, Julio G.Briano, Miguel E. Castro

DETECTION OF CHEMICAL SIGNATURESFROM TNT BURIED IN SAND AT VARIOUSAMBIENT CONDITIONS

C1

Track C: Materials Chemistry

62

1Emlyn Vélez, Damian Reyes andCarmen A. Vega

DISSOCIATION CONSTANTS OF ACETIC ACIDIN 15 AND 35 W/W % ISOPROPANOL-WATERSOLVENT FROM 5 TO 35 OC AT TEN DEGREESINTERVALS

C20

2

Yadira Soto –Feliciano, Oliva M.Primera-Pedrozo, Leonardo Pacheco-Londoño andSamuel P. Hernandez-Rivera

TEMPERATURE DEPENDENCE OF THE LIMITSOF DETECTION OF TNT ON METALLICSURFACES USING FIBER OPTIC COUPLED-FTIR

C19

1Priscila Santiago, Miguel Santiago andMiguel Castro

SCANNING TUNNELING ELECTRONMICROSCOPY STUDIES OF RuNANOSTRUCTURES

C18

2

Nelmarie Rodríguez –Cardona, Oliva M.Primera-Pedrozo, Leonardo Pacheco-Londoño and Samuel P. Hernandez-Rivera

FIBER OPTIC COUPLED GRAZING ANGLEPROBE-FTIR DETECTION OF 2,4,6-TRINITROTOLUENE ON SURFACES

C17

1Rosángela Rivera, Miguel A. Muñoz,and Nairmen Mina

ADSORPTION COEFFICIENTS FOR TNT-SOILAND TNT-CLAY INTERACTIONSC16

2Carlos Peroza, Marissa Morales, LeoPacheco, Raquel Feliciano, SamuelHernandez and Miguel Castro-Rosario

TOWARD REAL TIME MONITORING OF NON-FRIENDLY CHEMICALS IN THEENVIRONMENT: A NIR STUDY OF NITROORGANICS

C15

1Gabriel Perez, Edwin De La Cruz, VictorDe La Cruz, Leonardo C. Pacheco andSamuel P. Hernández-Rivera

PHOTODEGRADATION KINETICS OFEXPLOSIVES WITH TiO2 NANOPARTICLESC14

63

AFICHES DEAFICHES DEINVESTIGACIÓNINVESTIGACIÓN

A1TOTAL SUSPENDED PARTICULATE AT THE UNIVERSITY OF PUERTO RICO

MAYAGÜEZ CAMPUS CHEMISTRY DEPARTMENTAnita Crespo Vázquez, 1 Víctor Fernández-Alos, 1 José R. Rivera-Negrón1, 2 and

Maritza De Jesús Echevarría 11Department of Chemistry, University of Puerto Rico, Mayagüez, PR

2Department of Chemical Engineering, University of Puerto Rico, Mayagüez, PR

Total suspended particulate matter, TSP, refers to all liquid and solid particles inthe atmosphere. The first scale to classify the amount of particulate in the air wasregulated by Clean Air Act 1987; Environmental Protection Agency (E.P.A.)improves the scale or size by using the particulate aero diameter related toconcentration measurements by gravimetric analysis. The Particulate Matter (PM10)aerodynamics diameter of 10 µm (µm = 10-6 meters) PM10, that includes individualparticles with aerodynamic diameter from 3.0 µm to 10 µm, (e.g. the averagediameter human hair is 70 µm). PM10 or coarse particulate, are emitted by fossil-fuel, incomplete combustion, and by mechanical process, such as forestal fires,volcanoes and dust storms. Additional factors are the transformation of the particlesalready suspended in the atmosphere that could happen by interaction of the UV-light, photochemical reactions and by hydroscopic's particulate which absorbhumidity. The identity of these compounds may provide clues to the origin.TSP/PM10 may contain considerable quantities of inorganic compounds or heavymetals with carcinogenic properties such as selenium, mercury, lead, cadmium,chromium and zinc. The 24-hour objective was to measure and analyze theTSP/PM10 before, during and after any atmospheric activities. The preliminary datademonstrated that during the dry season, the highest average TSP/PM10 was inMarch 2005. We found direct correlation between the maximum value of TSP andthe highest incident of biomass fires in the area of Mayagüez during March and Aprilmonth.

64

A3CHEMISTRY EXPERIENCES IN ENVIRONMENTAL ENGINEERING PROJECTS THROUGH THE

CLASS INCI 4998: UNDERGRADUATE RESEARCHMaría Irizarry Montalvo1, Ricardo Báez Vázquez1, Luis Benítez Alicea1, Daniel Concepción James2, Ingrid

Padilla1, and Sangchul Hwang1(*)

1Department of Civil Engineering, University of Puerto Rico, Mayagüez, PR 006812Department of Mechanical Engineering, University of Puerto Rico, Mayagüez, PR 00681

Knowledge of chemistry and biology is vital to environmental engineering students. Currently, theDepartment of Civil Engineering (INCI) at the University of Puerto Rico at Mayagüez has a Master and aPh.D. program in the area of Environmental Engineering. Undergraduate Students can also acquire anEnvironmental Certificate when they complete the coursework required. The Class INCI4998:Undergraduate Research is an example class where undergraduate students are involved in variousenvironmental engineering projects which demand important multidisciplinary concepts and knowledge,especially in chemistry. In this presentation, we will show our hands-on chemistry experience inEnvironmental Engineering Projects through the INCI 4998 class. A physiochemical sorption study is in progress to quantify macro sorption of explosives-relatedcompounds (ERCs) onto tropical sandy and clayey soils under different temperatures and different visiblelight levels to account this mechanism for retardation in the ERCs fate and transport. This research isimportant in that it provides an insight into limitation of the ERCs transport due to sorption to the soilmatrices under the different environmental factors. A dissolution kinetic study is being conducted todetermine the dissolution flux of the ERCs. This advective and diffusive chemical phenomenon is ofessence to understand the movement of ERCs with infiltrating water in soils. Currently, focus is given to theeffect of infiltration amount on the ERCs dissolution flux. Very few studies have been conducted to evaluatethe effect of flow reversal on the fate and transport of ERCs through variable-saturated porous media. Anadvection column is being used to characterize advective (fluid flow), dispersive, mass transfer and reactivetransport and evaluate their relative importance in function of the environmental conditions imposed,including temperature, soil type, water content, and fluid flux. The field-scale lysimeters constructed in thefront yard of the INCI are to be instrumented with sensors to monitor transport of water, gas and ERC atdifferent spatial and temporal scales under variable environmental and boundary conditions in the soil. Mostof the environmental conditions (wind, light, temperature, relative humidity, evaporation) are variable anduncontrolled, but they are monitored while monitoring spatial and temporal concentrations of the ERCs.*Corresponding author phone and e-mail: 787-832-4040 x.3454, shwang@uprm.edu

A2NANOSTRUCTURED SILVER-POLYMER SUBSTRATES FOR THE SURFACE ENHANCED RAMAN

SCATTERING (SERS) DETECTIONOF TRACE AROMATIC COMPOUNDSM. A. De Jesús 1(*), J. O. Oran 2, N. Abu-Hatab 2, and M. J. Sepaniak 2

1University of Puerto Rico, Mayagüez; P.O. Box 9019, Mayagüez PR 006812University of Tennessee, Knoxvile; 552 Buehler Hall, Knoxville TN 37996

The release of aromatic pollutants such as nitroaromatics, naphthalene derivatives, endocrinedisrupter’s, and certain organic dyes in natural waters constitutes a matter of public health. Therefore thereis interest for the use of information-rich methods for the detection of these substances and theirdecomposition products in aqueous media. The portability, large amount of available structural informationand the tremendous enhancement of the Raman signal, makes of SERS an attractive technique for thedetection of trace organic contaminants in aqueous media. Despite these advantages, SERS has not beenestablished as a routine analytical tool owing to limitations in substrate reproducibility and linear range. Akey element to improve the analytical capabilities of SERS resides in the performance characteristics ofsubstrate. Variables such as shape, size, and homogeneous distribution of the metal nanoparticlesthroughout the surface are important in the design of more analytically sensitive and reliable substrates.This work reports the use of metalized MA 2403N nanostructures for the detection of aromatic compoundsin aqueous media. This novel approach considerably improves the reproducibility and the sensitivity of thetechnique under normal Raman mapping conditions. The results show a useful range of two orders ofmagnitude with detection limits as low as 3×10-8 M and a precision of <30% RSD over the mapped surface.The influences of different experimental variables such as chemical nature, nanostructure morphology, andpH on the potential use of the technique for the detection of environmental pollutants are presented. *Corresponding author e-mail: mdejesus@uprm.edu

65

A5THE RAINWATER QUALITY ON THE UNIVERSITY OF PUERTO RICO AT MAYAGÜEZ

CAMPUSMarianne Pérez-Bosch, 1 Cynthia Caraballo Alvarez, 2 Ana M. Rivera-López 2, Belitza A. Brocco-

Jaime1 and Maritza De Jesús Echevarría1

1Department of Chemistry, University of Puerto Rico, Mayagüez, PR2Department of Chemical Engineering, University of Puerto Rico, Mayagüez, PR

Rainwater collection systems were widely used before well drilling equipment and treatedmunicipal water supplies became available. In many parts of the world, rainwater still providesthe majority of the water needed to meet agricultural requirements and, in some cases, potablewater as well. Considering that all surface water in PR could possibly be polluted by both organicand inorganic contaminants and, since a systematic study of rain events throughout the differentprecipitation areas of the island has not been undertaken, a special project has been takingplace in the Chemistry Department of the University of Puerto Rico, Mayagüez Campus sinceAugust of 2004. The objective of this research was to increase knowledge about the quality ofthe rainwater in the city of Mayagüez. The project will be first to pick three sampling sites on theroof of the Chemistry Building located 60 feet high of the UPR-Mayagüez-Campus. Therainwater is going to be collected through a system that consists of two liter bottles ofpolyethylene connected to a plastic funnel and overflow tube on top for one week. Once weekly,the bottles samples collected are carried to the laboratory. To prevent change in composition thesamples have to be processed immediately to prevent changes in ionic composition or thesamples must be stored at 4°C. Second, several chemical analyses are run on the rainwatersamples: the determination of the pH, the specific conductivity, the total dissolved solid (TDS),the salinity and ion concentration of nitrate (NO3

-), sulfate (SO4-2), chloride (Cl-) and the turbidity.

These results were compared with the data obtained during August to December of 2004.

A4STUDY OF THE ADSORPTION BEHAVIOR OF TETRACYCLINE ONTO CRUMB RUBBER

AND CARBON BLACK IN AQUEOUS SOLUTION BY LC/MS/MSSorelis Nieto Zambrano1, Félix Román1, Aidalú Joubert1 and Oscar Perales Pérez2

1Department of Chemistry, University of Puerto Rico, Mayagüez, PR2Department of General Engineering, University of Puerto Rico, Mayagüez, PR

The use of tire crumb rubber and carbon black was studied as adsorbents for the antibiotictetracycline (TC) from aqueous solutions by LC/MS/MS. The disposal of rubber tires represents amajor environmental hazard worldwide. Ironically, the same physically and chemically desirableproperties in rubber tires make their disposal and reprocessing very difficult. In Puerto Ricoalone, 4 million rubber tires are discarded annually and of that number less than 7% is recycled.TC is part of a new class of pharmaceutical environmental contaminant, with concentrationsthat range between nanograms to micrograms per liter. The detrimental effect of TC in the qualityof soils and water are a major concern due to development of microbial resistance to thesecompounds. Recent research showed that antibiotics could accumulate even after repeatedfertilization of the soil. Liquid chromatography / mass spectrometry offer great advantages in thedetermination of antibiotics due to their low volatility and thermal stability. The results of thisstudy showed that 48.22% and 59.80% removal of TC by adsorption onto tire crumb rubber ofmesh 14-20 and 30 respectively were obtained. TC was completely removed from aqueoussolution placed in contact for 24 hours with carbon black.

66

A7SO2 LOSS RATES IN THE PLUME EMITTED BY SOUFRIÈRE HILLS VOLCANO, MONTSERRAT

Lizzette A. Rodríguez1,2, I. Matthew Watson1, 3, Marie Edmonds4, Graham Ryan5, Vicky Hards5, 6, CliveM.M. Oppenheimer7, and Gregg J.S. Bluth1

1Geological and Mining Engineering & Sciences, Michigan Technological University, Houghton, Michigan,USA, 2Department of Geology, University of Puerto Rico, Mayagüez, PR., 3Earth Sciences, University of

Bristol, Queen’s Road, Bristol BS8 1RJ, UK, 4School of Environmental Sciences, University of East Anglia,Norwich NR4 7TJ, UK, 5Montserrat Volcano Observatory, Flemmings, Montserrat, BWI

6British Geological Survey, Keyworth, Nottingham NG12 5GG, UK, 7Department of Geography, DowningPlace, Cambridge University, Cambridge CB2 3EN, UK

In order to improve volcanological interpretation of SO2 flux data, it is necessary to quantify andunderstand SO2 loss rates in volcanic plumes as a function of meteorological environment and plume age.SO2 is lost in volcanic plumes through a number of mechanisms, including oxidation (conversion to sulfateaerosol), dry and wet deposition, absorption, and dissolution. Here we report SO2 measurements madewith two miniature ultraviolet spectrometers at Soufrière Hills volcano, Montserrat; a low altitude volcanowhose plume entrains humid marine air in the planetary boundary layer. Traverses beneath the ash-freeplume were made at various distances from the source (from ~2 km to ~16 km), thereby spanning plumeages of about 6 to 35 minutes. We find average SO2 loss rates in the order of ~10-4 s-1 (e-folding time of~2.78 hours), slightly lower than calculated previously for Soufrière Hills, indicating a longer lifetime of SO2.These are, however, in the high end of the range of loss rates measured at volcanoes (10-3 – 10-7 s-1),indicating short SO2 lifetimes. This work produces more accurate SO2 loss rates than previous work, andrepresents the general case in Montserrat. SO2 flux measurements made downwind from Soufrière Hillsvolcano significantly underestimate at-source SO2 emission rates, in the order of 70-140%, when notaccounting for the decay rate. Similar SO2 loss is likely to occur in plumes from other low altitude volcanoesunder conditions of high relative humidity (~20% of active volcanoes worldwide). These results suggest thatthe global volcanic SO2 emission rate may be underestimated as the estimates are based onmeasurements taken downwind of volcanoes, by which time significant loss of SO2 may have taken place.The loss rates calculated here could be used, in conjunction with downwind SO2 fluxes, to estimate at-source SO2 emission rates from volcanoes.

A6TRAFFIC DENSITY AND THE CORRELATION WITH THE DETERMINATION OF TOTAL SUSPENDED

PARTICLES USING A HIGH VOLUMEJosé R Rivera Negrón 1, 2 and Maritza De Jesús Echevarría1

1Department of Chemistry, University of Puerto Rico, Mayagüez, PR2Department of Chemical Engineering, University of Puerto Rico, Mayagüez, PR

Driving a car can be considered the most “polluting” daily activity. Vehicles can impact the environmentin many ways, beginning when a car is manufactured. However, much of the environmental harm takesplace during driving and is drastically related with fuel consumption. Most of the ecological harmful effectsassociated with motor vehicles happen when they are used, due to pollution in their exhaust and pollutionlinked with supplying the fuel. When fossil fuels are burned up in car engines, combustion is never perfectand, as a result, a mix of hazardous pollutants comes out of the tailpipe such as NOx, SO2 and HCemissions. In an attempt to increase understanding about the correlation of total suspended particles,TSP/PM10 and the traffic density in the entrance road of the University of Puerto Rico-Mayagüez Campus,UPR-Mayagüez a research has begun in the Chemistry Department. A roadside measurement is used witha high volume sampler, HVS. After analyzing many factors, Wednesday was selected to be the test day.The filter is exposed for 24 hours in the HVS. Then, we determined the TSP/PM10 by a gravimetric method.Results for the first four months of the research, August to November, were calculated. The arithmetic meanwas 53.49 µg/m3 and the higher TSP/PM10 value was 95.38 µg/m3. According to the EnvironmentalProtection Agency, EPA, the arithmetic mean for TSP/PM10 could be not more than 50 µg/m3 and 150µg/m3 during a 24 hour period. Although the determined TSP/PM10 values do not exceed the EPA standardvalue for a 24 hour period the mean value is above the standard by 3.49 µg/m3.These results lead us tocontinue our research goals. We are going to start the extraction of the filter material and we plan toanalyze heavy metals using atomic absorption spectroscopy with an emphasis on lead.

67

B1EXPRESSION, ISOLATION AND PURIFICATION OF HCEN 1 VARIANTSJoel Díaz, Zuleika Sanoguet, Ana María Gómez and Belinda Pastrana-Ríos

Department of Chemistry, Center for Protein Structure, Function and Dynamics,University of Puerto Rico, Mayagüez Campus

Centrin is an acidic protein with a molecular weight of ~ 20 kDa. This proteinbelongs to the EF-hand superfamily of calcium binding proteins. Centrin was firststudied in flagellated organisms, such as Chlamydomonas reinhardtti and later wasfound as a component of centrosome and mitotic spindle in higher eukaryotics. InHomo sapiens three genes that encode for human centrin (hcen) have been identifiedlocated on chromosomes 5, 18 and X and were designated as Hcen3, Hcen1, andHcen2, respectively. Human centrin 1 has been localized at the base of the flagellarapparatus in sperm cells and its function is associated with sperm motility. Large scale expression was performed using a 5L fermentor. The expression ofthe recombinant variants of Hcen1 (F5W, F162W, F162W/Y172W), was carried-outusing Escherichia coli BL 21lDE3 cells with IPTG induction. Hcen 1 variants werecharacterized by Agilent microfluidics, UV and sent for sequencing and MS analysisto validate the incorporation of the mutation at the desired location and to assesspurity. Also, these tryptophan containing variants have a characteristic aromaticabsorbance which was detected by UV and compared with the Hcen 1 wild typespectrum. Future fluorescence and sedimentation analyses of Hcen 1 variants are tobe done.Project Supported by: NIH-MBRS-SCORE Program [SO6GM08103]

A8LIQUID CHROMATOGRAPHY MASS SPECTROMETRY LABORATORY TO

ENHANCE EDUCATION IN FOOD, SOILS AND ENVIRONMENTAL SCIENCESFélix Román and Aidalú Joubert

Department of Chemistry, University of Puerto Rico, Mayagüez, PR The acquisition of a state of the art LC/MS/MS instrument to be used in FoodChemistry, Soil Chemistry and Environmental Chemistry by the ChemistryDepartment at UPR-Mayagüez will enhance students and faculty development andwill promote higher education in Food and Agricultural Sciences. The majorobjectives of this work are: 1) to provide faculty and students accesses to a state-of-the-art LC/MS/MS facility enabling students training, collaboration and service tolocal industry, especially in the agriculture and food sector, 2) to build the necessaryinstrumentation infrastucture to support future Ph.D. programs in Agronomy and Soiland in Applied Chemistry, 3) to increase research productivity of faculty and provideopportunities for collaboration in projects with the industrial sector of the island, 4) toattract high quality minority students to participate in the undergraduate and graduateprograms of Food Science, Agronomy and Soils and Chemistry capable of enhancingthe Puerto Rico and Nation’s food and agriculture scientific and professionalworkforce. This poster will present the special features of the LC/MS/MSinstrumentation as well as the progress of the project.

68

B3CLONING OF HUMAN SFI1 CENTRIN-BINDING DOMAINS AND MUTANTS OF CENTRIN

INTO PROTEIN EXPRESSION VECTORSAna María Gómez, Nidia Muñoz, Jessica Ríos and Belinda Pastrana-Ríos

Department of Chemistry, University of Puerto Rico, Mayagüez, PR The centrosomal protein hSfi1 contains 23 repetitive domains that bind centrin. Bothproteins are constituents of contractile fibers in the centrosome and play essential roles incentriole duplication and separation. The long term goal of this research is to reveal themolecular interactions between centrin and hSfi1 by analyzing individual hSfi1 domains as wellas complexes with mutants of human centrin 1 and 2. hSfi1 ORF (open reading frame) andseveral individual domains were amplified by pcr and subcloned into expression vectors thatallow the production of recombinant fusion proteins containing either a His tag (pET100) or aGST (Glutathione S-Transferase) tag (pGEX). Single hSfi1 domains 1, 2, 3, 10, 11, 12, double(1,2) and triple (1-3), (10-12) domains were successfully subcloned and confirmed bysequencing. On the other hand, in order to analyze the significance of a putative salt bridge inthe complex centrin-hSfi1 among aa105 in centrin and a basic aa (K,R orH) localized in thecentral region of hSfi1 domain, human centrin 1 and 2 genes were mutated at position E105Kusing the Quikchange site directed mutagenesis Kit (Strategene). All mutants were sequenced.This cloning work will produce the gene fusions necessary for a simplified purification of thehSfi1domains and the generation of centrin mutants essential in the understanding of thestructure, stability and dynamics of the hSfi1-centrin complex.Project Supported by: NIH-MBRS-SCORE Program SO6GM08103

B2PHOTODESTRUCTION OF 2-CHLORINATED PHENOTHIAZINES

Carmelo García, Luis E. Piñero and Dionne HernándezUniversity of Puerto Rico at Humacao, Humacao PR

The mechanism that induces the phototoxic response of 2-chlorophenothiazine derivativesis still unknown. The short-lived intermediates (cation radical, solvated electron, excited tripletstate and neutral radicals), the photoproducts and some metabolites have been postulated tobe responsible for this side-effect. To better understand the relationship between the molecularstructure of phenothiazines and their phototoxic activity, we studied in this work thephotophysics and photochemistry of 2-chlorophenothiazine derivatives in several solvents,determined their photodestruction quantum yields under anaerobic conditions usingmonochromatic light (313 nm) and performed theoretical calculations to explain ourexperimental results. Using absorption- and emission-spectroscopy, 1H- and 13C-NMR, GC-MS, and steady-statephotolysis, we demonstrated that the photochemistry of 2-chlorophenothiazine derivativesunder aerobic conditions in organic solvents do not induce the drug photodegradation. This infact implies that whatever amount of singlet oxygen is produced, it does not react with the drugground state. Nevertheless, photodegradation is observed in air saturated aqueous solutions,indicating that the photochemistry of 2-chlorophenothiazine derivatives in water is very different.The photochemistry of these compounds in organic polar solvents (such as methanol andacetonitrile) under anaerobic conditions induces photodegradation, but not if the solvent is non-polar. Therefore, we postulate a “triplet state-polar solvent” complex, which is responsible forthe neutral radical formation and consecutive phototoxic side-effect. This complex mustinclude, at least, one drug intermediate and one membrane component.

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B5CHARACTERIZATION OF GROUND COFFEE AROMA FROM PUERTO RICO USING THE SOLID

PHASE MICROEXTRACTION TECHNIQUE (SPME) AND GAS CHROMATOGRAPHY COUPLED TOMASS SPECTROMETRY(GC/MS)

Gina M. Monroy-Rojas 1, Miguel Monroig 3, Edna Negrón,4 Manuel Rodríguez,5 andMaritza De Jesús-Echevarría2

1Food Science and Technology Program, University of Puerto Rico, Mayagüez, PR`, 2Department ofChemistry, University of Puerto Rico, Mayagüez, PR, 3College of Agriculture, University of Puerto

Rico, Mayagüez, PR, 4Food Science and Technology Program, University of Puerto Rico-Mayagüez,5Chemistry Professor (retired)

The main objective of this research was the identification and semiquantitative determination of thevolatile compounds responsible for the aroma of the two principal coffee species and their respectivevarieties grown at three different altitudes in Puerto Rico: Coffea Arabica L. (Borbón, Caturra andLimaní) and Coffea canephora (Robusta). The techniques of Solid Phase Microextration (SPME)coupled to Gas Chromatography and Mass Spectrometry (GC/MS) were utilized in the analyses. The identified compounds found responsible for the aroma of coffee can be grouped in classes likespyrazines, furanes, ketones, aldehydes, pyrroles, alcohols, thiophenes and others. The furanes and thepyrazines were the major compounds found in the two species and their respective varieties. Thecoffee arábigo presented greater quantities of furanes while in the fisiRobusta coffee the pyrazineswere predominant. A chromatographic digital impressions was found, which was characteristic of eachvariety within the studied species.

B4EXPRESSION AND ISOLATION OF HUMAN CENTRIN I (HCEN I)

FOR ITS CRYSTALLIZATIONCristina López Fagundo2, Frances Vales Lara2, Elisa C. Alfaro Malavé2, Eric R. Schreiter1,2, and

Belinda Pastrana-Ríos1,2

1 Centrer for Protein Structure Function and Dynamics2Department of Chemistry, University of Puerto Rico, Mayagüez, PR 00681

Centrin is a 20kDa protein, member of the EF-hand calcium binding superfamily. It is localized at themicrotubule organizing center of eukaryotic organisms. Like other members of the EF-hand family,centrin interacts with and modulates the function of other proteins in a calcium-dependent manner. Inhumans, centrin is essential for centrosome duplication during mitosis. Human centrin 1 has beenlocalized at the base of the flagellar apparatus in sperm cells and its function is associated with spermmotility. To understand how it interacts with its protein targets, its crystal structure will be determined. Inorder to accomplish this, large quantities of pure recombinant protein are required; therefore,expression and purification of the protein are needed to determine the structural changes that occurduring binding to the target peptide. Large scale expression was performed using a 5L fermentor. Theexpression of Hcen1 was carried-out using Escherichia coli BL 21lDE3 cells with IPTG induction.Isolation and purification of the protein was performed using a phenyl sepharose chromatographycolumn and an anion exchange (HQ) chromatography column, respectively. Agilent microfluidics wasused to characterize Hcen1. Future sequencing and MS analysis will be performed to assess purity.We will now attempt to crystallize human centrin I in complex with a peptide from one of its cellularbinding partners, Sfi1. Recently the Saccharomyces cerevisiae centrin, Cdc31p, was crystallized incomplex with two different multi-repeat containing peptides from the Sfi1p protein (Li et al., J. Cell. Biol.173:867-877, 2006). One complex was crystallized using 0.2M sodium acetate, 18% polyethyleneglycol 3350; the other was crystallized using 9% isopropanol, 0.1M MES, pH 6.2 and 0.2M calciumacetate. We will attempt crystallization under these conditions as well as sparse-matrix screening.*Corresponding authors e-mails: alfaro.elisa@gmail.com, clopezfagundo@yahoo.com,vales.frances@gmail.com, eric_sch@mit.edu, belinda@uprm.edu

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B7H/D EXCHANGE OF sEGFR AND 13C-LABELED EGF EXPRESSION AND ISOLATION

Daniel Narváez1, Ibon Iloro1, Melissa Serrano3, Kathryn M. Ferguson2,Elsa Cora3,4 and Belinda Pastrana-Ríos1,4

1Department of Chemistry, University of Puerto Rico, Mayagüez, PR2Department of Physiology, University of Pennsylvania School of Medicine, Philadelphia, PA

3Department of Biochemistry, University of Puerto Rico, Medical Sciences Campus PO Box 365067 SanJuan, Puerto Rico 00936-5067, 4Center for Research in Protein Structure, Function and Dynamics,

University of Puerto Rico, Mayagüez, PR

Epidermal Growth Factor Receptor (EGFR) is a transmembrane glycoprotein found primarily on cellsof epithelial origin. It is a member of a family of growth factors receptors with tyrosine kinase activity.Binding of ligands to the growth factor receptor triggers a number of cellular responses that eventuallylead to cell proliferation. Recent crystallographic studies, have determined several structures for sEGFR-ligand complex under varying conditions. Ligand induced receptor dimerization was determined to be a(2:2) ratio and hydrogen bonding being a common interaction. H/D exchange studies of sEGFR usingAttenuated Total Reflectance (ATR) FT-IR spectroscopy have provided the dynamics of exchange at theside chain and backbone levels. The spectra obtained were studied by a two-dimensional correlationanalysis to determine order of events during the exchange process. Changes in intensity and bandposition characteristic of the H/D exchange process were observed in the spectral region of 1700 to1400 cm-1. Expression and isolation of 13C-labeled EGF was performed for a future comparative studybetween sEGFR and the sEGFR/13C-ligand complex. These studies will determine the differences inaccessibility to its aqueous environment, conformation and dynamic behavior upon H/D exchange.This work was supported by NIH NCRR COBRE Grant P20 RR16439-01.

B6TRANSFORMING GROWTH FACTOR-α AND EPIDERMAL GROWTH FACTOR

Daniel Narváez1, Nancy Guillén2, Carlos M. Camacho2, Ibon Iloro1, Lalisse Guillén2, Elsa Cora1,3 andBelinda Pastrana-Ríos1,2*

1Center for Protein Structure Function and Dynamics, 2Department of Chemistry, University of PuertoRico, Mayagüez Campus, PO Box 9019 Mayagüez, PR 00681-9019

3Department of Biochemistry, University of Puerto Rico, Medical Sciences Campus, PO Box 365067 SanJuan, Puerto Rico 00936-5067

Transforming growth factor-alpha (TGF-α) is a single chain growth factor containing 50 amino acids.TGF-α shares about 30% sequence identity with Epidermal Growth Factor (EGF) and competes as aligand with EGF for the same receptor site of Epidermal Growth Factor Receptor (EGFR). EGFR is atransmembrane glycoprotein found primarily on cells of epithelial origin. It is a member of a family ofgrowth factor receptors with tyrosine kinase activity. Binding of ligands to the growth factor receptortriggers a number of cellular responses that eventually lead to cell proliferation. The structure of theseligands has been determined. Although the dynamics and kinetics of H/D exchange has not beenelucidated. H/D exchange studies of the ligands were performed using Attenuated Total Reflectance(ATR) FT-IR spectroscopy. The spectra obtained were analyzed by a two-dimensional correlation todetermine which regions of the proteins go through the H/D exchange first and the subsequent order ofevents during the exchange process. Changes in intensity and band position characteristic of the H/Dexchange process were observed in the spectral region of 1700 to 1400 cm-1. The goal of this project isto provide information on the ligands’ accessibility to its aqueous environment, its conformation and itsdynamic behavior upon H/D exchange. These, results provide essential information towards theunderstanding of receptor regulation.Project Supported by NIH-COBRE Grant P20 RR16439-01 (B.P.R. and E.C.) and the University ofPuerto Rico.

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B9MOLECULAR BIOLOGY STUDIES ON YEAST FAP-1 PROTEIN

Verónica Pérez-Romero and Elsie I. Parés-Matos*Department of Chemistry, University of Puerto Rico, Mayagüez, PR

FKBP12 Associated Protein-1 (FAP-1) gene was obtained by amplification from freshlygrown Saccharomyces cerevisiae cells with the zymolase PCR method. Amplicons with alength of approximately 3K bp were cloned into plasmid Bluescript II SK, and subsequentlysubmitted to restriction digestion analysis and DNA sequencing. Characterization was alsoperformed with the freeware program pDRAW32 and the results obtained from the computeranalysis revealed restriction digestion patterns similar to our experimental results. For fap-1protein expression, the T7 gene on the recombinant plasmid was activated with isopropyl-beta-D-thiogalactopyranoside (IPTG). The fap-1 protein will be characterized by western blot,immunoblotting and matrix assisted laser desorption/ionization (MALDI) techniques. Todetermine the fap-1 function as a possible transcription factor, the Electrophoretic MobilityShift Assay (EMSA) method will be used with several oligonucleotides containing different X-box binding sequences for the detection and analysis of protein-DNA interactions. Some ofthe X-box elements used for this study are contained in 45 bp oligonucleotide sequencesobserved in three different and important yeast genes: (1) 5’-ATC CAG AAG TCT GCT ATCTGT CTC TGG GTA GAC ATT GAT-3’, (2) 5’-ATC CTG CAG CTG GCA ACT GTG ACG TCATCA CGA T-3’, and (3) 5’-ATC CTC TAA CTA GCA ACT GAT GAT GCT GGA T-3’.*Corresponding author e-mail: epares@uprm.edu

B8LARGE SCALE EXPRESSION AND PURIFICATION OF RECOMBINANT CCENC AND

ISOTOPE EDITED HCEN1Raquel Nuñez, Lalisse Guillén, Zuleika Sanoguet, and Belinda Pastrana-Ríos

Department of Chemistry, University of Puerto Rico, Mayagüez , PR

Centrin is a calcium-binding protein associated with microtubule organizing centers(MTOC’s). Chlamydomonas reinhartii centrin (Ccen) has been used as a model protein forhuman centrin homologues 1, 2 and 3. Hcen1 is located at the base of the flagella and isassociated with sperm motility. Current efforts are directed towards understanding thestructure-function relationship of this protein and its interaction with biologically relevant targetpeptides. We have previously characterized the effects of Ca2+ binding and phosphorylation(post-translational modification) by Fourier Transform Infrared (FT-IR) spectroscopy. Toaccomplish this goal large quantities of pure recombinant protein are required. Fermentorbased bacterial expression using 2xYT or 13C enriched minimal media have been carried-outto obtain sufficient quantities of the desired protein for subsequent isolation and purification.Pellet weight for Ccen-C was 71.03 g vs 23.76 g for the native isotope and edited HCen1.Details of fermentor based expression and optimization will be provided.

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B11PROTEIN EXPRESION AND ISOLATION OF RECOMBINANT HUMAN

`SFI1DOMAINS 1 AND 2Zuleika Sanoguet, Héctor Mártir, Joel Díaz, Cristina Luiggi, and Belinda Pastrana-Ríos*

Department of Chemistry, University of Puerto Rico, Mayagüez PR The human centrosomal protein, hSfi1, is localized to the centriole. This protein bindshuman centrin, a calcium binding EF-hand protein, through 23 centrin binding sitesthroughout its sequence. The centrin binding sites are comprised of 33 amino acids(X9A10X3LLX2W/FX6). The role of centrin-Sfi1 interactions in the dynamic structure of thecentriole is currently unknown. Recombinant hSfi1 will be overexpressed and purified forfuture centrin-Sfi1 complex studies. This construct transformed into BL21(DE3)RIL E. colicells was grown in a five liter fermentor and induced with IPTG at log phase, for itsexpression. Subsequent isolation of hSfi1 was accomplished using Ni-NTAchromatography followed by successful removal of the His-Tag with eterokinase protease.The isolated protein was then analyzed by microfluidics lab-chip electrophoresis, SDS-PAGE, and UV-Vis spectroscopy. Removal of the His-Tag was carried by using size-exclusion chromatography. The purified protein sample was sent for MS analysis andpartial amino acid sequencing at the Wistar Institute at the University of Pennsylvania. Thiswork will generate sufficient quantities of purified hSfi1 protein to be biophysicallycharacterized by differential scanning calorimetry (DSC) and FT-IR spectroscopy, essentialto understanding its structure and stability.*Corresponding author e-mail: belinda@hpcf.upr.edu Project Supported by: NIH-MBRS-SCORE Program SO6GM08103

B10CYCLIC VOLTAMMETRIC STUDIES FOR THE HYDROGEN SULFIDE DETECTION

USING MODIFIED ELECTRODES WITH HEMOGLOBIN I FILMSRuth A. Quintana, Heidy J. Ríos, Pedro J. Báez, Mario Ortega and Carmen A. Vega*

Department of Chemistry, University of Puerto Rico, Mayagüez, PR

Cyclic Voltammetric Studies of the reactivity of recombinant hemoglobin I (rHbI) fromLucina pectinata with hydrogen sulfide were performed. Glossy Carbon (GC), Platinum (Pt)and Gold (Au) electrodes were modified with a thin film of HbI. These films were formed byleaving until dryness inside a dessicator, 5 µL of rHbI (0.5 mM) on the electrode surfaces. Athree-electrode arrangement (work electrode or modified electrode, auxiliary platinumelectrode and constant potential Ag/AgCl electrode) was used. Voltammograms wereobtained at a rate of 100 mV/s and a sensitivity of 1 µA/V in a pH 6.3 buffer phosphatesolution as supporting electrolyte. Hydrogen sulfide was generated from a 48 mM sodiumsulfide solution. For every voltammogram 5.0 mL portions were added, using 10.00 mL ofbuffer as a blank solution. The modified gold electrode presented significant increments inthe oxidation half wave at (-702 ± 13)mV vs. Ag/AgCl when the hydrogen sulfide solutionswere added, while GC and Pt electrodes did not show significant changes in the oxidativewave. A good relationship between the H2S concentration added and the anodic intensity ofthe oxidation peak were observed when a plot of concentration of H2S vs the intensity ofthe oxidation peak at constant potential E = -702 mV was constructed.*Corresponding author e-mail: cvega@uprm.edu

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B13S-NITROSYLATION INDUCED CONFORMATIONAL CHANGE IN BLACKFIN TUNA

MYOGLOBINEric R. Schreiter1, Maria M. Rodríguez Guilbe1, William R. Montfort2, Joseph Bonaventura1

1University of Puerto Rico, COBRE Protein Research Center, PO Box 9019, Mayagüez, PR00681-9019, 2University of Arizona, Department of Biochemistry & Molecular Biophysics,

1041 E. Lowell Street, Tucson AZ 85721-0088

Nitric oxide has been recognized for some time as an important biological signal since itsdiscovery as the agent released by endothelial cells that was responsible for relaxation ofvascular smooth muscle. More recently, it was recognized that proteins can be S-nitrosylatedon reactive cysteine residues, and that this post-translational modification is important forinfluencing a wide variety of cellular events. Although many cellular protein targets of S-nitrosylation have now been identified, comparatively little is known about the moleculardetails of this chemical modification in the context of proteins and how it influences theirstructure and function. Blackfin tuna myoglobin was S-nitrosylated at a single cysteine residue (Cys10) by atrans-nitrosylation reaction with free S-nitrosocysteine. X-ray crystallography was then usedto determine atomic resolution structures of the myoglobin before and after S-nitrosylation ofCys10. Here we show that the myoglobin protein from blackfin tuna can be reversibly S-nitrosylated at Cys10. Comparison of structures of the protein before and after S-nitrosylationreveals a conformational change involving the shift of several secondary structural elements,which is specifically induced by “wedging” of the SNO group between a helix and loop. Upontreatment of myoglobin-SNO with the reducing agent dithionite, we demonstrate in solutionand in a single crystal that the modification at Cys10 is lost and that the NO released bindsquantitatively to the reduced heme iron. These results have implications for the alteration of protein structure and functionfollowing S-nitrosylation. The ability of this post-translational modification to modulate proteinstructure and function lends support to its description as an important reversible redox-basedcellular signaling event.This work was funded by NIH grant 5P20RR016439-05 to the COBRE Protein ResearchCenter at the University of Puerto Rico.

B12CHARACTERIZATION OF CENTRIN; AN MTOC’S PROTEIN

Zuleika Sanoguet-Carrero, Christina Seda, Muriel Campbell and Belinda Pastrana-RíosDepartment of Chemistry, University of Puerto Rico, Mayagüez, PR

Recombinant Chlamydomonas centrin was used as a model protein to understand theeffects of phosphorylation on protein conformation. The purified protein was phosphorylatedin vitro using protein kinase A (PKA). The extent of phosphorylation was determined byMatrix Assisted Laser Desorption Mass Spectrometry (MALDI-MS). The conformationalchanges and the hydrogen / deuterium (H/D) exchange dynamics at the molecular level werestudied using Fourier Transformed Infrared spectroscopy (FT-IR) and two-dimensionalcorrelation analysis. This protein was observed to have a thermal transition temperature(Tm) of 112°C with a pre-transition at 70 °C, using Differential Scanning Calorimetry (DSC).The FT-IR results suggest that changes in the backbone occur prior to any other changewhen thermally perturbed while for the H/D exchange loops were affected first. Discussionof the results is relevant in describing its biological function and for future studies with sfi 1, atarget protein, essential in cell division.

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B15MEDIATING EFFECT OF ALIZARIN YELLOW IN MICROBIAL FUEL CELLS

WITH E. COLINorma Villanueva, Isvette Cruz, Mario Ortega and Carmen A. Vega *Department of Chemistry, University of Puerto Rico, Mayagüez, PR

Potentiometric measurements were made with microbial fuel cells for theconversion of chemical energy to electrical energy through the catalytic action ofEscherichia coli, using Alizarin Yellow as a mediator. A good mediator should beeasily reduced and oxidized, and facilitate the transfer of electrons during therespiratory process of the bacteria without killing them. The setup of the cellconsisted of two chambers separated by a semi-permeable membrane with inletsand outlets for N2 gas to remove oxygen and maintain anaerobic conditions. Thebacteria present in a phosphate buffer at ph 7.00 were placed at the anodecompartment, while a solution 0.1 M K3Fe(CN)6 was kept in the cathodecompartment, and each compartment filled with 20 mL of the correspondentsolutions. Carbon cloth measuring 2 cm x 4 cm served as electrodes in bothcompartments and 10 or 20 µmol of glucose were added as fuel. Preliminarystudies showed that Alizarin Yellow can be a suitable mediator when the amountsadded from a saturated solution of the redox dye were less than 30µL. Differentamounts of fuel were also studied in order to determine the efficiency of thesystem.*Corresponding author e-mail: cvega@uprm.edu

B14BIOCHEMICAL CHARACTERIZATION OF THE LAG-3 PROTEIN, A NEGATIVE

REGULATOR OF THE T-CELL IMMUNE RESPONSELissette Sepúlveda1, Lilen Uchima1 and Zarixia Zavala-Ruiz2

1Program of Industrial Biotechnology, University of Puerto Rico, Mayagüez, PR 2Department of Chemistry, University of Puerto Rico, Mayagüez, PR

The long-term goal of this project is to characterize the interaction of theregulatory T-cell protein lymphocyte activation gene-3 (LAG-3 or CD223) with itsligand, class II MHC proteins. The LAG-3 protein is expressed in activated naturalkiller (NK) cells, as well as CD4+ and CD8+ T-cells. This protein plays animportant role in negatively regulating T-cell activation and proliferation. LAG-3 is aCD4-homolog that, like CD4, binds to class II MHC proteins. Experiments will beperformed to determine the affinity and life-time constants between LAG-3 andclass II MHC molecules using analytical ultracentrifugation, dynamic lightscattering, and surface plasmon resonance. Understanding the biochemicalcharacteristics of the LAG-3: MHC II complex will facilitate the identification of themechanism by which this protein regulates the T-cell activation. The preparation ofconstructs for expression of the protein in E. coli, isolating and purifying it from theinclusion bodies and an optimizing fermentation process to produce the protein inlarge quantities have been carried out. Constructs for expression of the protein inSchreider-2 cells (insect cells) are also being made.

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C2QUANTUM DOT SENSING: THE EFFECT OF NO2 CONTAINING ORGANICS ON

CdS BLINKING RATERaquel Feliciano and Miguel Castro

Chemical Imaging Center, Department of Chemistry,University of Puerto Rico, Mayagüez, PR

Quantum dots (QD) are nanoparticles that exhibit particle-size dependentfluorescence properties. Among these properties, there is one known as “blinking”which is proposed to result from difference in electron hole recombination kineticsamong the different QD that can exist in a given sample. Measurements of thenanoparticle blinking frequency is an active research area due to their potential rolein sensing. In this presentation, we report on ongoing research activities towardsunderstanding the effect of local chemical environment in QD blinking frequencyusing femtosecond laser spectroscopy and electron microscopies. Results on theeffect of TNT on the blinking rate of samples of CdS QD will be presented.

C1DETECTION OF CHEMICAL SIGNATURES FROM TNT BURIED IN SAND AT

VARIOUS AMBIENT CONDITIONSBibiana Báez, Vivian Florián, Samuel P. Hernández-Rivera*, Andrea Cabanzo,

Sandra Correa, Maik Irrazabal, Julio G. Briano, Miguel E. CastroChemical Imaging Center / Center for Sensors Development

Department of Chemistry, University of Puerto Rico, Mayagüez, PR For the detection of explosives and their degradation products, new analyticalmethods have been developed and existing methods have been improved byincreasing their sensitivity and selectivity. Some of the analytical methods availablefor detection of explosives and degradation products are gas chromatography (GC),mass spectrometry (MS), high performance liquid chromatography (HPLC), and gaschromatography (GC) with mass spectrometry (GC/MS). This work presents thedesign and elaboration of the experiments for the detection of the spectroscopicsignature of TNT buried in sand and its degradation products. These experimentsare being studied using a series of soil tanks with controlled environmentalconditions such as: temperature, soil moisture content, relative humidity andradiation (UV and Visible). The Gas Chromatography (GC-µECD) and solid-liquidextraction with acetonitrile were used for the analysis of explosives. The tankssampling was performed in three points of surface. The results have demonstratedthat TNT and 2,4-DNT are the main explosives that reach the surface of tanks. Alsothe temperature and water content play a most important role in the degradation anddiffusion of the TNT. Finally the tanks were dismounted and sampling carried out indeep with the objective to obtain a concentration profile. The results demonstratedthat the highest concentration was located at 5 cm from surface.*Corresponding author e-mail: olivaprimera@yahoo.es.

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C4FTIR AND RAMAN SIGNATURES OF TNT-MONTMORILLONITE CLAY PARTICLES

Gloria Marcela Herrera-Sandoval1,*, Luz Marina Ballesteros 1, Nairmen Mina 1, Julio Briano 2 and SamuelP. Hernández-Rivera 1

Center for Chemical Sensor Development for Explosives, University of Puerto Rico-Mayagüez,Department of Chemistry, Mayagüez, PR, 2Chemical Engineering Department, Mayagüez PR

2,4,6-Trinitrotoluene (TNT) has a number of specific properties that make it a nearly ideal explosive formilitary applications. It is relatively stable with respect to non desired detonation, easy to store and handleand has a high explosive power. A broad variety of landmines contain TNT as the main explosive charge.There are several methods currently used to detect buried landmines, both physically and chemically. Thegoal of this work is develop new methods for detecting TNT in contact with soil, based on Chemical PointDetection methodologies. FT-IR spectroscopy is used to provide information about identity and composition in very smallsamples or small heterogeneities in large samples. The main objective of this work is to study thevibrational behavior of TNT when in contact with soil that contains argillaceous minerals, specifically of thegroup of the smectites. Literature indicates that clays of this group present certain characteristics leadingto affinity to nitroaromatic compounds, such as TNT. The clay used in this investigation was saturated with potassium cations to increase the adsorption ofTNT on clay. The study includes the exposure of Clay/TNT mixtures to a series of environmentalvariables, which include: variation of alkalinity and acid content of the mixtures, variation of temperature,addition of water and explosive mass fraction in the mixture. Visible changes of color in the K-clay-TNT orNa-clay-TNT mixtures were observed but without displaying vibrational changes in highly basic clays.Under the environmental studied conditions, TNT infrared signals were highly persistent in soils, exhibitinga resistance to the effect of temperature, UV light incidence and water content in the soil. Studies revealedthat the characteristic vibrational infrared bands of TNT were not significantly shifted. The interaction withhomoionic montmorillonite clay is weak or non existent under the conditions studied. The main bands ofthe explosive prevail in the sample and are possible to distinguish the spectrum of clay component andthe one for the nitroexplosive. A band corresponding to umbrella deformation of the group methyl of theTNT is active when the explosive is added to the Na+-clay that has been treated with alkaline solution.This leads to speculate about certain type of interaction of the explosive with clay.

C3X-RAY PHOTOELECTRON STUDY OF RDX

Miguel A. González Santiago, Samuel Hernandez and Miguel E. Castro*Center for Chemical Sensor Development, Department of Chemistry, UPR-Mayagüez

Energetic materials have been used as explosives component of landmine, explosive plastic (C-4), andhome made bombs among others. Acquiring or access to the synthesis details of these materials isavailable on a click of a button. With constant terrorist threats within our societies; detection of thesematerials could play an important role on national security. Hexahydro-1,3,5 trinitro-s-triazine (RDX) is asecondary explosive which is the main component of C-4 explosive and others. Structural studies of RDXhave established the existence of two crystal morphologies, known as α-RDX and a less stable andunderstood β-RDX. The structural conformation of β-RDX has a Cs symmetry in which two of its nitrogroups are in an axial orientation while the third one is oriented equatorially. Meanwhile, a C3v symmetryfor α-RDX has been suggested due to either an all axial or all equatorial orientation of its three nitrogroups. The formation of RDX thin films and their vibrational studies has been reported. X rays are widely used in airports and other security checkpoints for the detection of nitro explosives.However, little photoelectron spectroscopy work has been performed on nitro explosives, probably due totheir high vapor pressure. In this work we report on X-ray photoelectron spectroscopy (XPS)measurements on films of RDX deposits on a silicon substrate surface. Deposits of RDX in acetonesolution (500 ppm) on a silicon substrate were prepared and allowed to evaporate at room temperatureopen to air. XPS measurements performed on the deposits reveal a broad (N1s) band between 403.375and 405.75 eV. The N1s binding energy increases slightly with the amount of RDX in the deposit. A highbinding energy peak around 411 eV is observed in high deposits of RDX. This band decreases with timeof the deposit in the vacuum system and may result from non accommodated RDX molecules oralternatively, to a new structure of RDX.*Corresponding author e-mail: mcastro@uprm.edu

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C6DETECTION OF NITRO-EXPLOSIVES BY ENHANCED RAMAN SCATTERING ON

NANOPARTICLE SUBSTRATES: Ag AND Au COLLOIDS AND Au-Ag ALLOYJackeline I. Jerez Rozo*, Ana Maria Chamoun, Joany Hernández and Samuel P. Hernández-

RiveraCenter for Chemical Sensors Development / Chemical Imaging Center

Department of Chemistry, University of Puerto Rico, Mayagüez, PR Surface-enhanced Raman scattering (SERS) combines extremely high sensitivity, due toenhanced Raman cross-sections comparable or even better than fluorescence emission, withthe observation of vibrational spectra of adsorbed species, providing one of the most incisiveanalytical methods for chemical and biochemical detection and analysis. SERS is a well knownprocess in which a normally weak process such as inelastic Raman dispersion, owing to itsscattering nature, becomes a relatively strong event. Roughened metal surfaces anddiscontinued or cluster-like particle can give way to a SERS active surface. A colloidalsuspension of zero oxidation state metals can also act as a SERS surface, in this case with theadded bonus of wet (aqueous media) chemistry capabilities. Nanoparticles are of fundamentalinterest since they possess unique size-dependent optical and chemical properties, which arequite different from the bulk and the condensed phase atomic state. The objective of this study is to modify silver and gold colloids by using variations in pH,concentration of the reducing agent and temperature of the preparation step for the colloidalsuspension. The nanoparticles used in this study were prepared by chemical synthesis:reduction in aqueous media. Inter-metal alloy type colloidal gold and silver nanoparticles wereprepared by successive reduction of the substrate and then of the covering metal. The colloidal suspensions were characterized using techniques such as UV-VISspectroscopy and Scanning Electron Microscopy (SEM). The colloids were used for thedetection of trace amounts of nitroexplosives with detection limits down femto-molarconcentration. TNT was excited at an incident wavelength of 785 and 532 nm and the spectrawere obtained in the 100-3500 cm-1 wavenumber range, using 10 scans and 30 seconds ofintegration time.

C5THEORETICAL AND EXPERIMENTAL VIBRATIONAL AND NMR STUDIES OF RDX

Ricardo Infante-Castillo*, and Samuel P. Hernández-RiveraChemical Imaging Center / Center for Sensors Development

Department of Chemistry, University of Puerto Rico, Mayagüez, PR The cyclic nitramine hexahydro-1,3,5-trinitro-s-triazine, commonly known as RDX, is apowerful secondary explosive that has attracted considerable attention due to its physicalproperties. The trinitrate ester is very persistent in the environment with an estimated lifetime of90 years, under varied soil conditions. Another property that has been the subject of severalinvestigations is the possible conformational arrangements that lead to polymorphism. Theconformers of RDX are distinguished mainly by the arrangement of the nitro groups relative tothe ring atoms of the RDX molecule. FTIR and Raman spectra of solid RDX and 13C enriched RDX are presented and assignedwith the help of the Density Functional Theory (DFT) calculations. Chemical shielding constantswere computed by Gauge Independent Atomic Orbital (GIAO) method for the β-RDXconformer. The data are compared with the experimental solid phase and solution data,focusing on the agreement the spectral patterns and spectral trends. The results of harmonicvibrational frequencies and absolute shielding (GIAO) calculations using DFT approximationsupported by experimental studies are also reported. The qualitative agreement between theexperimental and calculated values of the chemical shifts shed more light on the understandingthe basic shift-molecular structure relationship of RDX conformers.

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C8DETECTION OF NITRO-EXPLOSIVES BY ENHANCED RAMAN SCATTERING ON NANOPARTICLE

SUBSTRATES: Ag AND Au COLLOIDS AND Au-Ag ALLOYJackeline I. Jerez Rozo*, Ana Maria Chamoun, Joany Hernández and Samuel P. Hernández-Rivera

1Department of Chemistry, University of Puerto Rico, Mayagüez, PR2Department of Biology, University of Puerto Rico, Mayagüez, PR

Bioterrorism and its potential for mass destruction has been subject of increasing international concern. Only modestmicrobiologic skills are needed to produce and effectively use biological weapons. Production costs are low and aerosoldispersal equipment from commercial sources can be adapted for biological weapon dissemination. These prevailingconditions motivates the increased interest in the application of several physicochemical analytical techniques for therapid detection and identification of microorganisms. Raman spectroscopy and Surface Enhanced Raman Scattering(SERS) require minimum sample and allow for fast identification of microorganisms. The use of these techniques forcharacterization of the spectroscopic signatures of these agents and their stimulants has recently gained considerableattention due to the fact that these techniques can be easily adapted for standoff detection from considerable distances.The techniques also show high sensitivity and selectivity and offer near real time detection duty cycles. This research focuses in laying the grounds for the spectroscopic differentiation of Staphylococcus spp.,Pseudomonas spp., Bacillus spp., Salmonella spp., Enterobacter aerogenes, Proteus mirabilis, Klebsiella pneumoniae,and E. coli, together with identification of their subspecies. In order to achieve the proposed objective, protocols tohandle, cultivate and analyze the strains have been developed. Spectroscopic similarities and marked differences havebeen found for Spontaneous or Normal Raman spectra and for SERS using silver nanoparticles have been found. Theuse of principal component analysis (PCA), discriminate factor analysis (DFA) and a cluster analysis were used toevaluate the efficiency of identifying potential threat bacterial from their spectra collected on single bacteria. The DFAfrom the Raman spectra of the bacteria shows low discrimination between the diverse bacterial species. However, theresults obtained from SERS experiments demonstrate the technique to be one with high discrimination capability. Thespectroscopic study will be extended to examine the spores produced by selected strains since these are more prone tobe used as Biological Warfare Agents (BWA) due to their increased mobility and possibility of airborne transport. Microinfrared spectroscopy as well as fiber coupled FTIR will also be used as possible sensors of target biologicalcompounds.

C7THE ELECTRON CONDUCTION IN COLLOIDAL SYSTEM: A KINETIC STUDY OF AG2S SEMICONDUCTOR

NANOPARTICLE FORMATIONMadeline S. León-Velázquez 1, Roberto Irizarry 2 and Miguel E. Castro 1

1Chemical Imaging Center, Department of Chemistry, University of Puerto Rico, Mayagüez, PR2Research Triangle Park, Electronic Technologies, DuPont, Raleigh, NC

The synthesis of metal and semiconductor nanoparticles has received widespread attention by the scientific communitydue to the large number of technological applications they find in nanoscaled systems. The mechanism of nanoparticlegrowth is, in general, still an open question. A few studies have relied on the fluorescence of semiconductornanoparticles to monitor particle growth. These previous works have contributed significantly to the current body ofknowledge related to the mechanism of nanoparticle assembly. The general picture that emerges from these previousworks is that nanoparticles in solution form from the self assembly of atoms and nuclei in solution. The driving forcesinvolved in this self assembly are not well known. There is little doubt that electrostatic and magnetic interactionsamong atoms and small nuclei play an important role in nanoparticle synthesis and growth. The purpose of thiswork is to explore on the use of real time-conductivity measurements as an alternative tool to measure the kinetics ofnanoparticle growth. Electron conduction in colloidal systems is typically thought of as resulting from electron hoppingfrom one component to another in solution. Such electron conduction reflects then the electrical stability and order ofthe colloid, which are well known to result from a delicate balance of electrostatic and magnetic forces. For thispurpose, we have focused on the synthesis of Ag2S from the reaction of silver cations, Ag+, with sulfide anions, S-2.Ag2S semiconductor nanoparticles absorb light deep in the UV (about 230-240 nm) and exhibit a strong fluorescence inthe visible at low temperatures. Conductivity measurements on this synthesis are an attractive approach to study themechanism of nucleation. In this work a stopped flow system is used to study reaction growth kinetics of the formationof Ag2S nanoparticles. The kinetic data obtained indicates that the reaction mechanism involves multiple steps or asquare root dependence of k on concentration must be taken into account in the quantitative analysis of the dataformation. Conductivity and optical absorption measurements indicate that the semiconductor, nucleation andcoalescence of particles occur in a time scale shorter than 5 seconds after the flow of Ag+ and S-2 is brought to a stop.

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C10DETECTION OF CHEMICAL WARFARE AGENTS SIMULANTS (CWAS) USING FIBER OPTIC COUPLED

GRAZING ANGLE PROBE-FTIRDeborah Nieves, Oliva M. Primera-Pedrozo,Leonardo Pacheco-Londoño and Samuel P. Hernandez-Rivera,

Chemical Imaging Center / Center for Sensors Development, Department of Chemistry,University of Puerto Rico, Mayagüez, PR

Since September 11, 2001 the world focuses their attention on the possibility of use of chemical and biologicalthreat agents by terrorist organizations directed against troops and/or civilians. Countering future attacks requires awide array of detection capabilities for range of potential deployment scenarios. For the verification of the presence ofCWA it is necessary to detect these compounds or their degradation products on the surfaces on which they havesettled or condensed. Electrospray Ionization (ESI)-MS has been used for the detection of CWA in water, but theability of Grazing Angle Probe-FTIR to detect CWA and their degradation products deposited on surfaces has notbeen investigated. This paper focuses on the measurement of spectroscopic signatures of Chemical Warfare Agent Simulants(CWAS) using vibrational spectroscopy. Fiber Optic Coupled-Grazing Angle Probe-FTIR was used to characterize thespectroscopic information of target threat agents simulants: 2-chloroethylethyl sulfide (2-CEES), dimethylmethylphosphonate (DMMP), triethylphosphate (TEP), di-isopropylmethyphosphonate (DIMP), as detected on stainless steelsurfaces. Limits of detection (LOD) that can be achieved could be as low as nanograms/cm2 (milligrams/m2). The limitingfactors are physical properties of the target compounds such as high vapor pressure and low surface adhesion. Forthe four CAWS analyzed, 2-chloroethyl ethyl sulfide (2-CEES) has the lowest limit of detection with 5.1 ug/cm2.Comparing the Fiber Coupled-GAP-FTIR spectra obtained with KBr cell spectra measured in a bench instrumentleads to the conclusion that they are identical. This methodology can be applied for detecting CWA on surfaces suchas metals, plastics, glass, wood and others. Other application of the technique in the area of chemical agents is insurface decontamination and cleaning validation of these highly toxic and polluting compounds.

C9NORMAL RAMAN AND SURFACE ENHANCED RAMAN SPECTROSCOPY DETECTION OF BIOLOGICAL

AGENTSTatiana Luna-Pineda1, Kristina Soto-Feliciano2, Edwin De La Cruz-Montoya1,

Carlos Ríos-Velázquez2 and Samuel P. Hernández-Rivera11Department of Chemistry, University of Puerto Rico – Mayagüez, PR

2Department of Biology, University of Puerto Rico – Mayagüez, PR

Bioterrorism and its potential for mass destruction has been subject of increasing international concern. Onlymodest microbiologic skills are needed to produce and effectively use biological weapons. Production costs are lowand aerosol dispersal equipment from commercial sources can be adapted for biological weapon dissemination.These prevailing conditions have motivates the increased interest in the application of several physicochemicalanalytical techniques for the rapid detection and identification of microorganisms. Raman spectroscopy and SurfaceEnhanced Raman Scattering (SERS) require minimum sample and allow for fast identification of microorganisms. Theuse of these techniques for characterization of the spectroscopic signatures of these agents and their stimulants hasrecently gained considerable attention due to the fact that these techniques can be easily adapted for standoffdetection from considerable distances. The techniques also show high sensitivity and selectivity and offer near realtime detection duty cycles. This research focuses in laying the grounds for the spectroscopic differentiation of Staphylococcus spp.,Pseudomonas spp., Bacillus spp., Salmonella spp., Enterobacter aerogenes, Proteus mirabilis, Klebsiellapneumoniae, and E. coli, together with identification of their subspecies. In order to achieve the proponed objective,protocols to handle, cultivate and analyze the strains have been developed. Spectroscopic similarities and markeddifferences have been found for Spontaneous or Normal Raman spectra and for SERS using silver nanoparticleshave been found. The use of principal component analysis (PCA), discriminate factor analysis (DFA) and a clusteranalysis were used to evaluate the efficiency of identifying potential threat bacterial from their spectra collected onsingle bacteria. The DFA from the Raman spectra of the bacteria show low discrimination between the diversebacterial species. However, the results obtained from SERS experiments demonstrate the technique to be one withhigh discrimination capability. The spectroscopic study will be extended to examine the spores produced by selectedstrains since these are more prone to be used as Biological Warfare Agents (BWA) due to their increased mobility andpossibility of airborne transport. Micro infrared spectroscopy as well as fiber coupled FTIR will also be used aspossible sensors of target biological compounds.

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C12DEVELOPMENT OF SPME-HPLC METHODOLOGY FOR DETECTION OF NITROEXPLOSIVES

Sandra Peña*, Edwin de la Cruz, Samuel P. Hernández-RiveraCenter for Chemical Sensors Development / Chemical Imaging Center

Department of Chemistry, University of Puerto Rico, Mayagüez, PR

Solid phase microextraction (SPME) has been coupled with liquid chromatography to widen its range ofapplications to nonvolatile and thermally unstable compounds, generally limited for SPME-GC. A methodof analysis of nitroaromatic explosives and their degradations products was developed using SPME andhigh performance liquid chromatography with ultraviolet detection (HPLC-UV), introducing a modifiedinterface that ensured accuracy, precision, repeatability, high efficiency, unique selectivity and highsensitivity to detection and quantification explosives from surface soil samples. A pretreatment step wasintroduced for the soil samples which extracted the target compounds into an aqueous phase. Severalparameters that affect the microextraction were evaluated such as fiber coating, absorption anddesorption time, stirring rate and effect of NaCl concentration on analyte extraction. The effects of differentsolvents on SPME fiber were also evaluated. Carbowax-templated resin (CW-TPR) andpolydimethylsiloxane-divinylbenzene (PDMS-DVB) fibers were used to extract the analytes from theaqueous samples. Explosives were detected at parts per million concentrations. This work confirms thatSPME-HPLC is a very attractive and promising method and has great potential in the analysis of theexplosives from aqueous samples and has been successfully applied to the determination of nitroaromaticcompounds.

C11DETECTION OF EXPLOSIVES BY STANDOFF INFRARED AT LABORATORY SCALE

Leonardo Pacheco-Londoño1,*, Oliva M. Primera-Pedrozo1 and Samuel P. Hernández-Rivera1Chemical Imaging Center / Center for Sensors Development

Department of Chemistry, University of Puerto Rico, Mayagüez, PR

After four years of operation in a Chemical Point Detection (near field, under microscope) Detection ata Distance experiments have been designed and are under development at the Center for SensorsDevelopment at UPRM. An actively operated standoff infrared detection system was designed fromcommercial infrared equipment: a bench interferometer, an external mirror used to guide an uncollimatedIR beam and an external cryocooled MCT detector. This setup has been implemented as a stepping stoneto a full fledged, telescope based commercial FTIR system, in order to justify its acquisition by Defenseand Security agencies. Experiments were done by IR detection of high explosives RDX and TNT on reflective surfaces. In thedetection on surfaces, samples were moved to different distances and a beam of infrared light wasreflected on a metallic surface at an angle close to 0° (backward collection from surface normal). Firstsamples containing surface loadings of 2 to 30 mg/cm2 of high explosives (TNT and RDX) werecharacterized after depositing on reflective stainless steel surfaces using Reflection-Absorption InfraredSpectroscopy (RAIS). Uniform surface coatings were achieved by transferring samples of desiredconcentration by pipetting and then spreading the solution by smearing. Targets were first measured at 3feet from the IR source and then moved to increasing distances: up to 12 feet and remote-sensed spectrawere collected in active reflectance mode. The spectroscopic window of 1500-1340 cm-1 was used to analyze TNT reflectance spectra atdistances of 3, 6, 9 and 12 feet. The wavenumber range covered both the asymmetric and the symmetricNO2 stretches in the nitroaromatic molecule. No other data preprocessing algorithms were applied to TNTspectra. Low limits of detection (LLD) were determined from standoff reflectance spectra using signal tonoise ratios = 2.5. At source-target distance of 20 feet, LLD were 18 and 20 mg/cm2 for TNT and RDX,respectively. The limits of detection were determined by calculating the signal to noise (S/N) ratios. Whenthe sampling distance increased, the values of S/N diminished drastically. The maximum values obtainedfor S/N for TNT at very short distances (3 feet) approached the minimum values quickly, when thedistance increased. At long distances (9 and 12 feet) it was difficult to decide the detection limits becausethe values of S/N for these distances were very close in range.

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C14PHOTODEGRADATION KINETICS OF EXPLOSIVES WITH TiO2 NANOPARTICLES

Gabriel Perez*, Edwin De La Cruz, Victor De La Cruz, Leonardo C. Pacheco and Samuel P. Hernández-RiveraCenter for Chemical Sensors Development / Chemical Imaging Center

Department of Chemistry, University of Puerto Rico, Mayagüez, PR The degradation of toxic chemical compounds in water is one of the most important challenges in the control of thecontamination of the environment. The primary source of the majority of the pollutants is of industrial and militarynature but other important sources are in our own homes. For this reason, the study of new oxidation processes orimprovements in existing routes for the destruction of these compounds is of world-wide interest. The production,testing and use of high explosives from the late 19th century to date has extensively contaminated soil and water at alarge number of government installations. Some of these high explosives are toxic and mutagenic and classified as anenvironmental hazard and as priority pollutants by US EPA. In the early 20th century, scientists developed more than60 high explosives compounds (HEC). The predominant HEC for military purposes are the nitroaromaticcompounds: 2,4,6-trinitrotoluene (TNT), 2,4-dinitrotoluene (DNT), 2,6-dinitrotoluene (DNT), and their precursors anddegradation products: 1,3-dinitrobenzene, 1,3,5-trinitrobenzene, 4-amino-2,6-dinitrotoluene and 2-amino-4,6-dinitrotoluene. One of the most pertinent investigations in these technological areas is the application of solar energy in thephotodegradation of organics compounds. Photocatalysis: a catalytic process provided by radiant energy, with awavelength that is capable of exciting a semiconductor (catalytic agent), generally a metallic oxide, to the degree thatmakes the material to behave as a conductor on the surface or interfacial region between solid and the solution,where the reaction develops a Redox process. The photocatalytic treatment of water with TiO2 is efficient for thedestruction of many organic pollutants, including chlorinated compounds. The photocatalytic degradation rate ofdifferent compounds depends on various parameters, such as temperature, pH, initial concentration of the pollutant,TiO2 particles size, light intensity and chemical nature (structure) of the target compounds, among others. The photocatalytic degradation of TNT in a reactor, using a UV lamp as a light source and TiO2 as a photocatalystwas investigated. The percentage decrease in TNT concentration, resulting from photocatalytic reactions conductedfor 140 min was 70%. The reaction rate was found to follow pseudo first order kinetics, represented by the Langmuir-Hinshelwood model. In this case, a constant of reaction rate k= 1.67 [mg/L-min] and an equilibrium adsorptionconstant K= 1.5 * 10-2 [L/mg] were found.

C13CHARACTERIZATION AND DIFFERENTIATION OF HIGH ENERGY AMINE PEROXIDES BY DART-TOF-MS AND

VIBRATIONAL MICROSCOPYAlvaro J. Peña-Quevedo[1],*, Robert B. Cody2, Nelmary Rodríguez1, Deborah Nieves1, Miguel Castro-Rosario1,

Nairmen Mina-Camide1,and Samuel P. Hernández-Rivera1,*1Chemical Imaging Center / Center for Sensors Development

Department of Chemistry, University of Puerto Rico, Mayagüez, PR 006812JEOL USA, Inc., 11 Dearborn Road, Peabody, MA 01960

Increases in terrorist acts using home-made explosives have forced federal and international agencies to developmethodologies for novel or unknown energetic compounds. Triacetone Triperoxide (TATP) and HexamethyleneTriperoxide Diamine (HMTD) are the most used compounds as well as the most studied peroxides for in situ terroristattempts. There are others peroxides that do not have any method reported for their detection. This study presentsthe first method of detection for Tetramethylene Diperoxide Dicarbamide (TMDD) and other nitrogen based peroxidesusing novel and common methods, such as Raman Spectroscopy and Direct Analysis in Real Time (DART)-TOFMass Spectrometry. Synthesis and characterization of hexamethylene triperoxide diamine (HMTD), tetramethylene diperoxidedicarbamide (TMDD) and tetramethylene diperoxide acetamide (TMDA) using DART-TOF, FT-IR and RamanMicroscopy have been carried out. Mass fragmentation patterns for HMTD in DART-TOF are consistent with othermass spectrometric studies and commercial standards. TMDD showed a base peak of 59 m/z, and othercharacteristic peaks, but no molecular peak present using DART. Vibrational spectroscopy was used to characterizeand distinguish the peroxides synthesized from their precursors. HMTD and TMDD were fully characterized by theperoxide bands between 750-900 cm-1 and these results are comparable with previous documented data in otherperoxide compounds. TMDD has been identified and characterized by its distinctive bands for n(N-H) and n(C=O).Differentiation spectroscopy studies were also conducted. In these studies the differences in the n(O-O), n(N-C), n(C-O), d(CH3-C) and d(C-O) bands for Raman and IR were established. A new compound from acetamide wassynthesized and characterized by vibrational spectroscopy.

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C16ADSORPTION COEFFICIENTS FOR TNT-SOIL AND TNT-CLAY INTERACTIONS

Rosángela Rivera1, Miguel A. Muñoz2 and Nairmen Mina1

1Department of Chemistry, University of Puerto Rico, Mayagüez, PR2Department of Soil and Agronomy, University of Puerto Rico, Mayagüez, PR

TNT is an energetic compound and the least mobile of the military explosives. It is one of the largestsoil contaminants. In this research, the adsorption behavior of TNT was evaluated in soil samples fromhorizons Ap and A from Jobos Series at Isabela, Puerto Rico. The mechanical method was used toseparate the clay fraction from the other soil components. Using the hydrometer method the particlesize distribution for the soil horizons was obtained. Physical and chemical characterization studies suchas cation exchange capacity (CEC), surface area, percent of organic matter and pH were performed forthe soil and clay samples. A complete mineralogical characterization of clay fractions using X-raydiffraction analysis revealed the presence of kaolinite, goethite, hematite, gibbsite and quartz. In orderto obtain adsorption coefficients (Kd values) for the TNT–soil and TNT-clay interactions highperformance liquid chromatography (HPLC) was used. The adsorption process for TNT-soil wasdescribed by the Langmuir model. The higher adsorption was observed in Ap horizon (83 ± 6 L/Kg). Onthe other hand, the Freundlich algorithm described the adsorption process for TNT-clay. The relativeadsorption capacity of the clays for TNT were higher in the A horizon (109 ± 13 L/Kg). These resultssuggest that adsorption by soil organic matter predominates over adsorption on clay minerals whensignificant soil organic matter content is present. It was found that, properties like cation exchangecapacity, surface area, type of exchangeable cations and clay minerals present in the clay fractions areimportant factors in the adsorption of clayey soils.

C15TOWARD REAL TIME MONITORING OF NON-FRIENDLY CHEMICALS IN THE ENVIRONMENT: A

NIR STUDY OF NITRO ORGANICSCarlos Peroza, Marissa Morales, Leo Pacheco, Raquel Feliciano,

Samuel Hernández and Miguel Castro*Chemical Imaging Center and Center for Chemical Sensor Development, Department of Chemistry,

University of Puerto Rico, Mayagüez, PR

Many of the current strategies for detection of explosives are based on vibrational spectroscopy. Alarge body of works related to the use of Raman of mid infrared exists while near infrared (NIR)spectroscopy has received little attention. The NIR region is dominated by bands due to combinationsand overtones of vibrational modes typically observed in mid IR measurements. Such combinationscan result in an increase in selectivity of one given type of chemical in a complex environment.Furthermore, since the vibrational fingerprint is sensitive to the structure of the different forms of agiven molecule, the NIR spectra may be used to distinguish among the different forms of a givenmaterial. In this work, we present a systematic study on the use of NIR for the characterization of aseries of structurally related nitro organics with the purpose of contributing to the current body of workin the detection of NO2 containing explosives. The NIR of 2-4 dinitrotoluene, 2,6-dinitrotoluene,trinitrotoluene, toluene, and 2,4 dinibenzene are compared. It is found that the NIR spectra of thesechemicals are markedly different in the first overtone region as well as in the region that corresponds tothe first and second combination bands. For TNT, the limit of detection has been established to be afew micrograms for the crystalline: no NIR bands are observed in the amorphous form of the material.The potential of NIR spectroscopy to monitor environmentally hazardous materials like the nitroorganics listed previously will be discussed.*Corresponding author e-mail: mcastro@uprm.edu

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C18SCANNING TUNNELING ELECTRON MICROSCOPY STUDIES OF Ru NANOSTRUCTURES

Priscila Santiago, Miguel Santiago and Miguel Castro*Chemical Imaging Center, Department of Chemistry, Mayagüez, PR

Metallic structures are being widely studied because of the different properties they posses at thenanoscale level. One of the most important of these properties is the catalytic activity, which is necessarywhen the nanostructures are used in systems such as fuel cells. The synthesis of ruthenium nanostructureshas been scarcely reported, and their characterization has been made by different methods such astransmission electron microscopy, which does not present clear morphology images. Rutheniumnanostructures in an ethylene glycol solution were prepared. A polymer was used to support the structures,and the reduction of the Ru3+ compound was observed. Scanning tunneling microscopy, a powerfulanalytical tool, was used to characterize the structures. Valuable information about their morphology andsize was obtained. Tunneling current (I) as a function of bias voltage (V) spectroscopy measurements wereperformed to compare the particles before and after soft annealing of the particles. Well defined bands areobserved in the I-V measurements. It is believed that the information obtained may be useful for theapplication of these structures in fuel cells’ processes and in the synthesis of alloys of Ru and other metalsused as catalytic agents.*Corresponding author e-mail: mcastro@uprm.edu

C17FIBER OPTIC COUPLED GRAZING ANGLE PROBE-FTIR DETECTION OF 2,4,6-TRINITROTOLUENE

ON SURFACESNelmarie Rodríguez –Cardona, Oliva M. Primera-Pedrozo, Leonardo Pacheco-Londoño

and Samuel P. Hernandez-RiveraCenter for Chemical Sensors Development / Chemical Imaging Center

Department of Chemistry, University of Puerto Rico, Mayagüez, PR

With heightened awareness of Homeland Security issues, the detection of explosives has become a toppriority. Explosive compounds need to be detected on a variety of surfaces. Every surface will interact withthese organic compounds and the degree of adhesion will vary from one surface to another. Fiber OpticCoupled-Grazing Angle Infrared Spectroscopy has been used as a potential technique to develop newmethodologies for detection of explosives on surfaces. The current method is remote sensed, in situ andcan detect as low as nanograms/cm2 (mg/m2) of the compounds. Smearing technique and thermal inkjet(TIJ) technology are used for transferring the target analyte on the substrates to be used as standards.Explosives detection is a very important task for National Security. The formidable task includesdevelopment of new probes and methods for detection of concealed explosives. One of the most relevant areas of investigation is to analyze 2,4,6-trinitrotoluene (TNT) on several nonconventional and low reflection surfaces, such as plastics and glasses. It is also important to optimize forsample collection conditions where more accurate spectra are obtained and better pre-processingconditions can be achieved. Several aspects can affect these two related aspects of the methodology. Forinstance, the distance between the mirrors and the plate affects the spectral intensity. For this reason it wasimportant to determine a distance where the spectra are obtained more accurately, which was measured tobe 5 cm. Another aspect affecting intensity of TNT peaks is the solution concentrations shown that whenthe concentrations are lowered the less TNT signals were observed (for example at 78 ng/cm2 the signalswere nearly completely attenuated). A series of statistical methods can be used for detection andquantification of TNT dissolved on dichloromethane on plastic surfaces. Surface detection by areaintegration and surface detection by Partial least squares (PLS). PLS regression is an extension of themultiple linear regression models.It was observed in the spectra obtained that TNT peaks heights decreased with surface loadings in aregular manner. The loading concentration of 0.63 mg/cm2 was considered as limit of quantification and0.15 mg/cm2 as limit of detection for area integration. On the other hand, a loading concentration of 0.16 mg/cm2 was considered as limit of quantification and 0.078 mg/cm2 as limit of detection for PLS analysis.

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C20DISSOCIATION CONSTANTS OF ACETIC ACID IN 15 AND 35 W/W % ISOPROPANOL-WATER

SOLVENT FROM 5 TO 35OC AT TEN DEGREES INTERVALSEmlyn Vélez1, Damian Reyes1 and Carmen A. Vega2 *

1Department of Chemical Engineering, University of Puerto Rico, Mayagüez, PR2Department of Chemistry, University of Puerto Rico, Mayagüez, PR

The values of standard potential of the silver/silver chloride electrode in 2-propanol+water wererequired in order to determine the dissociation constants of acetic acid in mixtures of 2-propanol-watersolvent. Standard potentials for silver/silver chloride necessary for the calculations of these experimentswere determined by extrapolation of experimental data from previous investigations at 25 and 50 W/W %2-propanol-water mixtures at the working temperatures. The electromotive forces (Emf) of galvanic cells (without transfer), which contain acetic acid in molalconcentrations from 0.01 to 0.1 as the electrolyte solution in 15 and 35 W/W % 2-propanol-water solventwere measured using a BX Precision 5492 5 ½ digit multi-meter. The silver/silver chloride electrodes wereprepared in the laboratory using the thermal-electrolytic type of procedure. The hydrogen electrodes wereprepared by electrode deposition of platinum in the two centimeters square platinum plate using a 3.5 percent (w/v) solution of chloroplatinic acid. The data were used to derive the standard changes of Gibbsenergy, enthalpy, and entropy for the acetic acid dissociation processes in these solvent mixtures.*Corresponding author e-mail: cvega@uprm.edu

C19TEMPERATURE DEPENDENCE OF THE LIMITS OF DETECTION OF TNT ON METALLIC SURFACES

USING FIBER OPTIC COUPLED-FTIRYadira Soto –Feliciano, Oliva M. Primera-Pedrozo*, Leonardo Pacheco-Londoño and

Samuel P. Hernandez-RiveraChemical Imaging Center / Center for Sensors Development

Department of Chemistry, University of Puerto Rico, Mayagüez, PR

Fourier transform infrared (FTIR) spectroscopy has been established as well suited for work outsidethe confinement of the sample compartment, provided the excitation source and the reflected light can betransported to the interferometer. Fiber optic cables that transmit in the Mid-IR range have made thispossible by allowing the development of a series of spectroscopic probes for in situ analysis. In previouswork it was established that surface concentrations of TNT as low as 0.3 mg/cm2 (300 ng/cm2) could bedetected with high confidence level. This limit of detection (LOD) varies according to familiar macroproperties. Vapor pressure, physical adsorption, sublimation rate and surface-adsorbate thermodynamicscan influence the detection limit. A close relation between vapor pressure and limit detection is shown for nitroexplosives. The amountof explosive and the residence time on stainless steel depends on this property, because at low surfacecoverage the explosive goes to the vapor phase fast. Loading concentrations near the limits of detectionwere prepared and spectra were recorded at different temperatures in the range of 14-30°C. Thesymmetric stretch of the nitro group was monitored for the experiments and the data were analyzed byusing peak areas and Chemometrics. A close relationship between the detection limit and temperaturewas observed. After generating the Partial Least Squares (PLS) model for each temperature in the form ofpredicted loading concentration values vs. true loading concentration values, the standard deviation andthe mean of the predicted values were calculated. An alternative method of computing the LOD isproposed, using standard deviation of each loading concentration and the mean of predicted loadingconcentration (M, mg/cm2): Standard deviation (SD) divided by the mean (M) of the series ofmeasurements multiplied by 100. Chemometrics routines were applied as data enhancers in order to fully accomplish the difficult taskproposed. Relative standard deviation allowed calculating the LOD and limit of quantification (LOQ) andtheir temperature dependence. For concentrations lower 2 ng/cm2 TNT could not be detected using usedfiber optic coupled FTIR at 14, 18, 26 and 30°C. It was possible to calculate the LOQ. This value was 10ng/cm2 for the all temperatures studied. This method promises to be an excellent way to calculate LOQand LOD for other nitroexplosives.