Peer Reviewed: Urban Air: Real Samples for Undergraduate Analytical Chemistry

4 6 0 A A N A LY T I C A L C H E M I S T R Y / J U LY 1 , 2 0 0 0

GGeneral agreement exists that the content of today’s

undergraduate analytical chemistry courses must be

more relevant to modern analytical laboratory prac -

tices (1). The current gap between “real work” experiences

and university training in analytical chemistry has raised con-

cerns among educators (1, 2). For example, Christian has found that,

based on surveys of modern analytical chemistry texts and under -

graduate courses, a typical first-year or sophomore analytical chemistry

course uses a text that covers gravimetric and volumetric methods,

acid–base equilibrium, spectrophotometry, potentiometry, and sepa-

ration techniques (1). Course content varies at institutions, but these

areas are included among the top 50% of topics usually covered at the

undergraduate level. This is antiquated. In preparing for industrial ca-

reers, today’s students need a broader range of technical and non -

technical skills (2), and their ability to think critically, communicate ef-

fectively, and work as a team to solve problems must be improved.

Urban Air:

Wilbert W. Hope Leon P. Johnson

Medgar Evers College

Photography by Rick Reinhard

Urban Air:Real Samples for

Undergraduate

Analytical Chemistry

Herbert Edwards, Deon Hines, and Wilbert Hope test for volatileorganic compounds (VOCs) atop a Brooklyn building.

Students learn analytical

chemistry by addressing

urban environmental issues.


In addition, educators say that increased emphasis shouldbe placed on how analyte structure and composition can be translated into transducer-generated information (howspectra, chromatograms, voltammograms, etc are generatedelec tron ically) (1). The concern is that by including moreinformation about instrumental techniques at the under -grad uate level, important fundamental information that isnow part of traditional quantitative analysis courses wouldbe eliminated, especially if extensive hands-on experienceis provided.However, Wenzel has shown that undergraduate analyt-

ical chemistry can be updated without sacrificing importantfundamental information (3, 4). Using group-learning andproject-based approaches, essential traditional content areascan be maintained, while further principles governing cur-rent analytical instruments are incorporated. At the sametime that students are acquiring the necessary laboratoryskills and theoretical knowledge, they can learn about envi-ronmental issues of community concern. For example, an instrumentation course offered at Loyola University ofChicago focuses on a single analyte—lead (5).The new B.S. degree program in environmental science at

Medgar Evers College located in New York City’s Brook-lyn section, focuses on the urban environment and hasadopted a similar approach. We describe here our efforts to use project-based activities and in corporate studies ofambient and indoor air into the laboratory sections of twoundergraduate analytical chemistry courses, quantitativeanal ysis (QA) and environmental meas urements and instru-mentation (EMI). Standard analytical methods have beenused or adapted as needed for laboratory experiments toallow students to analyze volatile organic compounds (VOCs)and airborne particulate matter. The course requires studentsto discuss health issues of concern to urban communities.In some cases, students’ investigations provide useful datafor more elaborate research projects. A project-based ap-proach can be readily adapted to suit inner-city collegeswith limited resources.

Building confidenceQAthe prerequisite for the EMI courseis offered to stu-dents who have completed a year of general chemistry. Upto 12 students per semester are enrolled in this four-creditcourse. One two-hour lecture and two three-hour labora-tory sessions per week are arranged to typically accommodatenine students who work full- or part-time and commute to campus daily. To achieve the QA course content goalsand objectives, we offer traditional class topics but modifythe six-hour laboratory section to include project-based ac-tivities that require student involvement in sampling andanalysis of indoor and outdoor air. The laboratory sectionis divided into traditional and project-based experiments.The traditional QA laboratory section consists of about

eight experiments per semester on gravimetric analysis,

titrations, colorimetric analysis, atomic absorption, TLC, andGC. Although the skills acquired in this setting may notbe readily applicable in most modern laboratories, we be-lieve that students should master these classical techniquesto increase their appreciation for and understanding of theevolution of analytical methods.Our laboratory course starts with five traditional experi-

ments that are completed in the first 6−7 weeks of a 14-weeksemester. Students prepare laboratory reports based on ex-periments that familiarize them with the laboratory environ -ment, fine-tune their laboratory and technical writing skills,and increase their awareness of laboratory safety. This periodbuilds the students’ confidence and independence, whichare required for the second part of the laboratory course.

Students (left to right) Deon Hines, Herbert Edwards, and Delray Burnett collect samples and observe the temperature of ambient air from a Brooklyn neighborhood.

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The second part of the laboratory course, worth 40% ofthe grade, consists of a small project requiring students tomake quantitative measurements of pollutants in urban air(Box 1). Students are given a laboratory manual describ-ing the experiments and project areas. The class is dividedinto small groups who choose one of three possible projects(Box 2). Each project requires students to set up air sam-pling units, monitor airflow through a filter membrane orreagent solution, and subsequently analyze the membraneor solution contents in the laboratory. Two air samplingunits, or “trains”, are run simultaneously in the same roomfor duplicate samples. The projects are discussed, and students form teams based

on their interest. By the fifth week of the course, study teams

are formalized, and each meets with the instructor to discussits project. The students conduct literature and Internetsearches and are required to find an EPA method and/orone recently published relevant article. They are also ad-vised to keep a separate journal of their project activities.During the sixth and seventh weeks, the instructor meets

with each group to ascertain its progress. Usually, little ifany project-related material has been read by this time, andmore precise directions for finding relevant literature aregiven to each group. By the eighth or ninth week, studentsare conducting in-lab practice runs and setting up samplingtrains, ensuring that they are easily transportable betweentest sites. Laboratory air is analyzed to provide baseline datafor making comparisons and ensuring complete familiariza-

tion with analysis instrumentation. In most cases, the ana-lytical methods are adapted from standard methods recog-nized by EPA, the American Society for Testing and Mate-rials (ASTM), or recently published papers.

Mercury in the airA recent survey indicates that segments of New York City’spopulation use mercury during religious practices (6). Amongthe Latin American and Caribbean community especially,mercury is believed to bring good fortune to those who useit. Brooklyn residents were asked by students to volunteertheir homes for indoor air sampling. Students comparedmercury levels in homes in which mercury use was suspect-ed with homes where mercury was not used. Indoor air was sampled by bubbling it through an acid

potassium permanganate solution. This procedure trappedvolatile elemental mercury by oxidizing it to Hg2+ (7). Mer-cury trapped in solution was determined by cold vapor atom-ic absorption. Although levels found in all homes were belowthe Occupational Safety and Health Administration (OSHA)limit, levels of mercury in the homes of suspected mercuryusers were more than twice that of nonuser residences.

Questions raised during informal discussions between thestudents and the instructor and during formal classroom pre-sentations provided teaching and learning opportunities thatare unique to this approach and foster the students’ appreci-ation of analytical chemistry in daily life. Two questions wereraised at the conclusion of this particular exercise: Is concernabout the religious use of mercury justified, since mercurylevels in all homes were below the OSHA limit? Do elevatedmercury levels in the homes of suspected users present anyhealth risks? During class discussions, students also consid-ered the relationship between the number of samples anderror magnitude, the need for quality control, and what itwould take to answer questions raised by EPA.

Aldehydes and ketonesUsing EPA Method T05 (8), formaldehyde, acetone, ac-etaldehyde, and benzaldehyde were identified at levels belowthe OSHA limit in reprographic rooms and in a Brooklynfurniture store. Although no previous complaints weremade about the air quality in these rooms, we expectedthat quantitative determination of these compounds in in-door air would prove a novel experience. Students expect-

Box 2. Content of QA course

Class topicsQuantitative versus qualitative analysisSteps in quantitative analysisStatisticsStoichiometric calculationsGravimetric analysisVolumetric analysisChemical equilibriumPotentiometrySpectrophotometryExtraction and separationIntroduction to chromatographyLaboratory experimentsGravimetric determination of chlorideIodometric titration: Analysis of commercial hypochlorite

or the Kjeldahl method for the determination of nitrogen in food

Potentiometric measurements: pH titrationDetermination of lead on the surface of leaves (colorimetric

measurements)Determination of mercury in water by cold vapor AADetermination of trihalomethanes in drinking waterProjects (one project per group)Determination of mercury in indoor air by nonflame AA (cold

vapor AA)Determination of aldehydes and ketones in indoor air (HPLC)Determination of lead in indoor particulate (flame AA)

Box 1. Urban air

Particulate matter and volatile organic compounds (VOCs) consti-tute complex mixtures of airborne pollutants. They are emittedfrom natural and anthropogenic sources, mainly from fossil fuelburned by electrical utilities, industries, and motor vehicles. Parti-cle concentrations in the urban atmosphere are more than 50%higher than those in rural or so-called clean suburban atmospheres(12). Transportation and other fuel combustion processes accountfor 62.9% of fine particles (<10 µm) from traditionally inventoriedsources and 39.6% of all VOCs (13). The Brooklyn area is subject-ed to 241 tons of VOC emissions annually (14). How do these esti-mates relate to the quality of the air that individuals in inner-citycommunities breathe?

Mortality and morbidity due to asthma and other lung diseases inthe inner cities are above the national U.S. average. These increasesare linked to higher levels of ambient and indoor air pollution. Inhala-tion of fine particles, ozone, oxides of nitrogen and sulfur, VOCs, andother chemical agents have all been shown to worsen asthma andincrease bronchial hyperactivity (15–17). A large portion of aerosolsfound outdoors penetrate indoors and become trapped, causing in-door air pollution levels to be greater than outdoor levels. Moreover,inner-city residents spend 80−90% of their time indoors (18).

Global and regional climatic conditions are also affected by at-mospheric aerosols. Particles in the troposphere scatter solar ra-diation, trap greenhouse thermal radiation, alter the amount of lightreflected by the Earth, and increase the stability and brightness ofthe clouds. In addition, atmospheric aerosols contribute to acidrain and visibility impairment (19).



ed their results to conform to the OSHA limit. However,in one experiment, two sampling trains at different loca-tions in the same reprographic room produced markedlydifferent results: A significant amount of an unidentifiedcompound was found in one sampling position, but nosuch compound was found in the other location.To understand why the unidentified compound was found

in only one section of the room, students had to examinethe different types of chemicals used in printing and photo -copying, as well as the way these chemicals were handled andstored. They determined that the sampling train that pickedup this unidentified compound was placed on a table, whichhad chemicals stored underneath it. The spirited discussionsthat ensued enriched the project. The students discussedthe principles of environmental sampling and consideredhow the storage of the chemicals affected the sampling.

Measurements and instrumentationAfter completing the QA class, environmental science ma-jors take EMI (Box 3), which is offered as a three-creditenvironmental science course, half in-class work and halflaboratory work. The first six weeks are devoted to class

lectures and discussions covering classical versus instru-mental methods, environmental sampling, extraction andseparation techniques, and principles of analytical instru-mentation. In addition, depending on the focus of thecourse, students collect field samples of air, water, or soil.Students are encouraged to relate their experiences withtheir laboratory projects, which establishes continuity be-tween the two classes.For example, when reviewing environmental sampling

procedures, each group is required to prepare an environ-mental sampling plan for a fictitious project. Those stu-dents previously involved in QA can better appreciate theneed for a sampling plan and can list some important fac-tors to consider when preparing one. Basic principles, in-cluding how representative the sample is, how dependentsampling and analysis are on each other, the end-use ofthe data (data quality objectives), and the need for qualitycontrol samples, are explained in the context of students’experience with previous laboratory projects.Analytical facilities include an HPLC, a GC-ECD, an

atomic absorption (AA) spectrophotometer, an FT-IRspectrophotometer, and a GC/MS. A purge-and-trap unitis attached to the GC/MS. To cover some techniques andinstruments that are not part of our analytical facilities,class groups are required to search the literature and givepresentations on supercritical fluid chromatography, radio-chemical methods, and electrochemical sensors. After theinitial six-week period, seven weeks are devoted to labora-tory exercises. Students are divided into groups of three toanalyze their field samples. The final week is devoted toclassroom presentations.

Airborne particulate matterStudents use all the previously mentioned instruments to an-alyze particulate matter for inorganic and organic compo-nents. They are provided with a laboratory manual that con-tains briefs on particulate matter, sampling procedures forairborne particulate matter, and method summaries for thecollected particulate matter determinations. The major pur-pose is to emphasize in a practical way the complex natureof airborne particulate matter. Relevant ASTM and EPAmethods (9, 10) are noted for each method summary, andstudents are expected to review them carefully. Althoughclass work is emphasized during the first five weeks, studentsalso collect particulate matter samples from the homes ofstudents and friends in their community; loaded filter mem-branes are stored in desiccators for later chemical analysis.Sampling is typically conducted in the living room, with

the collection pump turned on when occupants are aboutto leave for work or school and turned off on their returnhome. It takes about 24 h of sampling time (3−4 days inthis noncontinuous fashion) to adequately load a filter mem-brane with particulate matter. Standard methods or modi-fications of established methods are used to analyze the

Box 3. Content of EMI course

Class topicsClassical versus instrumental methodsEnvironmental sampling: Equipment and methodsExtraction and separation techniquesPrinciples of analytical instrumentationComputer and automationSupercritical fluid extraction and chromatographyElectrochemical sensorsRadiochemical methodsClass projectsSampling plan for environmental projectsLiterature reviewsLaboratory experimentsDetermination of lead in airborne particles by AADetermination of pesticide residue on indoor particulate

by GC-ECDDetermination of VOCs in particulate water by purge and

trap followed by GC/MSDetermination of water-extractable nitrite on indoor

part iculates by HPLC and FT-IR


air borne particulate for lead by flame AA, the pesticideschlordane and aldrin by GC-ECD, water-extractable nitriteby HPLC and FT-IR, and VOCs by GC/MS and purgeand trap. Water-extractable nitrite on indoor particulate matter is

easily determined by HPLC (11). Loaded and blank filtermembranes are cut into four segments. One segment isplaced in a 30-mL Teflon vial with 20.0 mL of reagentwater and shaken for 30 min. After extraction, the solu-tion is syringe-filtered, and a 5.0-mL aliquot is derivatizedwith 2,4-dinitrophenylhydrazine. Blank samples of thewater extract of clean filter membrane are analyzed simul-taneously with standards and samples. The HPLC condi-tions used are those described by Kieber and Seaton (11).Students find concentrations of nitrite in the range0.25−0.45 mM. Although the real significance of this de-termination has not been established, this gives the classan opportunity to discuss the possible sources of airbornenitrite and the possibility that nitrous acid might form onthe surface of airborne particles.A solution of reagent water and particulate matter is

pre pared by adding two or three segments of a filter mem-brane loaded with particulate matter to a 40-mL vial andfilling it with reagent water, leaving no headspace, andplacing it in a sonic vibrator for 15 min. Two minutesafter vibration, the solution is either extracted with 2 mLof pentane, and VOCs are determined according to EPAMethod 505, or a 5.0-mL aliquot is withdrawn for purgeand trap followed by thermal desorption and GC/MS ac-cording to EPA Method 524.2. Compounds extracted

from particulate water by these methods include benzene,toluene, ethylbenzene, 1,2-dichlorobenzene, and naphtha-lene. Although these compounds are not obtained by allgroups, students speculate on the sources of the compoundsidentified during class discussions.

Resource issues Incorporating project-based laboratory activities into anundergraduate analytical chemistry course is a challengebecause there are always limits on physical, financial, andhuman resources. Preparation is essential. For air-monitor-ing projects, pumps and other air-sampling apparatuses areneeded. The instructor must know what projects are feasi-ble given the available laboratory facilities and resources.Pertinent methods of air sampling and analysis should bereviewed, and a list should be created of projects that canbe completed in the required time frame. Projects shouldrequire simple, well-established analysis methods that canbe modified if there are time constraints or if there is aneed to minimize complexities.Research assistants (RΑs)high school, undergraduate,

and graduate studentsfabricate impingers for air-samplingtrains, perform trial runs of modified EPA methods, and,where appropriate, optimize instrumental conditions for spe-cific analyses using analytical equipment. Experiments areconducted to acquire baseline data for future comparisonsand establish the feasibility of conducting similar experimentsfor laboratory projects during a six- to seven-week timeframe. When available, RAs who previously worked on similar projects serve as technical assistants.The instructor has the main responsibility for setting up

the instruments, teaching students to operate them, and in-teracting with the teams. Students often spend more thantheir allotted time in the laboratory, frequently requiringthe instructor and other team members to work long hours.At later stages of the projects, especially during the last twoto three weeks of activities, there can be heavy resource de-mands on available instrumentation, with the AA, GC-ECD,and GC/MS running simultaneously. Assistance from theRAs is helpful during this crucial time.

A course evaluationAnalyzing ambient and indoor air as part of their trainingin undergraduate analytical chemistry courses directs stu-dents’ attention to an important community health con-cern. Although each of us has undoubtedly encounteredthe student whose only mission in the laboratory is to “getit over with,” it is remarkable to see attitude changes as stu -dents move from classical laboratory experiments to smallgroup projects. They are eager to examine the project datapertaining to the homes and express concern about themeaning and accuracy of the values. Students’ interests areheightened when an issue demands sensitivity, such as thereligious use of mercury.

Yvette Samuels prepares tomeasure air sample levels.


Course work is demanding. At the end, somestudents complain that the workload is too heavyfor the number of credits; the measurement and in-strumentation course is now under considerationfor increased credit and laboratory hours. However,some students go beyond the course requirements;they are inquisitive and enthusiastic about researchopportunities and internships. Their work oftenmerits selection for poster presentation at our annu-al Environmental Issues Conference.Enhancing the undergraduate research program is

critical for maintaining and improving project-basedlaboratory exercises. A benefit of this effort is thatdelicate, sophisticated pieces of analytical equipmentare better maintained and more easily incorporatedinto teaching programs when in constant use.If registrants for the QA and EMI courses are

better prepared, then their hands-on training experi-ence will yield higher-quality and more meaningfuldata. So that students can navigate the traditionalpart of the QA laboratory course with greater ease,sections of lower-level chemistry courses should bestreamlined. After completing a year of college-levelchemistry, a significant number of students still seemvery deficient in their knowledge of the simple techniquesrequired for solution chemistry. Underprepared studentsbenefit most from group work, both in class and in the lab-oratory, with well-prepared students serving as mentors.

Support for high school, undergraduate, and graduate students to serve as RAsand for curriculum development was provided by the National Aeronautics andSpace Administration (NASA) Minority University Research and Education Pro-gramNASA Partnership awards NCC5–205, NASA PAIR at CUNY, and NASAMUSPIN grant NCC5-98. Analytical instruments were provided by funds fromthe Brooklyn Borough President’s Office. We also acknowledge the NSF-fundedNew York City−Louis Stokes Alliance for Minority Participation in Science, Engi-neering, and Mathematics and the City University of New York, PSC CUNYgrant 69230-0029.

References(1) Christian, G. D. Anal. Chem. 1995, 67, 532 A.(2) Thorpe, T. M.; Ulman A. H. Anal. Chem. 1996, 68, 477 A.(3) Wenzel, T. J. Anal. Chem. 1995, 67, 790 A.(4) Wenzel, T. J. Anal. Chem. 1998, 70, 470 A.(5) Fitch, A.; Wang, Y.; Mellican, S.; Macha, S. Anal. Chem. 1996, 68, 727 A.(6) Johnson, C. Population and Environment: A Journal of Interdisciplinary

Studies 1999, 20, 443.(7) Christian G. D. Analytical Chemistry; 5th ed.; Wiley & Sons: New York, 1994.(8) U.S. Environmental Protection Agency Method T05-1. In Compendium of

Methods for the Determination of Toxic Organic Compounds in AmbientAir; U.S. Government Printing Office: Washington, DC, April 1984.

(9) Standards D4532, D4185, D4947, D5197. In Annual Book of ASTM Stan-dards; ASTM: Philadelphia, PA, 1997; Section 11, Vol. 11.03.

(10) U.S. Environmental Protection Agency. Compendium of Methods for the

Determination of Air Pollutants in Indoor Air; EPA/600/4-90/010; U.S. Gov-ernment Printing Office: Washington, DC, April 1990.

(11) Kieber, R. J.; Seaton, P. J. Anal. Chem. 1995, 67, 3261−3264 .(12) U.S. Environmental Protection Agency. Air Quality Criteria for Particu-

late Matter; Vol. 1; DC sections. 1.1 to 2.4; Report No. EPA/600/P-95/001aF; U.S. Government Printing Office: Washington, DC, 1996.

(13) U.S. Environmental Protection Agency. National Air Quality and Emis-sions Trends Report; 1995, EPA-454/R-96-005; U.S. Government PrintingOffice: Washington, DC, October 1996; p 25.

(14) New York City Dept. of Environmental Protection. 1998 Annual ReportImplementing Community Right-to-Know Laws in New York City; p 49.

(15) Deckery, D., et al. N. Engl. J. Med. 1993, 329, 1753–1759.(16) Pope, C. A.; Schwas J.; Rangoon, M. R. Ach. Environ. Health 1992, 47,

221–217.(17) Neas, L. M., et al. Am. J. Epidemiol. 1994, 139, 1088–1099.(18) U.S. Environmental Protection Agency. 1989 Exposure Factors Hand-

book.Washington, DC: Office of Health and Environmental Assessment:EPA report no. EPA/600/8-89/043; March 1990, p 3.7.

(19) Harrison, L.; Michalsky, J.; Berndt, J. Appl. Opt. 1994, 33, 5118–5125.

Wilbert W. Hope is an assistant professor at Medgar Evers College.His research interests include using GC/MS for analyzing VOCs in am-bient and indoor air, and he is currently conducting air quality studiesin Brooklyn with undergraduates. Leon P. Johnson is professor ofphysics at Medgar Evers College. He is currently conducting researchwith undergraduates of atmospheric aerosols through ground-basedremote sensing and photometry of variable and binary stars. Addresscorrespondence about this article to Hope, Department of Physical,Environmental, and Computer Sciences, Medgar Evers College, 1150Carroll St., Brooklyn, NY 11225 ([email protected]).

Student Ryan Hutchinson adjusts a flowmeter totest ambient air for total suspendable particles.

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Peer Reviewed: Urban Air: Real Samples for Undergraduate Analytical Chemistry