References

Andersson, K. et al., 1997: TVOC and Health in Non-industrial Indoor Environments. Indoor Air, 7, 78-91.Apel, E. C. et al., 2003: A fast-GC/MS system to measure C2 to C4 carbonyls and methanol aboard aircraft. J. Geophys. Res., 108, 8794-8806.Atkinson, R., 2000: Atmospheric chemistry of VOCs and NOx. Atmos. Environ., 34, 2063-2101.Devlin, R. B. et al., 1997: Health effects of ozone. Sci. Med., 8-17.Kelly, T. J. and M. W. Holdren, 1995: Applicability of canisters for sample storage in the determination of hazardous air pollutants. Atmos. Environ., 29, 2595-2608.

Introduction

Chemistry• Both anthropogenic and natural sources emit VOCs into the urban atmosphere• VOCs react with either nitrite radicals at night or hydroxyl radicals during the day to produce reactive organic peroxy molecules• Increased peroxy molecules result in increased production of ozone (Atkinson, 2000)

• During the evening, NOx chemistry becomes the driver (Warneke et al., 2004) NO + O3 NO2 + O2

NO2 + O3 NO3 + O2

NO2 + NO3 ↔ N2O5

OH + NO HONO OH + NO2 HNO3

• Early morning photolysis of HONO results in rapid increase in OH, jumpstarting urban photochemisty

Health• VOCs have direct adverse affects on human health (Andersson et al., 1997)

• Production of O3 by VOCs reaction processes (Devlin et al., 1997)

Regulation• 1990 Clean Air Act Amendments list 188 VOCs as hazardous air pollutants• Currently monitored via Compendium Method TO-15

24-hour collection of ambient samples in SUMA canisters Analysis of samples at centralized testing facilities Problem: Some VOCs have appreciable degradation during storage (Kelly and Holdren,

1995)

Application of Extractive Fourier Transform Infrared Spectroscopy with Cryogenic Preconcentration: Laboratory Results and Applications

Patrick I. Buckley1, David A. Bowdle2, Michael J. Newchurch1

1Univ. of Alabama in Huntsville, 2Earth System Science Center - Retired

Contact info: Patrick I. Buckley buckley@nsstc.uah.eduNOAA ESRL Global Monitoring Annual Conference, 18 May 2010, Boulder, CO

ECIP-FTIR Methodology

ECIP-FTIR Objectives

11

batchii iVOC cell VOCamb VOCi

amb trap trap cell amb

AF V FC C

F F t L F

1 1

1

contii iVOC amb VOCamb VOCi

dil celltot cell amb

AF F FC C

F F L F

VOCdiltrapbypasstraptrapEBCcellamb FFFFFFFF 21

Batch Sampling – Four-hour preconcentration at 2 LPM; Detection Limits > 10 pptv

Continuous Sampling – 15-minute resolution at 2 LPM; Detection Limits > 10 ppbv

Volumetric Flow Rate

Figure 3: The ECIP-FTIR Instrument Layout. Panel A shows the entire instrument layout. From left to right, the FTIR, cryocooler, and electronics compartment with operations PC can be seen. Panel B shows the fluid subsystem including flow passages, inlet pumps, and shut off and flow selection valves. Panel C shows the optical subsystem with emphasis on the FTIR and gas cell. Panel D show the cryogenic subsystem and QA/QC manifold along with mass flow controllers (green boxes). Panel E shows the data acquisition system and mass flow junction boxes.

Figure 1: NOx/O3 schematic In the presence of VOCs (From Atkinson, 2000)

Table 1: Comparison of key specifications from Apel et al. (2003) Fast GC/MS system, EPA Method TO-15 (1997), and the ECIP-FTIR

Flow Diagram

Figure 4: The ECIP-FTIR Flow Schematic. Red highlight Continuous Flow Green highlight Batch Sampling Purple highlight QA/QC

Target Compounds

Table 2: Average concentrations are from data collected between May 2005 and May 2006 in Birmingham, AL using EPA Method TO-15. (Data courtesy of R. Dillard, Jefferson County Department of Health, Birmingham, AL)

Target Analyte Molecular Weight (g/mol) Average (ppbv)Formaldehyde 30.03 3.100Acetaldehyde 44.05 1.0351,3-butadiene 54.09 0.100Acrolein 56.06 0.725Carbonyl sulfide 60.07 N/DVinyl chloride 62.50 N/DBenzene 78.11 0.850Methylene chloride 84.93 0.092Chloroform 119.38 0.035Trichloroethylene 131.39 N/DCarbon tetrachloride 153.82 0.114Tetrachloroethylene 165.80 0.052

Performance

Figure 2: ECIP-FTIR RMS signal to noise (SNR) vs. sample time (1024 scans = 60 minutes).

Laboratory Results

Cryogenic Performance

• During routine operations, the ECIP-FTIR preconcentrates batch samples within the cryotrap. The typical cooling cycle reduces the temperature of the cryotrap to 100 K (-173 °C). Heater coils maintain this temperature remotely. At present, the ECIP-FTIR cryogenic system is capable of reaching a range of temperatures.

• Laboratory spectra illustrate the ECIP-FTIR has

Adequate spectral resolution to identify trace pollutants in laboratory air

Good instrument sensitivity

The capability to quantify multiple compounds in complex calibration and in-air mixtures

Figure 5: Cryocoolerefficiency. The blacktrace is the coldheadtemperature. The blue and red traces are trap temperatures at two differentpositions along the stack.

Figure 6: Laboratory spectrum of methanol inAir. The blue trace is the measured spectrum. Thegreen trace is a deconvolved high-resolutionlibrary spectrum.

Birmingham Field Study

Coke Plant

U.S. Pipe

Smelter

• Through a collaboration with the Jefferson County Department of Health and Atmospheric Research and Analysis, the ECIP-FTIR will be deployed in North Birmingham (yellow box) October 2010 – March 2011.

• This site is in close proximity to several industrial facilities, which frequently affect the air quality at the North Birmingham site.

• Also in close proximity are North Birmingham Elementary and Lewis Elementary (green stars), illustrating the importance of air quality measurements in this area.

N. BHM VOC Data

02468

10

pp

bv

Acetaldehyde 1,3-Butadiene Benzene Formaldehyde

Figure G: VOC data from N. Birmingham site collected from July 2005 – June 2006. Analysis followedEPA TO-15 GC/MS protocol.

• Improve temporal coverage Continuous operation vs. 1 in 6

• Improve temporal resolution 4-hour batch, 15-minute cont. flow

• Improve data latency Near-real-time products

• Improve chemical specificity One analyzer for all IR-active gases

• Improve user interaction Mobile, autonomous, non-specialist

• Reduce life cycle costs Low annual, comparable start up

• Maintain or improve data quality Meet EPA detection limits, on-board QA/QC

• Maintain or improve traceability Innovation while using EPA-approved chemistry and physics

• Presence of carbonyls Source of hydroxyl radical

• Presence of aromatics Reacting with hydroxyl leading to O3

formation

• Presence of chlorinated compounds such as carbon tetracholoride (not shown) Enhancement of VOC oxidation and HCl formation

• NOx and O3 data from N. Birmingham along with ECIP-FTIR VOCs will provide valuable information about VOC sources, sinks, and processes