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OPTIMIZING THE PAKS METHOD FOR MEASURING AIRBORNE ACROLEIN
Citation:
Herrington, J., L. Zhang, D A. Whitaker, L S. Sheldon, AND J. Zhang. OPTIMIZING THE PAKS METHOD FOR MEASURING AIRBORNE ACROLEIN. Presented at International Society of Exposure Analysis, Stresa, Italy, September 21-25, 2003.
Impact/Purpose:
The overall goal of human exposure research in air toxics is to develop the methods, data, and models of exposure that will provide the scientific basis for EPA to move to a risk-based program and that will enhance NATA. Specific objectives for this measurement task are to:
o Characterize exposure concentrations and variability in critical microenvironments using targeted measurement studies;
o Quantify the relationship of personal exposure to ambient and indoor concentrations;
o Identify critical microenvironments, human activities, and factors influencing exposure to air toxics;
o Develop methods to quantify exposure from background, point or area sources, and microenvironmental sources;
o Evaluate aggregate and cumulative exposures.
Description:
Airborne acrolein is produced from the combustion of fuel and tobacco and is of concern due to its potential for respiratory tract irritation and other adverse health effects. DNPH active-sampling is a method widely used for sampling airborne aldehydes and ketones (carbonyls); however, based on our tests it is not suitable for sampling acrolein, because of its low collection efficiency (20%) and poor stability. The Passive Aldehydes and Ketones Sampler (PAKS) is a diffusive, tube-type sampler, which utilizes a dansylhydrazine (DNSH)-coated silica-based bonded C18 sorbent to collect airborne carbonyls. Carbonyls react with DNSH to form their corresponding derivatives that are retained on the sorbent. The derivatives are subsequently extracted and quantified using an HPLC-fluorescence technique. The PAKS method has a collection efficiency of >60% and an improved DNSH-derivative stability for acrolein compared to DNPH-derivative stability. However, it is still desirable to increase the PAKS acrolein collection efficiency and derivative stability. The addition of pH buffers (citric acid/sodium citrate), a polymerization inhibitor (hydroquinone), and an alternative hygroscopic agent (1,3-butanediol) to the derivatization solution, are being evaluated for their effectiveness in improving acrolein collection efficiency and stability on the collection medium (C18 sorbent). The evaluation is being conducted subsequent to 24 - 48 hours of exposure and after 0, 1, 2, 4, 7, and 11 days of storage at 4oC. The coating solution containing optimal amounts of buffer solution, hydroquinone, and 1,3-butanediol will be determined after a variety of tests. Preliminary results indicate that the PAKS acrolein collection efficiency and stability can be improved with a combination of the optimal parameters mentioned above.
This work has been funded wholly or in part by the US EPA under PO#2D-5806-NAEX . It has been subjected to Agency review and approved for publication.