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ENHANCED CONCENTRATION AND ANALYSIS METHOD FOR MEASURING WATER SOLUABLE ENDOGENOUS COMPOUNDS IN HUMAN BREATH
Citation:
Pleil, J D., M Colon, AND A B. Lindstrom. ENHANCED CONCENTRATION AND ANALYSIS METHOD FOR MEASURING WATER SOLUABLE ENDOGENOUS COMPOUNDS IN HUMAN BREATH. Presented at American Chemical Society 221st National Meeting, San Diego, CA, April 1-5, 2001.
Impact/Purpose:
The objective of this task is to develop state-of-the-art methods for measuring xenobiotic compounds, to include the isolation of the analyte from the appropriate matrix (extraction), preconcentration (typically sorbent-based), and analysis via GC/MS and/or LC/MS. Once established, these methods will be applied in small scale pilot studies or demonstration projects. Particular emphasis will be placed on methods which are readily transferable to other laboratories, including those within the Human Exposure and Atmospheric Sciences Division (HEASD), the National Exposure Research Laboratory (NERL), other EPA Laboratories, Program Offices, Regions, and academic institutions.
Specific objectives of this task include the following:
1) Development of GC/MS and LC/MS methods for the measurement of key xenobiotic compounds and their metabolites (to include the pyrethroid pesticides, perfluorinated organic compounds, and the BFRs) in relevant environmental and biological matrices.
2) Development of efficient low cost methods for the extraction and clean up of these compounds collected from relevant matrices.
3) Determination of xenobiotic compound and metabolite concentrations in samples derived from laboratory and field monitoring studies to help assess exposures and evaluate associated risks.
Description:
Exhaled human breath analysis has become a standard technique for assessing exposure to exogenous volatile organic compounds (VOCs) such as trihalomethanes from water chlorination; aromatics, hydrocarbons, and oxygenates from fuels usage; and various chlorinated solvents from industrial or consumer exposures. The time dependent breath concentration changes during exposure (uptake) and post-exposure (eliminations) periods have been employed to estimate biological parameters such as blood levels, compartmental residence times, tissue capacities, peak exposure, minimum total does, and metabolic clearance rates. In recent studies of fuels and solvent exposures, breath measurement has become a non-invasive surrogate for blood measurements.
The success of using breath as a "biological fluid" has created interest in measuring additional compounds that may serve as internally produced biomarkers of external chemical exposures which could serve as a simple, non-invasive exposure assessment tool for internal dose. Such biomarkers will most likely occur at very low concentrations compared to the exposure and will be very water soluble; these are two properties that make gas phase analysis difficult. We have developed a sampling and analytical method that accentuates the water soluble fraction of organic compounds in breath for GC/MS analysis. Multiple breaths are passed through special glassware at subambient temperature (-80 C); upon heating to 37 C, the condensed water is sparged with dry nitrogen into a standard 1-liter volume breath sampling container (SUMMA canister) also at -80 C. When warmed to room temperature, the canister becomes positively pressurized and is then analyzed as a normal single breath sample, yet contains an elevated amount of the polar volatile organic compounds as trapped from 40 or 50 breaths. This allows more detailed analysis of the normally occurring metabolic products as well as putative biomarkers of exposure in breath.
To date, we have identified a variety of compounds in normal (healthy) adults that include C3 to C9 n-aldehydes, C3 and C4 branched aldehydes, alcohols, terpenoids, ethers, acetates, etc. have been tentatively identified and work continues to unambiguously confirm as many compounds as possible. In the long run, we anticipate using pattern of endogenously produced compounds expressed in breath as an indicator of external exposure.
This work has been reviewed in accordance with the U.S. Environmental Protection Agency's peer and administrative review process and approved for presentation and publication. Mention of trade names or commercial products does not constitute endorsement or recommendation for use.