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24-HOUR DIFFUSIVE SAMPLING OF TOXIC VOCS IN AIR ONTO CARBOPACK X SOLID ADSORBENT FOLLOWED BY THERMAL DESORPTION/GC/MS ANALYSIS - LABORATORY STUDIES
Citation:
MCCLENNY, W. A., K. OLIVER, H. JACUMIN, H. DAUGHTREY, AND D. A. WHITAKER. 24-HOUR DIFFUSIVE SAMPLING OF TOXIC VOCS IN AIR ONTO CARBOPACK X SOLID ADSORBENT FOLLOWED BY THERMAL DESORPTION/GC/MS ANALYSIS - LABORATORY STUDIES. JOURNAL OF ENVIRONMENTAL MONITORING. Royal Society of Chemistry, Cambridge, Uk, 7:248-256, (2005).
Impact/Purpose:
Develop innovative and customized new measurement approaches for air toxic VOCs as requested by methods development clients.
Description:
Diffusive sampling of a mixture of 42 volatile organic compounds (VOCs) in humidified, purified air onto the solid adsorbent Carbopack X was evaluated under controlled laboratory conditions. The evaluation included variations in sample air temperature, relative humidity, and ozone concentration. Linearity of samples with loading was examined, both for a constant concentration with time varied up to 24 hours, and for different concentrations over 24 hours. Reverse diffusion and its increase with accumulation of sample were determined for all compounds. Tubes were examined for blank levels, for change of blanks with storage time, and for variability of blanks. Method detection levels were determined based on seven replicate samples. After the laboratory evaluation 27 VOCs were selected for quantitative monitoring in the concentration range from approximately 0.1 to 4 ppbv. Comparison of analytical results for active and diffusive samples taken over 24 hours under the same simulated ambient conditions at a constant 2 ppbv were interpreted to estimate the effective diffusive sampling rates (ml min-1) and their uncertainty, and to calculate the corresponding diffusive uptake rates (ng ppmv-1min-1). Many of the rates are reported for the first time.
The United States Environmental Protection Agency through its Office of Research and Development partially funded and collaborated in the research described here under contract 68-D-00-206 to ManTech Environmental Technology, Inc. It has been subjected to Agency review and approved for publication.