Measurement of volatile organic compounds by the US Environmental Protection Agency Compendium Method TO-17. Evaluation of performance criteria

Abstract

An evaluation of performance criteria for US Environmental Protection Agency Compendium Method TO-17 for monitoring volatile organic compounds (VOCs) in air has been accomplished. The method is a solid adsorbent-based sampling and analytical procedure including performance criteria for four merit parameters. These are: (1) the method detection limit (MDL); (2) the method precision; (3) the agreement between two samples taken at different flow-rates over the same time period [a distributed volume pair (DVP)]; and (4) audit accuracy. A two-adsorbent tube packing of Carbotrap and Carboxen 1000 (Supelco) was tested. Synthetic mixtures containing 41 compounds at concentrations of 10 ppb (v/v) or 2 ppb (v/v) each in humidified zero air, and indoor air from a personal residence, were sampled for 1-h periods during which 1-l and 4-l samples were obtained simultaneously. For synthetic samples, the MDL was determined to be < or = 0.5 ppb (v/v) for 29 of the 41 compounds examined for samples at 47% relative humidity (RH), and for 27 of 41 compounds at 85% RH. The method precision at both 2 and 10 ppb (v/v) was < or = 20% for 90+ % of the samples using five sampling runs and the DVP samples were within 25% for 80% of the samples. For the indoor samples, 26 target compounds were tentatively identified and 12 unknowns were detected; all but 10% of these compounds met the DVP criteria.