Determination of volatile organic compounds in air using a dehumidified and ventilated diffusive sampler, thermal desorption and gas chromatography with flame ionization detection

Abstract

A portable dehumidified and ventilated diffusive sampler (DVDS) incorporating three diffusive tubes and a domestic battery-driven fan dryer was developed to solve the problems of high humidity and stagnant air for environmental monitoring of volatile organic compounds (VOCs). Using Tenax GR as adsorbent, thermal desorption and cryogenic on-column focusing prior to capillary GC analysis with flame ionization detection, the 10 most common aromatic and halogenated VOCs were determined with the DVDS, giving linear working ranges 3.2 μg m-3-770 mg m-3 for 1 h sampling, sampling rates of 0.64-0.98 ml h-1 and RSD of 4-6%. The good repeatability is due to the use of a small-diameter diffusive tube (0.32 mm id) and reproducible ventilation in the DVDS. The optimized analytical parameters are temperature 10-40°C, relative humidity 0-100%, sampling time 15-480 min and storage for up to 21 days. Quality assurance procedures were developed for the calibration and preparation of the DVDS. The reliability of the method was established by parallel determinations at a given field station using both the DVDS and the active sampling method.