Cost effective passive sampling device for volatile organic compounds monitoring

A laboratory-built passive sampler was developed as a simple and cost effective device for monitoring volatile organic compounds (VOCs) such as benzene, toluene and xylene (BTX). Common glass bottles (screw cap, 10 ml, 67.6×10.6 mm ID), packed with 75 mg of activated Tenax TA, were used as passive samplers. After exposed to real sample, the adsorbent was desorbed using a laboratory-built thermal desorption device. The analytes were purged to fill a sampling loop and then injected by a gas sampling valve to a gas chromatograph with a flame ionization detector (FID). All parameters, i.e., desorption time, purge flow rate, gas chromatograph conditions were optimized to obtain high sensitivity, resolution and short analysis time. The system was calibrated by BTX standard gas and the linear regression coefficient of greater than 0.99 was obtained with detection limits 0.3, 0.2 and 0.7 μg m−3 for benzene, toluene and xylene, respectively. The proposed method was implemented for the monitoring of BTX at 10 gasoline stations in Hat Yai, Thailand. The concentrations were found in the range of N.D.–19, 12–200 and 23–200 μg m−3 for benzene, toluene and xylene, respectively.