Determination of volatile organic compounds in river water by solid phase extraction and gas chromatography

A simple, rapid, and reproducible method is described employing solid-phase extraction (SPE) using dichloromethane followed by gas chromatography (GG) with flame ionization detection (FID) for determination of volatile organic compound(VOC) from the Buriganga River water of Bangladesh. The method was applied to detect the benzene, toluene, ethylbenzene, xylene and cumene(BTEXC) in the sample collected from the surface or 15 cm depth of water. Two-hundred ml of n-hexane-pretreated and filtered water samples were applied directly to a C₁₈ SPE column. BTEXC were extracted with dichloromethane and average concentrations were obtained as 0.104 to 0.372 μg/ml. The highest concentration of benzene was found as 0.372 μg/ml with a relative standard deviation (RSD) of 6.2% , and cumene was not detected. Factors influencing SPE e. g., adsorbent types, sample load volume, eluting solvent, headspace and temperatures, were investigated. A cartridge containing a C₁₈ adsorbent and using dichloromethane gave better performance for extraction of BTEXC from water. Average recoveries exceeding 90% could be achieved for cumene at 4°C with a 2.7% RSD.