Analytical Sciences

Determination of Benzene, Toluene, Ethylbenzene and Xylene in River Water by Solid-Phase Extraction and Gas Chromatography

Mohammad A. MOTTALEB,*  Mohammad Z. ABEDIN,** and Mohammad S. ISLAM**

*Department of Chemistry, University of Rajshahi, Rajshahi 6205, Bangladesh
**Department of Chemical Technology and Polymer Sciences, Shahjalal University of Science and Technology, Sylhet 3114, Bangladesh

A rapid and reproducible method is described that employs solid-phase extraction (SPE) using dichloromethane, followed by gas chromatography (GC) with flame ionization detection for the determination of benzene, toluene, ethylbenzene, xylene and cumene (BTEXC) from Buriganga River water of Bangladesh. The method was applied to detect BTEXC in a sample collected from the surface, or 5 cm depth of water. Two-hundred milliliters of n-hexane-pretreated and filtered water samples were applied directly to a C₁₈ SPE column. BTEXC were extracted with dichloromethane and the BTEX concentrations were obtained to be 0.1 to 0.37 µg ml^-1. The highest concentration of benzene was found as 0.37 µg ml^-1 with a relative standard deviation (RSD) of 6.2%; cumene was not detected. The 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 a better performance for the extraction of BTEXC from water. Average recoveries exceeding 90% could be achieved for cumene at 4°C with a 2.7% RSD.

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