Extraction and HPLC analysis of benzene and toluene in water.

Abstract

Groundwater pollution with petroleum hydrocarbons is a widespread problem. Two of the most toxic and soluble are benzene and toluene. Their volatility also makes accurate analysis difficult by the commonly used gas chromatography method. In this study, reverse phase high performance liquid chromatography was evaluated for determination of their concentrations in mixtures simulating contamination ground water. The contaminants, in concentrations of 2-5 mg/L, were first extracted from the water by siphoning it through 15 cm³ of Altech XAD-4 resin contained in a buret. The resin was found to remove 99% of the contaminants. Various rinse agents, combinations of rinses, and techniques were tested and compared to determine the most efficient way to recover the benzene and toluene from the resin. The highest recoveries, 50%, and most reproducible results were obtained by using 90mL of HPLC grade methanol in a series of 10mL elutions through the resin. A rinse with methylene chloride followed by 6-10 rinses with methanol was found to be a satisfactory method of cleaning the resin.