Multivariate optimization of a solid phase microextraction-headspace procedure for the determination of benzene, toluene, ethylbenzene and xylenes in effluent samples from a waste treatment plant

A method based on solid-phase microextraction (SPME) and gas chromatography with flame ionization detection (GC-FID) has been optimized for the determination of benzene, toluene, ethylbenzene and xylenes (BTEX) in water released front a waste treatment plant. The extraction step was optimized using fractional factorial and central composite designs including the following experimental factors: saline concentration; extraction time; desorption time; agitation velocity; headspace volume. A multiple function was used to describe the experimental conditions for simultaneous extraction of the compounds. The procedure, based on direct SPME at 50 degrees C, using a polydimethylsiloxane fiber, showed good linearity (r > 0.997 over a concentration range 2-200 mu g L-1) and repeatability (relative standard deviation (RSD) < 4.23% for all compounds from 0.14 to 0.84 mu g L-1. Concentrations of the target compounds in these samples were between 145.8 and 1891 mu g L-1. (C) Elsevier B.V. All rights reserved.