Response surface optimisation applied to a headspace-solid phase microextraction-gas chromatography-mass spectrometry method for the analysis of volatile organic compounds in water matrices

Abstract

A new method for the simultaneous determination of 12 volatile organic compounds (trans-1,2-dichloroethene, 1,1,1-trichloroethane, benzene, 1,2-dichloroethane, trichloroethene, toluene, 1,1,2-trichloroethane, tetrachloroethene, ethylbenzene, m-, p-, o-xylene) in water samples by headspace solid phase microextraction (HS-SPME)-gas chromatography mass spectrometry (GC-MS) was described, using a 100 mm PDMS (polydimethylsiloxane) coated fibre. The response surface methodology was used to optimise the effect of the extraction time and temperature, as well as the influence of the salt addition in the extraction process. Optimal conditions were extraction time and temperature of 30 min and -20 degrees C, respectively, and NaCl concentration of 4 mol L(-1). The detection limits were in the range of 1.1 x 10(-3)-2.3 mu g L(-1) for the 12 volatile organic compounds (VOCs). Global uncertainties were in the range of 4-68%, when concentrations decrease from 250 mu g L(-1) down to the limits of quantification. The method proved adequate to detect VOCs in six river samples.