Determination of linear alkylbenzenesulfonates and their degradation products in water samples by gas chromatography with ion-trap mass spectrometry

A method was developed for the analysis of linear alkylbenzenesulfonates (LAS) and their degradation products, sulfophenylcarboxylic acids (SPC), in samples of sewage effluent and river water. This method involved extraction of the samples by graphitized carbon black cartridge, esterification by a two-step thionyl chloride-trifluoroethanol derivatization procedure, and separation, identification and quantitation by ion-trap GC-MS with EI and low pressure CI modes. High selectivity with few signals was observed in the low pressure CI mass spectra of LAS and SPC. Enhanced sensitivity with protonated molecular ion chromatograms of homologous C₁₀-C₁₃ LAS by CI-MS permit the determination of LAS and SPC at trace concentrations in environmental samples. Recovery rates of LAS and SPC in spiked water samples ranged from 75 to 112% with R.S.D. values from 3 to 26%. The limit of quantitation for both LAS and SPC was estimated to be 0.01 μg/l in 100 ml of water sample. Copyright (C) 1998 Elsevier Science B.V.