Analysis of linear alkylbenzenesulfonates in water samples by large-volume injection-port derivatization and gas chromatography-mass spectrometry.

This work presents a modified method to analyze linear alkylbenzenesulfonates (LASs) in water samples. The method involves extraction of samples by a graphitized carbon black (GCB) cartridge, and direct derivatization in the GC injection port using a large-volume (10-20 microl) direct sample introduction (DSI) device with tetraalkylammonium (TAA) salts. The analytes were then identified and quantitated by ion-trap GC-MS. The large-volume DSI injection-port derivatization technique provides sensitivity, fast and reproducible results for LAS residues, to quantitation at 0.1 microg/l in 200 ml of water samples. The retention effect of TAA salts in the injection port was not detected. Enhanced selected mass chromatograms of [M-55]+ ions of butylated C10-C13 LASs by electron impact ionization MS allows one to determine LAS residues at trace levels in environmental samples. Recovery of total LASs in spiked variety water samples ranged from 89 to 112% while RSDs ranged from 2 to 13%.