Determination of alkylbenzenesulfonates in recent sediments by gas chromatography mass spectrometry

Alkylbenzenesulfonates together with soap are the most widely used anionic surfactants, Linear alkylbenzenesulfonates (LAS) were introduced in the mid-1960s as substitutes for the poorly biodegradable tetrapropylene-benzenesulfonates (TPS). A method is presented for the selective and quantitative determination of IAS and TPS in recent sediments, Alkylbenzenesulfonates were extracted from sediments using methanol. The methanolic extract was passed through a strong anionic exchange column. The alkylbenzenesulfonates contained in the acidic eluate were then derivatized to their corresponding trifluoroethyl esters and quantitatively determined by gas chromatography/mass spectrometry using positive chemical ionization. Limits of quantitation for 10 g sediment samples varied between 1.5 and 21 mu g/kg of dry sediment for single LAS isomers and between 71 and 220 mu g/kg for total LAS. Limits of quantitation for the total of TPS were at similar to 200 mu g/kg. Relative standard deviations of replicate analyses typically ranged from 5 to 10%. Recovery rates of IAS in spiked sediment samples ranged from 79 to 113%. The presented method was applied to surface and subsurface sediments also containing longchain (C-14-C-16)-LAS and mixtures of LAS and TPS.