QUANTITATIVE-ANALYSIS OF ALKYLBENZENESULFONATE SURFACTANTS USING CONTINUOUS-FLOW FAST-ATOM-BOMBARDMENT SPECTROMETRY

A quantitative method for the analysis of linear alkyibenzenesulfonates (LAS) has been developed using continuous-flow fast atom bombardment and tandem mass spectrometry. Simultaneous analysis is of all LAS homologues is possible by scanning the parent ions of m/z 183, which is a product ion common to all LAS subjected to collisionally induced dissociation. Similarly, branched alkylbenzenesulfonates (ABS) can be analyzed by scanning the parent ions of m/z 197. Samples were concentrated using solid-phase extraction on C18 disks. Because separation Is not required, samples can be analyzed in 4 min or less using flow injection analysis. Quantitation is linear from 1 to al least 100 ng; the detection limit is 1 ng injected, corresponding to 0.5-mu-g/L in 1-L water samples. This method has been used to determine LAS concentrations in samples taken from a waste water treatment plant and in river water. In this activated sludge treatment plant, removal of LAS from waste water occurred by adsorption to sludge as well as by biodegradation. Relative concentrations of longer chain homologues in sludge were higher than in the plant influent, Indicating that these homologues accumulate on sludge. LAS adsorbed to sludge were eventually degraded in the plant's aerobic sludge digester.