DETERMINATION OF ALKYL SULFATES AND ALKYL ETHOXYSULFATES IN WASTE-WATER TREATMENT-PLANT INFLUENTS AND EFFLUENTS AND IN RIVER WATER USING LIQUID CHROMATOGRAPHY/ION SPRAY MASS-SPECTROMETRY

A method has been developed for monitoring concentrations of alkyl sulfates and alkyl ethoxysulfates (AES) in environmental matrices using ion spray LC/MS to determine individual AES species. The ion spray LC/MS technique enables interference-free quantitation of completely resolved (by alkyl and ethoxylate chain length) AES species at less than part-per-billion concentrations. This method was validated using spike and recovery and measuring concentrations of 36 AES species (ranging in size from 12 to 15 alkyl carbons and from 0 to 8 ethoxylate groups) in river water and influents and effluents from a municipally owned wastewater treatment plant. Two different spike concentrations were used for each matrix, and the total mass of AES recovered from each matrix was greater than or equal to 90% of the amount spiked, except for effluent at a high spike level, from which 75% was recovered. A mathematical model, which fits experimentally measured concentrations to an expected distribution of AES components, enables prediction of total AES concentrations from measurements of a few selected components in cases where expected distributions are known with sufficient accuracy.