Determination of linear alkylbenzenesulfonates in wastewater treatment plants and coastal waters by automated solid-phase extraction followed by capillary electrophoresis-UV detection and confirmation by capillary electrophoresis-mass spectrometry

Linear alkylbenzenesulfonates (LASs) were determined in wastewaters and coa stal waters by solid-phase extraction, using two different sample preparati on protocols depending on the sample treated, followed by capillary electro phoresis and ultraviolet detection (CE-UV). The linear range of the propose d method varied from 3 to 53 and from 25 to 495 mu g/l, depending on the co mpound, with a limit of detection of 1 mu g/l when 250 ml of coastal water was preconcentrated. [M-H](-) ions were used for CE-MS confirmation after q uantification by CE-UV. CE-MS diagnostic ions were the same ones used in LC -electrospray (ESI) MS and corresponded to m/z 297, 311, 325 and 339 for C- 10, C-11, C-12 and C-13 LASs, respectively. LASs were determined in wastewa ter samples of the influent and effluent of three wastewater treatment plan ts (WWTPs), two of them using biological treatment with secondary settlemen t and receiving mainly domestic wastewaters whereas one of the plants was o perated with physicochemical treatment and received mainly industrial waste waters. LASs were also analyzed in two samples from coastal waters of the b ay of Cadiz (Spain) receiving untreated domestic effluents. All samples wer e also analyzed by LC-ESI-MS and the results are compared with the CE-W met hod developed in this work The concentration levels of total LASs varied fr om 988 to 1309 mu g/l in the influents of WWTPs, whereas in the effluents t he concentrations varied from 136 to 197 mu g/l. The levels of LASs in coas tal wastewaters of the bay of Cadiz varied from 739 to 911 mu g/l, indicati ng that the wastewaters discharged into the bay did not undergo any treatme nt at all. (C) 2000 Elsevier Science B.V. All rights reserved.