DETERMINATION OF SECONDARY ALKANE SULFONATES IN SEWAGE WASTEWATERS BY SOLID-PHASE EXTRACTION AND INJECTION-PORT DERIVATIZATION GAS-CHROMATOGRAPHY MASS-SPECTROMETRY

Secondary alkane sulfonate (SAS) surfactants were determined in aqueous samples from sewage treatment plants using solid-phase extraction (SPE) and a single-step procedure that combines elution and injection-port derivatization for sample analysis using gas chromatography/mass spectrometry (GC/MS). A tetrabutylammonium ion pair reagent was applied both to elute SAS from C,8 bonded-silica disks as their ion pairs and to derivatize SAS ion pairs under GC injection-port conditions. SAS was effectively recovered from samples of raw sewage (>92%) and from primary (>98%) and secondary (>85%) sewage effluents. No sample cleanup steps were necessary because the identification and quantitation of SAS isomers and homologs were performed using mass selective detection. The overall precision of the method, indicated by the relative deviation, for SAS in raw sewage, primary effluent, and secondary effluents was 7.1, 5.2, and 10.4 %, respectively. The concentration of SAS in municipal wastewaters ranged from 0.69 to 0.98 mg/L in raw sewage, from 0.54 to 0.89 mg/L in primary effluents, and from below detection to 0.02 mg/L in secondary effluents. Linear alkylbenzene sulfonate (LAS) concentrations also were determined in wastewater samples.