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

Secondary alkane sulfonate (SAS) surfactants were determined in aqueou s samples from sewage treatment plants using solid-phase extraction (S PE) and a single-step procedure that combines elution and injection-po rt derivatization for sample analysis using gas chromatography/mass sp ectrometry (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 wa s effectively recovered from samples of raw sewage (>92%) and from pri mary (>98%) and secondary (>85%) sewage effluents. No sample cleanup s teps were necessary because the identification and quantitation of SAS isomers and homologs were performed using mass selective detection. T he overall precision of the method, indicated by the relative deviatio n, for SAS in raw sewage, primary effluent, and secondary effluents wa s 7.1, 5.2, and 10.4 %, respectively. The concentration of SAS in muni cipal 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) conc entrations also were determined in wastewater samples.