AUTOMATED DETERMINATION OF LINEAR ALKYLBENZENE SULPHONATE (LAS) IN WASTEWATER TREATMENT PLANTS EFFLUENTS USING ON LINE SOLID-PHASE EXTRACTION FOLLOWED BY HPLC WITH FLUORESCENCE DETECTION

An on line SPE (solid-phase extraction) method followed by HPLC with fluorescence detection has been developed and validated for determining the LAS in inlet and outlet effluents of wastewaters treatment plants. Filtered effluent samples were on line concentrated on a small polymeric reversed phase column, then the trapped LAS are separated on a specialty polar-embedded reversed-phase column and detected by a fluorimeter. The on line SPE method with fluorescence detection showed very good repeatability (from 1.5 to 11.7% depending on the sample loading volume) and robustness with detection limits of 1.5 jug l(-1) for total C(10-13) LAS loading a 5 ml sample volume. This automated method is a cost-effective way to determine LAS also in routine monitoring of inlets and outlets of wastewater treatment plants allowing to optimize treatment procedures.