Chemical removal of humic substances interfering with the on-line solid-phase extraction - Liquid chromatographic determination of polar water pollutants

Different methods for removing interference by humic substances in the anal ysis of polar pollutants have been compared in the analysis of environmenta l water by solid-phase extraction (SPE) with a chemically modified polymeri c resin coupled on-line to liquid chromatography with UV detection. The methods were based on the use of chemical reagents The best method was found to be addition of sodium sulphite to humic-containing water before SP E. The appropriate amount of sulphite depends on the amount of humic substa nces dissolved in the sample for analysis of 50 mt tap and Ebro river water , respectively, 250 mu L and 500 mu L 10% Na2SO3 solution had to be added. In both cases, the recovery values after chemical treatment were similar to those when a Milli-Q-quality water standard was analysed.