Determination of naphthalenesulfonate isomers in industrial effluents and river water by solid-phase extraction and capillary zone electrophoresis

This work presents a method to separate polar naphthalenesulfonate (NS) isomers by capillary zone electrophoresis (CZE) with ultraviolet detection in industrial effluents and river water samples. The method involves extraction of samples by a polystyrene-divinylbenzene copolymer (PS-DVB) solid-phase extraction (SPE) cartridge. The most effective CZE separation conditions were obtained in 20 mM borate buffer with 30% acetonitrile at pH 9.0 and 30 °C. The method proposed herein provides a high precision and sensitivity for NS isomers, to quantitation at ≤ 1.0 μg/L in 200 mL of the water samples. Recovery of the NS isomers in spiked water samples ranged from 73% to 87% while RSD ranging from 5.6 to 9.7%. The analysis of industrial effluents and river water samples was performed and naphthalene-2-sulfonate was found as a major pollutant. The difficulties in quantitating and identifying analytes in complex environmental samples can be resolved by using an internal standard response factor to calculate concentrations and relative migration times for peak confirmation.