DETERMINATION OF BENZENESULFONATES AND NAPHTHALENESULFONATES IN WASTE-WATER BY SOLID-PHASE EXTRACTION WITH GRAPHITIZED CARBON-BLACK AND ION-PAIR LIQUID-CHROMATOGRAPHY WITH UV DETECTION

Highly water-soluble benzene- and naphthalenesulfonates are widely use d in chemical, pharmaceutical, and textile industries, This paper pres ents a solid-phase extraction method for the enrichment of aromatic su lfonates from industrial wastewaters. A graphitized carbon black (Carb opack B) with positively charged oxonium groups was used as an adsorbe nt. The graphite structure and anion exchange sites make Carbopack B a very selective adsorbent for aromatic anions. Desorption of sulfonate s was achieved with 50 mM ammonium acetate in methanol/ dichloromethan e. Reversed-phase ion-pair liquid chromatography with diode array dete ction was used for separation and quantification. With the exception o f some amino-substituted compounds, recoveries were generally >90% wit h relative standard deviations of 0.2-5.0% for replicate analyses. The detection limits for 100 mL samples were between 0.1 and 1.0 mu g/L. Higher molecular compounds, especially humic substances, were almost a bsent in the final extracts, which is helpful for analyses of environm ental samples. Twelve aromatic sulfonates were identified and quantita tively determined by applying this method to wastewater from a textile manufacturing plant. 3-Nitrobenzenesulfonate was found as a major pol lutant in concentrations of up to 5 mg/L.