Liquid chromatographic determination of chloramine-T and its primary degradation product, p-toluenesulfonamide, in water

N-sodium-N-chloro-ρ-toiuenesulfonamide (chloramine-T) effectively controls bacterial gill disease (BGD) in cultured fishes. BGD, a common disease of hatchery-reared salmonids, causes more fish losses than any other disease among these species. This study describes a liquid chromatographic (LC) method that is capable of direct, simultaneous analysis of chloramine-T and its primary degradation product, ρ-toluenesulfonamide (ρ-TSA), in water. The procedure involves reversed-phase (C₁₈) LC analysis with ion suppression, using 0.01 M phosphate buffer at pH 3. The mobile phase is phosphate buffer-acetonitrile (60 + 40) at 1 mL/min. Both chemicals can be detected with a UV spectrophotometer at 229 nm; the method is linear up to 40 mg chloramine-T or ρ-TSA/L. Mean recoveries were 96.4 ± 6.1% for water samples fortified with 0.03 mg chloramine-T/L and 95.3 ± 4.6% for water samples fortified with 0.005 mg ρ-TSA/L. Limits of detection without sample enrichment for chloramine-T and ρ-TSA are 0.01 mg/L and 0.001 mg/L, respectively.