Liquid chromatographic determination of para-toluenesulfonamide in edible fillet tissues from three species of fish

Chloramine-T (N-sodium-N-chloro-p-toluene-sulfonamide) is a candidate thera peutic drug for treating bacterial gill disease, a predominant disease of a variety of fish species. Research has been initiated to obtain the U.S. Fo od and Drug Administration's (FDA) approval for the use of chloramine-T on a variety of fish species. An attribute of a therapeutic aquaculture drug t hat must be characterized before the FDA approves its use is depletion of t he drug's marker residue (the drug's parent compound or metabolite of highe st concentration in an edible tissue). para-Toluenesulfonamide (p-TSA) is t he primary degradation product and marker residue for chloramine-T in rainb ow trout. To conduct residue depletion studies for chloramine-T in fish, a robust analytical method sensitive and specific for p-TSA residues in edibl e fillet tissue from a variety of fish was required. Homogenized fillet tis sues from rainbow trout (Oncorhynchus mykiss), walleye (Stizostedion vitreu m), and channel catfish (Ictalurus punctatus) were fortified at nominal p-T SA concentrations of 17, 67, 200, 333, and 1000 ng/g. Samples were analyzed by isocratic reversed-phase liquid chromatography (LC) with absorbance det ection at 226 nm. Mean recoveries of p-TSA ranged from 77 to 93.17%; relati ve standard deviations ranged from 1.5 to 14%; method quantitation limits r anged from 13 to 18 ng/g; and method detection limits ranged from 3.8 to 5. 2 ng/g. The LC parameters produced p-TSA peaks without coelution of endogen ous compounds and excluded chromatographic interference from at least 20 ch emicals and drugs of potential use in aquaculture.