Meinertz, J.R. and L.J. Schmidt. 1998. Liquid chromatographic determination of para-
toluenesulfonamide in the edible fillet tissue from three species of fish. Final report 
submitted to the Center for Veterinary Medicine, U.S. Food and Drug Administration, 
May 19, 1998. 694 pages.
Summary
Bacterial gill disease (BGD) is a predominant disease of fish cultured in crowded 
conditions and is responsible for substantial production losses on federal, state, and 
commercial hatcheries. Chloramine-T (n-sodium-n-chloro-p-toluenesulfonamide) is a 
disinfectant that is a candidate therapuetant for treating BGD.
An attribute of a drug that must be characterized before approval by the U.S. Food and 
Drug Administration is depletion of the drug’s marker residue (the drug’s residue of 
regulatory concern) from edible tissues. Para-toluenesulfonamide (p-TSA) is the primary 
degradation product and marker residue for chloramine-T. In order to conduct residue 
depletion studies for chloramine-T, a robust analytical method sensitive and specific for 
p-TSA residues in edible fish fillet tissue was developed. Homogenized fillet tissue from 
rainbow trout (Oncorhynchus mykiss), walleye (Stizostedion vitreum), and channel 
catfish (Ictalurus punctatus), was fortified at nominal p-TSA concentrations of 17, 67, 
200, 333, and 1000 ng/g. Samples were analyzed by isocratic reversed-phase liquid 
chromatography (LC) with absorbance detection at 226 nm. Mean recoveries of p-TSA 
from the three fish species ranged from 77% to 93.17 %, relative standard deviations 
ranged from 1.5 % to 14 %, and method quantitation limits ranged from 13 ng/g to 18 
ng/g. The LC parameters produced easily integratable p-TSA peaks without co-elution of 
endogenous compounds and prevented chromatographic interferences from at least 
twenty chemicals potentially used in aquaculture.