Meinertz, J.R., G.R. Stehly, S.L. Greseth, and W.H. Gingerich. 2001. Development of a 
Regulatory Method for p-TSA in the Edible Fillet Tissue of Channel Catfish and 
Walleye; Evaluation of Readiness to Perform. Final report submitted to the UMESC 
archives March 23, 2001 and submitted to the Center for Veterinary Medicine, U.S. Food 
and Drug Administration, September 28, 2001. 763 pages.
Summary
Waterborne exposure to chloramine-T is an effective treatment for controlling bacterial 
gill disease in fish. Currently, data are being generated to gain U.S. Food and Drug 
Administration (FDA) approval for the use of chloramine-T in aquaculture. As part of the 
data required to gain FDA approval, depletion of the chloramine-T marker residue (para-
toluenesulfonamide; p-TSA) from the edible fillet tissue of exposed fish must be 
determined. Before a depletion study can be conducted, a regulatory method for 
determining p-TSA concentrations in fish fillet tissue must be validated according to 
FDA guidelines.
A method developed at the Upper Midwest Environmental Sciences Center (UMESC) to 
determine p-TSA concentrations in edible fillet tissue of three freshwater fish species was 
submitted to the FDA for review. Although the FDA response was favorable, the 
reviewers suggested appending the data supporting the method before the method is used 
in p-TSA residue depletion studies. In response to specific suggestions by the FDA, the 
following study tasks were created: 1) evaluate the method accuracy and precision with 
channel catfish (Ictalurus punctatus) and walleye (Stizostedion vitreum) edible fillet 
tissue fortified with p-TSA at 500 ng/g (0.5X the expected 1000 ng/g tolerance limit for 
p-TSA), 1000 ng/g (1X the expected tolerance limit for p-TSA), and 2000 ng/g (2X the 
expected tolerance limit for p-TSA); and 2) evaluate the method precision with edible 
fillet tissue from at least five channel catfish and at least five walleye containing incurred 
p-TSA after exposing the fish to chloramine-T.
The method accuracy with channel catfish fillet tissue was 97.4 % with samples fortified 
at 500 ng/g, 92.6 % with samples fortified at 1000 ng/g, and 91.6 % with samples 
fortified at 2000 ng/g. The method precision with channel catfish fillet tissue containing 
incurred p-TSA at a nominal concentration of 1000 ng/g ranged from 0.99 to 5.8 %.
The method accuracy with walleye fillet tissue was 90.9 % with samples fortified at 500 
ng/g, 91.6 % with samples fortified at 1000 ng/g, and 87.9 % with samples fortified at 
2000 ng/g. The method precision with walleye fillet tissue containing incurred p-TSA at a 
nominal concentration of 1000 ng/g ranged from 0.99 to 9.9 %.