Stehly, G.R., J.R. Meinertz, S.L. Greseth, and W.H. Gingerich. 2001. Validation Data for 
the p-TSA Determinative Method in Fish Edible Fillet Tissue; precision and accuracy of 
the method in rainbow trout from different regions of the country, lake trout, Atlantic 
salmon, and hybrid striped bass. Submitted to the Center for Veterinary Medicine, U.S. 
Food and Drug Administration, September 28, 2001. 310 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 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 (May 19, 1998). In a recent phone conference call 
(September 21, 2000) with scientists at the CVM, additional experimental data were 
requested to support the determinative method to cover all species of freshwater fish 
cultured at public hatcheries. The request included testing the analytical method on 
fortified fillet tissue (1000 ng/g p-TSA) of rainbow trout from three regions of the 
country. The method accuracy and precision were determined for rainbow trout edible 
fillet tissue from a western and eastern U.S. state or federal hatchery, fortified with p-
TSA at 1000 ng/g (!X the expected tolerance limit). The method was previously 
evaluated with rainbow trout cultured at the UMESC (midwest). In addition, the 
analytical method was evaluated with control edible fillet tissue from Atlantic salmon (a 
cold freshwater or marine species, genera Salmo), hybrid striped bass (a scaled 
warmwater species), and lake trout (a cold freshwater species, genera Salvelinus) to test 
applicability of the method for all freshwater fish. The data were also compared with 
method results previously determined at the UMESC for walleye (a cool freshwater 
species) and channel catfish (a scaleless warm freshwater species).
The mean theoretical recovery (accuracy) ranged from 98.2 to 101 % with samples 
fortified at 1000 ng/g with a method precision ranging from 1.4 to 2.9 % (Atlantic 
salmon, hybrid striped bass, lake trout, eastern rainbow trout, and western rainbow trout). 
The absence of interfering peaks with the retention time of p-TSA indicated that the 
method was broadly applicable for the analysis of p-TSA in the edible fillet tissue from 
multiple species of freshwater fish. The accuracy and precision were similar to values 
previously obtained with rainbow trout, walleye, and channel catfish at the UMESC.