Performance of a proposed determinative method for p-TSA in rainbow trout fillet tissue and bridging the proposed method with a method for total chloramine-T residues in rainbow trout fillet tissue

Chloramine-T is an effective drug for controlling fish mortality caused by bacterial gill disease. As part of the data required for approval of chlora mine-T use in aquaculture, depletion of the chloramine-T marker residue (pa ra-toluenesulfonamide; p-TSA) from edible fillet tissue of fish must be cha racterized. Declaration of p-TSA as the marker residue for chloramine-T in rainbow trout was based on total residue depletion studies using a method t hat used time consuming and cumbersome techniques. A simple and robust meth od recently developed is being proposed as a determinative method for p-TSA in fish fillet tissue. The proposed determinative method was evaluated by comparing accuracy and precision data with U.S. Food and Drug Administratio n criteria and by bridging the method to the former method for chloramine-T residues. The method accuracy and precision fulfilled the criteria for det erminative methods; accuracy was 92.6, 93.4, and 94.6% with samples fortifi ed at 0.5X, 1X, and 2X the expected 1000 ng/g tolerance limit for p-TSA, re spectively. Method precision with tissue containing incurred p-TSA at a nom inal concentration of 1000 ng/g ranged from 0.80 to 8.4%0. The proposed det erminative method was successfully bridged with the former method. The conc entrations of p-TSA developed with the proposed method were not statistical ly different at p < 0.05 from p-TSA concentrations developed with the forme r method.