HPLC analysis of Romet-30 in chinook salmon (Oncorhynchus tshawytscha): wash-out time, tissue distribution in muscle and liver tissues, and metabolism of sulfadimethoxine
Creators: name: Zheng, Ming
Publisher: name: University of British Columbia
Year: 2008

description: Aquaculture is a rapidly expanding industry that has contributed substantially to world-wide food production. Salmon culture constitutes an important part of aquaculture industry. The production of farmed salmon in British Columbia reached 20,000 metric tons (mt) in 1991 and 1992 and ispredicted to grow to 26,700 mt by 1995 (Smith, 1993). However, due to the high stocking density in aquaculture and occasional poor husbandry practices, the fish are predisposed to various diseases. Treatment protocols for bacterial infections include the use of antimicrobial agents such aspotentiated sulfonamides, oxytetracycline, macrolides, penicillins andquinolones. As antimicrobial residues in edible fish tissues after drug administration is of utmost concern to the consumer's health, analytical assay is required to monitor the antimicrobial residue levels in edible fish tissue. The focus of this research was to identify a "marker" tissue which would have a higher residue level than the muscle tissue, and that the ratio between this "marker" tissue and muscle tissue would be more or less consistent. An HPLC assay was developed for determination of Romet-30®residue levels in Chinook salmon muscle and liver tissues. By using ion-pairing reagent TBAH and granular sodium sulfate anhydrous during extraction, the extraction recoveries averaged 66%, 78% and 83% for OMP, SDM and N4-Ac-SDM, respectively, in muscle tissue; 61% and 72% for SDMand N4-Ac-SDM, respectively, in liver tissue. OMP could not be quantified in liver tissue due to the presence of substantial amounts of co-extracted endogenous substances. The HPLC assay had a sensitivity of 0.05 ppm for OMP, SDM and N4-Ac-SDM in muscle tissue, and a sensitivity of 0.20 ppm for SDM and N4-Ac-SDM in liver tissue. The HPLC assay was applied to the analysis of Romet-30 residues in Chinook salmon muscle and liver tissues after administration of Romet-30®. Two intubation studies were carried out. SDM was found to be detectable up to day 20 in both studies, while OMP was detectable on day 20 in the second study but was not detectable on day 20 in the first study. N4-Ac-SDM was only detectable on day 11 in both studies. However, in liver tissue, the concentration of N4-Ac-SDM was not significantly different from that ofSDM. The presence of N4-Ac-SDM in liver tissue was confirmed by LC/MS and LC/MS/MS analyses. Both studies showed significant variations of Romet-30® residue levels between individual fish. A consistent liver/muscle SDM residue ratio was not found from the current study. However, it was suggested that the liver tissuebe used as a "monitoring" tissue since the overall concentration of SDM in liver was higher than that in muscle. Finally, since the analytical assay has a sensitivity of 0.05 ppm, which is well below the tolerance level of 0.1 ppm for Romet-30® (USFDA, 1984), the muscle tissue appears to be a good target tissue for Romet-308 residue analysis.