Selective Depletion of Chiral 4-Hydroxypraziquantel Metabolites in Three Types of Aquaculture Fish by LC-MS/MS

The rise of aquaculture has necessitated the use of antibiotics and other agents in these densely populated and often closed environments. An enantioselective depletion study of four chiral 4-hydroxypraziquantel metabolites (4-OH-PZQ) in perch, tilapia, and ricefield-eel muscles was done using a simple, sensitive, and reliable liquid-chromatography tandem-massspectrometry (LC-MS/MS) method. These metabolites result from the uptake of the drug praziquantel (PZQ), which is used in aquaculture. A novel strategy of using a C18 short column in tandem with a chiral hydroxypropyl-fi-cyclodextrin superficially porous particle (CDShell-RSP) column produced the optimal separation for both the enantiomers and diastereoisomers of 4OH-PZQ The method was linear over the concentration range of 1-250 mu g L-1 (r(2) > 0.99) for R-trans-4-OH-PZQ S-trans-40H-PZO, R-cis-4-OH-PZQ and S-cis-4-OH-PZQ The average recoveries of four analytes at three spiked levels of 1, 10, and 100,ug kg-1 ranged from 84.2 to 93.1%, and the intraday and interday relative standard deviations were less than 7.9%. The limits of quantification of the four 4-OH-PZQmetabolites in perch-, tilapia-, and ricefield-eel-muscle matrices were 1.0 ktg kg-1. The method was utilized to monitor the depletion of trans- and cis-4-OH-PZQenantiomers in perch, tilapia, and ricefield-eel muscle following oral administration (medicine bath for ricefield eel). Species-specific differences in the PZQ metabolism of isomers were observed. In addition, new metabolites of PZQwere observed: 3-hydroxypraziquantel diastereomers.