Tissue depletion of quinocetone and its five major metabolites in pigs, broilers, and carp fed quinocetone premix.

A residue depletion study was performed to investigate the tissue kinetics of quinocetone (1) and its major metabolites. Quinocetone and its major metabolites were simultaneously quantitated with a high-performance liquid chromatography-ultraviolet (HPLC-UV) method. A total of 25 pigs, 30 broilers, and 50 carp were fed 100 mg/kg quinocetone for 90, 42, and 60 days, respectively. Liver, kidney, muscle, and fat (skin) tissues were collected at five different withdrawal times for analysis. Results revealed that quinocetone, 1-desoxyquinocetone (2), carbonyl-reduced 4-desoxyquinocetone (4), 3-methylquinoxaline-2-carboxylic acid (5), and carbonyl-reduced dideoxyquinocetone (6) could be depleted quickly in tissues; by contrast, dideoxyquinocetone, 3, persisted for a long time in the liver. Therefore, the liver is possibly the target tissue of quinocetone, and 3 is the residual marker; the recommended withdrawal times (WDTs) are 0 days in pigs and carp and 3 days in broilers. These results provided clear monitoring tools and technical standards to evaluate the food safety of quinocetone.