Residue Analysis And Pharmacokinetics Of Veterinary Drugs In Exported Aquatic Products Of Shandong Province

China is the largest trading country for aquatic products in the world, and a high proportion of aquatic products from aquaculture. However, various drugs applied for aquaculture with an aim to control the diseases of aquatic animal have declined the quality of seafood and reduced the export amount in the international markets. The residue drugs in seafoods have been detected in many aquatic samples including some banned drugs and over standard allowed drugs. It is thus important to set up the detection technology and pharmacokinetics of veterinary drugs to monitor and control the application of drugs in aquaculture processes.In this study, the nitrofuran metabolite residues in the processed aquatic products were detected and the interfering factors in detection were analyzed; and the methods to analyze four kinds of nitrofurans simultaneously in feeds using high performance liquid chromatography (HPLC) was established. Moreover, the ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method was established to detect the residues of sulfonamides, quinolones and tetracyclines in different tissues of stone flounder (kareius bicoeoratas). Then it was studied that the pharmacokinetics for sulfamethazine, sulfamethoxazole, enrofloxacin, difloxacin and oxytetracycline in stone flounder, and the withdrawal periods were determined. Base on these studies, the prevention and control measures were proposed for management. The detailed results were summarized as below:1. The study on banned drug nitrofurans and its metabolites residues in seafoodA method was established to detect four kinds of nitrofurans in feeds through the experiments. The samples were extracted by acetonitrile, purified by hexane and acidic alumine, and then detected by HPLC. The LOD and LOQ for furacillin, nitrofurantion and furaltadone were0.15mg/kg and0.5mg/kg, and for furazolidone were0.12mg/kg and0.075mg/kg, respectively. The average recoveries of the four nitrofurans were more than75%, with RSD below10%. When the methods using to analyze the metabolites residues of nitrofurans in Japan and China were compared, it was found that the significance interferinge factors determining semlcarbazide hydrochloride (SEM) were the sodium hypochlorite in the aquatic products processing and azodicarbonamide in flour. The difference between detection methods and the use of ethanol in aquatic products processing had no effects.2. The method for simultaneous determining the residues of27kinds of sulfonamides (SAs) and quinolones (QNs) The samples were extracted with acetonitrile saturated by hexane containing1%formic acid, cleaned-up by hexane, and then analyzed by UPLC-MS/MS. The mass spectrometer was operated in the positive ion mode using multiple reactions monitoring (MRM) mode for the qualitative and quantitative analysis of27kinds of SAs and QNs at the same time. The standard curves for all compounds were linear over the concentration range of10.0-100.0μg/kg, with correlation coefficients of more than0.997. The average recoveries of27kinds of SAs and QNs in the muscle, blood and liver of stone flounders ranged from75.1%-110.3%with relative standard deviations (RSD) less than12%, and the limits of quantitation (LOQ) were6.0-10.7μg/kg.3. The method for the simultaneous determining of the residues of4kinds of tetracyclines (TCs)The samples were extracted with acidic buffer solution, cleaned up by Oasis HLB solid phase extraction column, and then analyzed by UPLC-MS/MS. The mass spectrometer was operated in the positive ion mode using MRM mode for the qualitative and quantitative analysis of4kinds of TCs at the same time. The standard curves for all compounds were linear over the concentration range of5.0-200.0μg/kg and the correlation coefficients ranged from0.9982to0.9996. The average recoveries of4kinds of TCs in the muscle, blood and liver of stone flounders were all more than76.0%with the RSD less than11%and the LOQ were4.3-8.3μg/kg.4. The pharmacokinetics of restricted-using drugsThe metabolisms of5kinds of restricted-using drugs (sulfamethazine, sulfamethoxazole, enrofloxacin, difloxacin and oxytetracycline) were studied in stone flounders with oral gavage and mixed-feed gavage at15±2℃. The result showed that the metabolism rates of drugs in oral gavage for stone flounders were arranged as the following:plasma>muscle>liver (sulfamethazine, enrofloxacin, difloxacin and oxytetracycline), muscle>liver>plasmare (sulfamethoxazole). The metabolism rates of drugs in mixed-feed gavage were arranged as plasma>muscle>liver(sulfamethazine, enrofloxacin and difloxacin), muscle>plasma>liver (sulfamethoxazole and oxytetracycline). According to these results, the withdrawal periods in mixed-feed gavage for sulfamethazine, sulfamethoxazole, enrofloxacin, difloxacin and oxytetracycline (100mg/kg,100mg/kg,20mg/kg,20mg/kg and50mg/kg body weight) were determined and they were28,28,26,28and26days, respectively.