| Organophosphorus pesticides have the advantages of high efficacy,broad spectrum,low cost,variety,etc.,and have a relatively common application in agricultural production.Trichlorfon and Dichlorvos belong to organophosphorus pesticides and are commonly used for the prevention and treatment of crop pests,livestock and aquatic parasites in vivo and in vitro.If there are residues of these two drugs in the edible tissues of animals,long-term consumption will bring potential harm to human health.Therefore,in the course of drug use of trichlorfon and dichlorvos,the safety of human and animal residues in the residues of drugs and metabolites in edible tissues cannot be ignored.By comparing the regulations on the limits of trichlorfon and dichlorvos in animal foods at home and abroad,the limit of domestic trichlorfon is lower than that of the Codex Alimentarius Commission,the United States,and South Korea.The residual limits of domestic and foreign trichlorfon are 0.05 mg/kg and 0.1 mg/kg,separately.However,the residual limit of dichlorvos is 0.02 mg/kg at home and abroad.According to the announcement of China’s Ministry of Agriculture No.235,the maximum residue limits of trichlorfon and dichlorvos in animal edible tissues were 0.05 mg/kg and 0.02 mg/kg,separately.Bullfrog muscle and skin were repeatedly extracted with 1% glacial acetic acid-ethyl acetate extract.After centrifugation,the supernatants were combined twice.The flask was placed in a 45°C.water bath and evaporated approximately 3 to 5 mL.The impurities were removed using an acidic alumina column.The supernatant and eluent were placed on a45°C water bath and evaporated to dryness.The solution was reconstituted in 1 mL ofacetonitrile and passed through a membrane and detected by LC-MS/MS.Through the above pretreatment method,the linear relationship between the peak area and concentration of trichlorfon in the range of 0.5~100 μg/kg was good,and the relevant coefficient was biger than 0.99.the linear relationship between the area and concentration of dichlorvos in the range of 0.5~40 μg/kg was good.The relevant coefficient is biger than0.99.Under the pretreatment method,three levels of low,medium,and high levels of trichlorfon and dichlorvos were added separately to determine the added recovery and intra-assay variation of trichlorfon in bullfrog muscles.Coefficients and inter-assay coefficients of variation were 84.1% ~ 102.5%,2.1% ~ 12.2%,and 10.3% ~ 11.6%,separately.addition recovery,intra-assay coefficient of variation,and inter-assay coefficient of variation of dichlorvos in bullfrog muscle were: 79.2%~98.8%,2.9%~16.8%,9.9%~14.7%.The addition recovery,intra-assay coefficient of variation,and inter-assay coefficient of variation of trichlorfon in bullfrog skin were 73.5%~99.7%,4.8%~10.5%,and 9.0% ~9.4%,separately.The addition recovery,intra-assay coefficient of variation,and inter-assay coefficient of variation of dichlorvos in the skin of bullfrogs were 70.0%~100.0%,4.8%~12.3%,and 9.1%~17.3%,respectively.In addition,the LOD and LOQ of trichlorfon and dichlorvos in bullfrog muscles were measured to be 0.4 μg/kg,0.5 μg/kg,0.25 μg/kg,and 0.5 μg/kg,separately.trichlorfon and dichlorvos were found in the skin of bullfrogs.LOD and LOQ were 0.4 μg/kg,0.5 μg/kg,0.25 μg/kg,and 0.5 μg/kg,separately.The experimental results show that the LC-MS/MS detection method for detection of trichlorfon and dichlorvos in this study has the advantages of rapid detection,high sensitivity,good repeatability,and meets the requirements of veterinary drug residue analysis. |
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