| Sodium pentachlorophenolate is an organochlorine pesticide that was once widely used for weed control,fungicide and snail control.It was later banned from widespread use because of its toxic effects on living organisms,difficulty in degradation in the environment and persistent pollution.However,sodium pentachlorophenolate shows high levels of contamination in animal fat,meat,offal and meat products because it is easily soluble in water and can spread and cause contamination of water and soil,and may also enter plants used for feed and enter animals through the action of the food chain such as livestock breeding.Therefore,the main work carried out in this study was to investigate the elimination pattern of sodium pentachlorophenolate and its metabolites in pig tissues and excreta by establishing a simple,efficient and widely applicable multi-residue assay for sodium pentachlorophenolate and its metabolites,and to perform a dietary exposure risk assessment of sodium pentachlorophenolate residues in edible tissues of pigs based on the above study.A multi-residue method for the determination of sodium pentachlorophenolate and its metabolites tetrachlorocatechol,pentachlorophenol acetate and pentachloroanisole in 13 pig-related samples including pork,fat and pig liver was developed based on the Qu ECh ERS pre-treatment method using liquid chromatography-tandem mass spectrometry（LC-MS/MS）and gas chromatography-tandem mass spectrometry（GC-MS/MS）.In the method,5 g samples were weighed and cleaned up by ultrasonication using 1%acetonitrile acetate as the extractant and 4g Mg SO4,1 g Na Cl,1 g Na3Cit 2H2O,0.5 g Na2Cit 1.5 H2O as buffer salts.Tissues containing less pigment in pork,fat,stomach,large intestine and small intestine were cleaned up by EMR,and liver,heart,spleen,lung,kidney,blood,urine and Tissues and excreta containing more pigment were cleaned up by adding PSA to EMR and analysed by LC-MS/MS for sodium pentachlorophenolate and tetrachlorocatechol and GC-MS/MS for pentachlorophenol acetate and pentachloroanisole.The method recoveries ranged from 40.5%to 119.62%and the limits of quantification ranged from 1μg/kg to 2μg/kg.The residue levels and distribution elimination patterns of PCP-Na and its metabolites in15 sites of pigs,including the administration site,dorsal spine,hind legs,fat and pig liver,were analyzed by using intramuscular injection administration method and collecting relevant samples from pigs at 7 different time points within 21 days.The results showed that PCP-Na was rapidly and widely distributed in all tissues and organs in pigs,and the total residues in the injection site and urine gradually decreased with time,while the total residues in other sites showed a trend of increasing and then decreasing.Except for the injection site,the highest total residues of PCP-Na and its metabolites were found in the lung at 10676.82μg/kg,and the main forms present were PCP-Na and PCP acetate.The relative longest elimination half-life of PCP-Na in the liver was 20.08 days.PCP-Na and PCP-acetate can be considered as targets for the detection of residues of PCP-Na.A dietary exposure risk assessment for sodium pentachlorophenate was conducted using a point assessment approach,combining dietary data,population data and 21-day residue elimination data.The results of the assessment showed that young children aged 1-3 years,adolescents aged 18-20 years,young adults aged 20-30 years,middle-aged adults aged 30-40years and older adults aged 50 years and above had a low risk of ingestion when chronically exposed to sodium PCP residues in the stomach with a%ADI between 100.16 and 104.50The%ADI was less than 100 for chronic exposure to Na-PCP residues in the stomach at all other ages,and for chronic exposure to Na-PCP residues in other tissues at all ages,indicating no significant health risk. |
