| Bioavailability and bioaccessibility are important factors for the accurate assessment of human health risks from dietary exposure of pesticide residues.The bioaccessibility application of in vitro digestion methods of is simple and quickly,and has become an important method for evaluating the bioavailability of pesticide residues.However,current in vitro digestion methods lack dynamic absorption processes in the human intestine.In this paper,we selected five triazole fungicides(triadimefon,tebuconazole,metconazole,epoxiconazole and difenoconazole)that commonly used in fruits,and selected Tenax as an adsorbent to simulate the intestinal dynamic absorption process,combined with the IVIVC model to optimize the in vitro determination to evaluate the bioaccessibility of pesticide residues in 25 fruits,and to quantify the dietary exposure risk of pesticides in fruits.The results are useful for the scientific evaluation of pesticide residues in fruits.The results of the study are of great significance and application for the scientific evaluation of the food safety of pesticide residues in fruits and the enrichment of theories and methods for risk assessment of pesticide residues in agricultural products.The main findings are as follows.1.Establishment of analytical methods for triadimefon residues in 25 fruits and biological samples from ratsA Qu ECh ERS-UPLC-MS/MS method was developed for the residue analysis of triadimefon,tebuconazole,metconazole,epoxiconazole and difenoconazole in simulated intestinal fluid in 25 fruits.The linearity was good in the concentration range of 1～100μg/kg with the r~2of 0.9928～0.9999;the LODs of the method were 0.23～0.29μg/kg and the LOQs were 0.77～1.13μg/kg.The recoveries ranged from 70.4～119.2%with the RSDs of0.08～9.0%.The spiked recoveries of triadimefon and its metabolite triadimenol in rat biological samples such as kidney showed good linearity in the concentration range of 1～1000μg/kg with the r~2of 0.9992～0.9999;the LOD and LOQ of the method were 0.23～0.29μg/kg and0.39～0.62μg/kg,respectively.The average spiked recoveries of triadimenone and triadimenol in rat biological samples at the spiked concentrations of 0.05,0.1 and 1.0mg/kg ranged from 74.5～116.5%with the RSDs of 0.3～9.8%.The accuracy and reproducibility of the method can meet the requirements of pesticide multi-residue analysis.2.Optimization of an in vitro method for the bioaccessibility determination of triazole fungicides based on Tenax adsorption kineticTenax was selected as the adsorbent to simulate the intestinal absorption process of the RIVM method to optimize the in vitro determination of triazole fungicides bioavailable in fruits.The results of Tenax adsorption kinetics experiments showed that the increase of Tenax addition significantly increased the pesticide adsorption and decreased the adsorption time.When the mass of Tenax reached 1.0 g,the time to reach 99%adsorption equilibrium for the five triazole fungicides ranged from 42.16～93.30 min;compared with no Tenax addition,the addition of 1.0 g Tenax significantly increased the bioaccessibility of the pesticide residues for the test by 28.34～38.61%.These findings suggest that Tenax can act as an effective adsorbent to promote the dissolution of triazole pesticide residues from fruits into the intestinal fluid and thus improve their bioaccessibility.3.IVIVC model validation of Tenax improved in vitro bioavailability assayIn vivo bioavailability experiments were conducted with triadimefon as a representative pesticide in fruits.The results showed a good linear relationship between the exposure dose of triadimefon and its accumulation in the kidney of rats during a 10-day exposure cycle(r~2=0.98,p<0.01),so the kidney was selected as the bioavailability assay target.The in vivo-in vitro correlation was performed between the bioavailability determined by the in vivo assay and the bioavailability determined by the in vitro method,and the results showed that the addition of Tenax significantly improved the linear correlation between the bioavailability obtained by the RIVM method and the in vivo animal assay(correlation coefficient of The results showed that the addition of Tenax significantly improved the linear correlation(correlation coefficient of 0.8461,slope of 0.8537)between the bioavailability obtained by the RIVM method and the in vivo animal studies,and the bioavailability results obtained by the Tenax-improved RIVM method were more consistent with the real absorption and accumulation of triazole fungicides after human digestion.4.Application of Tenax improved in vitro method for determination of bioaccessibility The Tenax improved RIVM in vitro digestion model was applied to determine the bioaccessibility of the test pesticides in 25 fruits based on the maximum residue limits of five triazole fungicides in the tested fruits.The results showed that the bioaccessibility of triadimefon,tebuconazole,metconazole,epoxiconazole and difenoconazole in the 25 fruits ranged from 46.92～96.51%,48.31～119.28%,90.22～90.84%,76.34～96.44%and46.59～99.23%,respectively.The results of correlation analysis between pesticide physicochemical properties and bioavailability showed that the pungent water partition coefficient was the main influencing factor of bioavailability,and the bioavailability increased with the increase of log Kow of pungent water partition coefficient.5.Evaluation of dietary exposure risk of triazole fungicides based on bioaccessibility To further evaluate the dietary exposure risk of triazole fungicides in 25 fruits,including grapes,by applying bioaccessibility correction to the residue distribution data of the test fruits.The results showed that the NEDIs of triadimefon,tebuconazole,metconazole,epoxiconazole and difenoconazole were 0.5879 mg,1.3254 mg,0.368 mg,0.6135 mg,0.6267 mg and 0.6267 mg,respectively.The RQcs were 31.1%,70.1%,110.2%,48.5%and 99.5%,respectively.The results indicated that the dietary exposure risks for t triadimefon,tebuconazole,metconazole,epoxiconazole and difenoconazole were all within acceptable limits,while the dietary exposure risk for chlormequat chloride was relatively high. |
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