Residue And Risk Assessment Of Prochloraz And Its Metabolite During Fruit Storage Process

A residue analytical method for determine of prochloraz pesticide in orange,pear,apple?fruit,peel,pulp?were developed in this dissertation.A residue analytical method for determine of 2,4,6-trichlorophenol in apple?fruit,pulp?were established in this dissertation.The dissipation dynamics of prochloraz and 2,4,6-trichlorophenol were investigated during the storage of apple.The residue of prochloraz in fruit samples?apple,orange,pear?collected randomly from markets were determinated.The main results results are as follows.1.The residue analytical method for prochlorazThe fruit samples were extracted with acetone by mechanical shaking and cleaned up by dichloromethane extraction.Then derivatization reaction with pyridine hydrochloride was subjected and extraction with light petroleum.All the samples were detected by GC-ECD after cleaning up by filter head.As the fortified concentration were 0.2 2.0mg·kg^-1?pear fruit?,0.2 2.0mg·kg^-1?orange fruit?,0.2 2.0mg·kg^-1?apple fruit?,0.2 2.0mg·kg^-1?apple pulp?and 0.25 ⁵.0mg·kg^-1?apple peel?,the average recoveries of prochloraz were ranged between93.84%-99.18%,86.50%-97.48%,103.44%-113.65%,82.85%-114.42% and85.09%-93.90% respectively.The coefficient of variation were 3.51%-7.64%,5.40%-11.92%,2.85%-7.00%,1.55%-5.71% and 3.52%-8.61%.These results showed that the accuracy and sensitivity of the method meet the requirement of pesticide residue analysis.2.The residue analytical method for 2,4,6-trichlorophenolThe samples were extracted with acetone by mechanical shaking and cleaned up by dichloromethane extraction.Then cleaned up by Florisil SPE with 5.0 mL mixed solution?acetone : n-hexane=5:5,V/V?and 40.0 mL mixed solution?acetone :n-hexane=9:1,V/V?elution and detected by GC-ECD.The average recoveries of2,4,6-trichlorophenol in apple fruit and apple pulp at 0.02-2.0mg·kg^-1were ranged between 85.02%-89.82% and 84.65%-109.12% respectively.The coefficient of variation were 0.65%-5.19% and 1.56%-4.59%.These results showed that the sensitivity and accuracy of the method meet the requirement of pesticide analysis.3.The dissipation dynamics of prochloraz and 2,4,6-trichlorophenol were investigated during the storage of appleThe results showed that the prochloraz had a slow degradation rate during the storage of apple.The dissipation of prochloraz followed the first order kinetics.The half-life values of prochloraz in apple fruit and apple peel were 63.0d and 69.3d at room temperature?at 1.0 g·L-1 and 2.0 g·L-1?respectively.The results were 69.3d and77.0d,86.6d repectively.The residues of apple fruit need 49 d and 63 d below the MRL at room temperature?at 1.0 g·L-1and 2.0 g·L-1?.They need more than 84 d at cold storage.The residue of 2,4,6-trichlorophenol were less than 0.1 mg·kg^-1 during the storage.It is suggested that according to the recommended does of 25% prochloraz EC and storage more than 3 months.4.The residue of fruit collected from markets and risk assessmentThe residue of prochloraz in 100 orange samples,100 pear samples and 20 apple samples collected randomly from markets were determinated.The results showed that no prochloraz residue in orange samples,abou 61% of pear samples have prochloraz residue and 35% of apple samples have prochloraz.The residue of pear and apple were ranged between 0.21mg·kg^-1-0.64mg·kg^-1 and 0.23mg·kg^-1-0.86mg·kg^-1.There are no more than each MRLs in all the samples with prochloraz residue.