Effects of Processing on the Disappearance of Pesticide Residues in Fresh-cut Lettuce

The aim of this research was to investigate the effects of different treatments on five pesticide residues in the preparation of fresh cut lettuce and to assess the health risk of pesticide residues. A field study was carried out on the dissipation of three insecticides(imidacloprid,tebufenozide,cypermethrin)and two fungicides(tebuconazole,azoxystrobin)during treatment conditions simulating those used for commercial fresh-cut lettuce. A method was developed for the determination of 5 pesticide residues in lettuce by purification of ethylenediamine-N-propyl silane(Primary secondary amine,PSA)filler dispersion solid phase extraction based on acetonitrile,coupled with gas chromatogramphytriple quadrupole mass spectrometry(CG-MS)and liquid chromatogramphytriple quadrupole mass spectrometry(LC-MS/MS). The results showed that all 5 pesticide residues showed significant decrease in sodium hypochlorite washing(P<0.05). The processing factors of cutting,washing,centrifuging and drying for all 5 pesticide in the whole lettuce were generally less than 1,the whole process has greatly reduced the level of pesticide residues。The bioavailability of these five pesticides in the in vitro simulated environment of gastrointestinal did not reach 50%.At different addition levels,the bioavailability was successively as follows:Cypermethrin>pyrazole>pyrazole>imidacloprid>acylhydrazide. In terms of human health risk,it was found that tebufenozide was the safest among the three insecticides combined with the allowable daily ntake(ADI)value of the tested pesticide,imidacloprid was safer than cypermethrin,and fungicide azoxystrobin was safer than tebuconazole. The conclusion was that the pesticide residues in lettuce could be removed by processing,and the dietary exposure can be reduced,which is of positive significance to ensure the dietary safety of consumers.