Determination of eight pesticides in Lycium barbarum by LC-MS/MS and dietary risk assessment

A LC-MS/MS method for determination of eight pesticides (triadimefon, sulfoxaflor, flusilazole, tebuconazole, difenoconazole, amitraz, azoxystrobin, and thiophanate-methyl) in Lycium barbarum was established. The samples were extracted with acetonitrile, and then cleaned up by primary secondary amine. The extracts were diluted with 0.1% formic acid in water. The results showed that at the fortified levels of 0.01-10 mg/kg, the average recoveries of these pesticides ranged from 82.1% to 96.2% with the relative standard deviations lower than 7%. The half-lives of eight pesticides were 1.3-5.0 days in Lycium barbarum fruits. The pre-harvest interval of all pesticides mentioned above were investigated. Tebuconazole (14 days), sulfoxaflor (14 days) and fiusilazole (28 days) have longer pre-harvest interval than the others which have 7 days. The dietary risks, assessed as hazard quotients, were far below 100%. The results showed that the eight pesticides applied to Lycium barbarum were comparably safe for the consumer. (C) 2016 Elsevier Ltd. All rights reserved.