Determination of 7 Preservatives in Citrus by QuEChERS-UHPLC-MS/MS

QuEChERS-UHPLC-MS/MS was proposed for the determination of carbendazim, 2,4-dichlorophenoxyacetic acid, prochloraz, imazalil, thiabendazole, pyrimethanil, thiophanate methyl residues in citrus. The preservatives in the samples were extracted with a mixture solution of 5% (φ) formic acid and acetonitrile, stratified by a salting-out agent. The supernatant was cleaned up with purification pipe filled with MgSO4, C18 and PSA. Hypersil Gold C18 column was used as stationary phase, and mixtures of acetonitrile and 0.15% (φ) formic acid solution in various ratios were used as mobile phase in gradient elution, then determinated by UHPLC-MS/MS. ESI and MRM were adopted in MS operated in the positive and negative ion switch mode. Linearity ranges of the 7 preservatives were found to be same between 2.00-100 μg·L-1, with lower limits of determination (10S/N) in the range of 0.02-1.2 μg·kg-1. Recovery rates at the three concentrations of 1.00, 5.00, 40.0 μg·kg-1 ranged from 80.5% to 120% with RSDs (n=8) in the range of 2.8%-9.7%.