Abstract:

The paper aims to solve the problem of simultaneous and rapid detection of 20 registered pesticide residues in lychee. An analytical method based on ultra-high performance liquid chromatography-tandem mass spectrometry was established and optimized for simultaneous determination of 7 insecticides and 13 fungicides in lychee. The whole lychee fruit were extracted with 80% acetonitrile aqueous solution and cleaned up with graphitized carbon black (GCB). Extend C₁₈ chromatographic column was used for separation and the mobile phase was acetonitrile and water by gradient elution. Electrospray ionization in positive and negative ion mode was selected, the detection mode was multi-reaction monitoring, and external standard method was used for quantification. The results showed that a good linear relationship was presented between the mass concentration and peak area of the twenty tested pesticides, and the determination coefficient was greater than 0.9990. The average recoveries of the twenty pesticides in lychee were in range of 71%-106% with the relative standard deviations (RSD) of 0.9%-9.8%, which met the requirements of residue analysis. The results demonstrated that the proposed method was convenient and effective for the quick determination of these twenty pesticides residues in lychee.

Key words: ultra-high performance liquid chromatography-tandem mass spectrometry, lychee, insecticide, fungicide, residue