The optimization and establishment of QuEChERS-UPLC-MS/MS method for simultaneously detecting various kinds of pesticides residues in fruits and vegetables

Abstract

Objectives: The quality safety supervision and test of agricultural products urgently need a very excellent analytical method with simultaneously detecting many components in order to assess, prevent and control pesticide residues.

Methods: In this research, three fruits and three vegetables produced in Shanghai were selected as the materials, 54 pesticide residues were detected with the ultra-high performance liquid chromatography-tandem mass spectrometric (UPLC-MS/MS) method on the basis of optimized QuEChERS method according to different materials properties.

Results: The results showed that: all samples were directly extracted by acetonitrile containing 1% (v/v) acetic acid; complex matrix samples were purified by a mixed sorbent of 300mg MgSO₄+100mg PSA+100mg C18+0.01g Carb, general matrix samples didn't add Carb, simple matrix samples such as watermelon directly filmed; Chromatographic column was ZORBAX Eclipse Plus-C18 column (3.0mm×150mm, 3.5μm) at 40°C, the methanol-water of mobile phase at a flow rate of 0.45mL/min by a gradient elution contained 0.1% formic acid and 5mmol/L ammonium acetate and the injection volume was 1μL. With switching electrospray ion source polarity, [M-H]^- and high sensitive [M+Na]^＋were respectively the precursor ions of eight pesticides and avermectin, [M+H]^＋ was those of the else 45 pesticides. The detection parameters of multi-reactions monitoring (MRM) with simultaneously positive and negative ions (electron multiplier voltage was 200V) scanning were set as follows: the 310.3kPa of nebulizer pressure, the 300°C of drying gas temperature, the 7L/min of drying gas flow, the 3000V and 3500V of respectively capillary positive and negative voltage. With the optimized method, the calibration curves of 54 pesticides were better linear in 15-500μg/kg (r ≥0.988), the average adding standard recovery rates of 54 pesticides were 73.2%-134.3% except pymetrozine and cyromazine with the relative standard deviations (RSD) of 1.0%-13.8%; the limit of detection (LOD) under three times signal-to-noise ratio (S/N) and limit of quantitative (LOQ) under 10 times S/N were respectively confirmed 0.003-2.000μg/kg and 0.01-6.67μg/kg.

Conclusions: The results demonstrated that the optimized "QuEChERS-UPLC-MS/MS method" was a simple, rapid, sensitive, accurate, efficient, economical and safe method that simultaneously detected multiple pesticide residues through one time sample treatment; It had some advantages such as more pesticides per detection, simple and convenient pretreatment and less solvent dosage to be suitable for the quick high-throughput quantitative screening and confirmation of pesticide residues in fruits and vegetables.

Keywords: Fruit; Pesticide residue; Ultra-high performance liquid chromatography-tandem mass spectrometric (UPLC–MS/MS); Vegetable.