Comparison of Sample Pretreatment Methods for the Determination of Imidacloprid Residue in Agricultural Products by High Performance Liquid Chromatography

The aim of this study was to develop a high performance liquid chromatography (HPLC) method for the determination of imidacloprid residue in agricultural products. Different extraction and purification methods were compared for their applicability in the sample pretreatment procedure. Samples were extracted with acetonitrile and the extract was concentrated and purified using a WondaSep GC-e/PSA SPE cartridge. The target compound was separated on an XBridge C18 column using 0.1% phosphoric acid-acetonitrile as the mobile phase under gradient elution mode, detected with a diode-array detector and quantified by external standard method. The effect of water added to agricultural products on the extraction of imidacloprid was examined, and solid phase extraction (SPE) and the quick, easy, cheap, effective, rugged, and safe (QuEChERS) method were compared for their efficiency in removing interfering matrices. The results showed that different extraction and purification methods had different effects on different agricultural products. The method developed in this study showed good linearity with correlation coefficients (R2) greater than or equal to 0.999 in the concentration range of 0.05 to 10.0 μg/mL. The average recoveries of the analyte were between 88.3%-109.1%, with relative standard deviations (RSDs) less than 3.5%. This method can provide strong technical support for the monitoring of imidacloprid residues in agricultural products. © 2019, China Food Publishing Company. All right reserved.