Hydrophilic molecularly imprinted dispersive solid-phase extraction coupled with liquid chromatography for determination of azoxystrobin residues in cucumber

Abstract

The hydrophilic molecularly imprinted dispersive solid-phase extraction (HMIDSPE) coupled with liquid chromatography (LC) for the separation and the determination of azoxystrobin in cucumber was exploited. Hydrophilic molecularly imprinted microspheres (HMIMs) for azoxystrobin were synthesized through precipitation polymerization that hydroxypropyl methacrylate (HPMA) as functional monomer, ethylene glycol dimethacrylate (EGDMA) as cross-linker, azobisisobutyronitrile (AIBN) as initiator, a mixture solution of butanone (MEK) and n-heptane (V:V 7:3) as solvent. The microspheres were determined by Fourier-transform infrared spectrometry (FTIR) and scanning electron microscopy (SEM). Under the optimum DSPE conditions, the HMIMs could extract and enrich azoxystrobin very efficiently. Comparing HMIMs with C18, the average recoveries of azoxystrobin from blank cucumber samples spiked at 0.1, 0.5, and 1 mg mL−1, ranged between 85.93 and 88.89% with relative standard deviations (RSD), were 2.10–4.91%. The average recoveries of azoxystrobin that used C18 as sorbent were 56.20–60.66% with relative standard deviations (RSD) of 3.22–5.18%. The limit of detection (LOD) and the limit of quantification (LOQ) of azoxystrobin were 3.24 × 10−4 mg kg−1 and 0.005 mg kg−1, respectively. The method of HMIDSPE-LC exhibited highly efficient separation and the enrichment of azoxystrobin. The actual samples were detected free of azoxystrobin.