Extraction of Organochlorine Pesticides from Bee Pollen by Matrix Solid-Phase Dispersion: Recovery Evaluation by GC-MS and Method Validation

Recovery studies were done with bee pollen spiked with eight organochlorine pesticides. Matrix solid-phase dispersion was used to extract pesticides from bee pollen using octadecyl silica (C18, 0.5 g) as solid support. The co-column material for clean-up (graphitized carbon and primary secondary amine) and the eluting system (acetonitrile or acetonitrile/ethyl acetate) were optimized. Pesticide recoveries were determined by GC-MS-SIM through external calibration curves. The recoveries obtained without co-column and primary secondary amine (PSA) did not differ significantly and were higher than those obtained using graphitized carbon. With PSA used as the co-column, chromatograms with low background, low intensity, and fewer peaks were acquired. Thus, primary secondary amine was used to clean up the pollen extracts. Recoveries were higher than 100 % and precisions were poor for most of the pesticides when acetonitrile/ethyl acetate was used to elute them. Therefore, acetonitrile was selected for the elution of organochlorine pesticides. The final extraction conditions were: C18 (adsorbent), primary secondary amine (co-column), and ACN (eluting solvent). Recoveries obtained ranged from 41 to 101 %.