Occurrence of Pesticides in Pericarpium Citri Reticulatae and Related Products Using Syringe Filter-Based Cleanup

The study established a method of rapid cleanup using an easy to operate syringe filter and gas chromatography coupled to an electron capture detector (GC-ECD) to detect 37 pesticides in Pericarpium Citri Reticulatae and related products. The critical parameters related to clean-up efficiency were optimized. The adsorbents, which included PestiCarb (0.5 g), primary secondary amine (PSA, 0.25 g) and Florisil (1.0 g), were loaded in turn and push-pull was performed 4 times within a 1 min operating time. Under optimized conditions, the recovery of pesticides ranged from 61.6 to 128.6% at three spiked levels (25, 50, 500 µg kg-1). After analysis by GC-ECD and confirmation by gas chromatography coupled to tandem mass spectrometry (GC-MS/MS), 8 out of 57 batches of peels were found to be contaminated with hexachlorobenzene, dicofol, procymidone and p,p’-DDE (dichlorodiphenyldichloroethylene). The most frequently (10.5%) occurring pollutants were hexachlorobenzene and dicofol. In addition, 5 batches contained prohibited or restricted persistent organochlorines at levels above regulations, and 5 of these peels contained more than two pesticides.