Residue Dynamics of Phoxim in Pericarp, Sarcocarp and Kernel of Apple

The temporal and spatial variations of phoxim residue in apples were studied. The insecticide phoxim was applied by spraying according to the recommended dosage. The phoxim residues in different parts of apple were extracted with acetonitrile, purified by primary secondary amine (PSA) and C18 filler, and then determined by gel permeation chromatography-gas chromatograph mass spectrometer (GPC-GC/MS). It was disclosed that the half-life of phoxim in apples was 1.64 days. The contents of the phoxim residue in different parts of apple could be ranked as follows : pericarp > entire apple > sarcocarp> kernel, and the ratio of residue in pericarp and the entire apple ranged from 6.241 to 9.262 in groups with different specific surface area. There were significant differences in the contents of residues between the pericarp and entire apple, which provided the evidence in the theory instruction and design basis to the sampling method of pesticide residue based on pericarp.