Distribution and migration study of pesticides between peel and pulp in grape by online gel permeation chromatography–gas chromatography/mass spectrometry
A multi-residue method for the analysis of 175 pesticides was developed by online gel permeation chromatography–gas chromatography/mass spectrometry (GPC–GC/MS) to study pesticide distribution and migration between peel and pulp in grape. The separated peel and pulp samples were extracted by acetonitrile after fortified with chlorpyrifos-d10 isotope internal standard. The extract was first purified by solid phase distribution sorbent of primary secondary amine (PSA) and then detected by online GPC–GC/MS. At the spiking levels of 10, 50 and 200 Î¼g kg−1, 73.7%, 94.3% and 98.9% of the pesticides, respectively, presented recoveries between 70% and 120%. The ratios were 91.4%, 94.9% and 92.0%, respectively, for the relative standard deviations (RSDs) bellow 15%. Limits of detection (LODs) for the pesticides in pulp were below 10 Î¼g kg−1. Pesticides were separated to four groups according to the distribution ratios (peel/whole grape) of 100%, 80–99.9%, 50–80% and 0–50% in peel. Relationship between the pesticide distribution and corresponding regulation of EU maximum residue level (MRL) was discussed. Six factors influencing the pesticides distribution and migration between peel and pulp were discussed. Weak linear correlation between the pesticide solubility in water (20 °C) and the distribution ratios (lowest and average) in peel was found for most of the detected pesticides with solubility less than 200 mg L−1. âº Distribution and migration of pesticide between peel and pulp in grape were studied. âº Online GPC–GC/MS was used to detect target and non-target residue pesticides. âº Different pesticides behave different migration and distribution mechanism.