Dynamic Analysis of Pesticide Degradation in Off-Season Vegetables Stored in Frozen Conditions

Nowadays, public concern over food safety, especially the potential health risk to humans cause by the high levels of pesticide residues, has increased. In general, people usually refrigerate fresh vegetable in order to keep their freshness intact for longer duration of time. Very few research studies have investigated the correlation between refrigerated vegetables and degradation of pesticide residue. Gas chromatography was used to conduct dynamic analysis of pesticide degradation in off-season vegetables, which are kept in cold storage conditions. Cowpea and balsam pear samples were extracted with acetonitrile. The resultant extracts were purified in SPE column filled with cleanert pesticarb. Thereafter, the eluant extracts were determined through gas chromatography coupled with μECD. Matrix-matched calibrations were analyzed through GC-ECD, where in the limits of quantification varied between 0.0005 and 0.0026mg/kg. The linear coefficients of correlation varied between 0.9916 and 0.9997. Recoveries on cowpea and balsam pear were in the range 74.7%~98.8%. Based on the residue dynamics study, the half-lives of the five pesticides in cowpea were as follows: chlorpyrifos: 247d, chlorfenapyr: 407d, bifenthrin: 462d, cyhalothrin: 346d, and cis-cypermethrin: 315d. In balsam pear samples, the half-lives of the five pesticides were as follows:chlorpyrifos: 150d, chlorfenapyr: 187d, bifenthrin: 433d, cyhalothrin: 266d, and cis-cypermethrin: 210d. The residue of five pesticides in cowpea and balsam pear underwent slow degradation in cold storage conditions. In this study, the findings serve as important reference data, which can be used by the concerned state authorities in formulating the limit of pesticide residue in food.