Abstract
The effectiveness of running water (H2O), hydrogen peroxide (H2O2), potassium permanganate (KMnO4), citric acid (CA) and acetic acid (AA) at concentrations of 1 and 2% for different dipping times was determined as postharvest washes for removing chlorpyrifos form date fruits treated at a concentration of 2 ppm. The recovered amount of chlorpyrifos was extracted based on the solid phase extraction (SPE) and then analyzed by gas chromatography with mass spectrometry (GC-MS). Results demonstrate that the removing of chlorpyrifos increased in the order of AA>CA>H2O2>KMnO4>H2O only. Also, the results showed that the percent of pesticide residue on date fruits depended on the concentration of tested washing treatments and dipping time. The formation of toxic by-product (chlorpyrifos oxon) was studied using gas chromatography-mass spectroscopy (GC-MS) analysis technique. No toxic by-product was identified in the extract of date fruits. Kinetic studies revealed that chlorpyrifos was found to be more easily removable from date fruits treated with the tested chemical solutions with t(1/2) values of 12-29 min compared with roughly 53 min in case of running water. The use of these washing treatments especially AA for removing chlorpyrifos as postharvest treatment may be an effective method. Studies are in progress to determine the impact of these washing treatments on the quality of date fruits.