Degradation behavior and products of malathion and chlorpyrifos spiked in apple juice by ultrasonic treatment
Apple juice (13 °Brix) spiked with malathion and chlorpyrifos (2-3 mg l-1 of each compound) was treated under different ultrasonic irradiations. Results showed that ultrasonic treatment was effective for the degradation of malathion and chlorpyrifos in apple juice, and the output power and treatment time significantly influenced the degradation of both pesticides (p 2 ≥ 0.90). The kinetics parameters indicated that chlorpyrifos was much more labile to ultrasonic treatment than malathion. Furthermore, malaoxon and chlorpyrifos oxon were identified as the degradation products of malathion and chlorpyrifos by gas chromatography-mass spectrometry (GC-MS), respectively. The oxidation pathway through the hydroxyl radical attack on the P{double bond, long}S bond of pesticide molecules was proposed.