Difenoconazole and linuron dissipation kinetics in carrots under open-field conditions.

The dissipation of difenoconazole and linuron using an open-field experimental approach with carrots exposed to one-, two- and fivefold the recommended dose of the pesticides was evaluated to provide safe recommendation to ensure food safety of carrots. The pesticide residue analysis was performed with solid-liquid extraction with low temperature partitioning technique (SLE/LTP) followed by gas chromatography analysis. The recovery percentages of extracts obtained from samples of carrot passed through SLE/LTP extraction and fortified with difenoconazole and linuron pesticides varied from 93.4% to 106.3% and from 95.1% to 116.6%, respectively. The limit of detection for difenoconazole was 0.02 and 0.12 mg kg-1 for linuron. The limit of quantification for difenoconazole was 0.05 and 0.36 mg kg-1 for linuron. The degradation time for fifty percent of the applied pesticide at the different doses ranged from 2.4 to 3.6 days for difenoconazole and from 7.5 to 10.5 days for linuron. At the end of the pre-harvest interval, carrots treated with fivefold the recommended dose of both pesticides were considered unfit for consumption. Despite monitoring the degradation products of the applied pesticides by gas chromatography coupled to mass spectrometer, none degradation product was identified on the carrots.

Ozone treatment for pesticide removal from carrots: Optimization by response surface methodology.

The present study aimed to optimize ozone (O3) treatments, as gas and dissolved in water, to remove difenoconazole and linuron in carrots. We employed a central composite design to study three variables governing the efficacy of treatments: O3 concentration, temperature and treatment time. The temperature did not influence the efficacy of treatments. The removal percentage of pesticides increases with increases in ozone concentration and the time of treatment. O3 application promoted the removal of more than 80% of pesticides when the roots were exposed for approximately 120min at 5 and 10mgL-1, respectively, in treatments with O3 as gas and dissolved in water. After storage, pesticide removal was higher than 98% for difenoconazole and 95% for linuron. The degradation products from the pesticides resulting from treatment were monitored, but none were found. This is the first report demonstrating the removal of difenoconazole and linuron from carrots by ozone.