ABSTRACT
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 0.12â¯mgâ¯kg-1 for linuron. The limit of quantification for difenoconazole was 0.05 and 0.36â¯mgâ¯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.
Subject(s)
Daucus carota/chemistry , Dioxolanes/chemistry , Linuron/chemistry , Triazoles/chemistry , Chromatography, Gas , Dose-Response Relationship, Drug , Food Safety , Limit of Detection , Pesticide Residues/analysis , Pesticides/chemistry , Reproducibility of ResultsABSTRACT
A carbon paste electrode was used for the electrochemical determination of linuron concentrations in water and vegetable extracts. Optimal conditions were established with respect to electrode activation (electrochemical pretreatment), time accumulation, potential accumulation, scan rate, and pH. The limit of detection achieved with a pre-concentration step was 23.0 µg L(-1). Recovery measurements in vegetable extract and natural water samples were in the range of 98-103%, indicating that the proposed electrochemical method can be employed to analyze linuron in these matrices. The determination results were in good agreement with HPLC results.