Dissipation kinetics, safety evaluation, and decontamination of residues of the combo-formulation iprovalicarb 8.4% + copper oxychloride 40.6% WG in/on grapes (Vitis vinifera L.).

A field experiment was conducted to study the dissipation behavior and decontamination of iprovalicarb and copper oxychloride in grapes. After thorough validation, the analysis was carried out by employing LC-MS/MS for iprovalicarb and AAS for copper oxychloride. The dissipation pattern of residues followed a linear first-order kinetics model for both the test fungicides. The half-life values for iprovalicarb were 9.5-13.5 days, and for copper oxychloride was 24.5 days. Based on the study, a pre-harvest interval (PHI) of 17 days is proposed for the formulation. In decontamination studies, combination treatment of 0.1% sodium bicarbonate + ultrasonication and 2% lemon water + ultrasonication has shown the highest reduction of iprovalicarb (90.02% reduction) and copper oxychloride (80.14% reduction) residues, respectively. The safety evaluation data suggest that the daily exposure at all the sampling points was less than the maximum permissible intake (MPI) calculated indicating, safety to consumers. This study will be useful for promoting effective residue management and the safe use of these chemicals for controlling fungal diseases in grapes.

The disappearance rate and risk assessment of thiacloprid residues in Asian pear using liquid chromatography confirmed with tandem mass spectrometry.

This study was undertaken to quantify the residue levels and propose the dissipation kinetics of thiacloprid formulated as suspension concentrate in field-incurred Asian pears grown under two different open-field conditions. Samples were extracted with 20% distilled water in acetonitrile; partitioned with brine water and dichloromethane; and purified with a Florisil solid phase extraction cartridge. The analyte was identified with an LC ultraviolet detector, and field-incurred samples were confirmed using LC-MS/MS. The calibration curve was linear over the range 0.05-5.0 mg/L with a satisfactory coefficient of determination (R2 = 0.9994). The limits of detection and limits of quantification (LOQ) were 0.003 and 0.01 mg/kg, respectively. The recovery rate fortified to blank samples at LOQ, 10× LOQ, and the maximum residue limit (MRL) were between 73.7 and 86.2% with relative standard deviation ≤9.0%. The residual concentrations at both sites were considerably lower than the MRL (0.7 mg/kg) set by the Korean Ministry of Food Drug Safety, with biological half-lives of 5.0 and 7.4 days, for sites 1 and 2, respectively. From the pre-harvest residue limit curve, it was predicted that if the residues were <1.13 or 1.40 mg/kg 10 days before harvest, the residue level would be lower than the MRL during harvest. Risk assessment on day 0 showed an acceptable daily intake (%) of 13.0% and 11.0% for sites 1 and site 2, respectively, which indicates that the residual amounts are not hazardous to the Korean population.