The effect of household processing on the decline pattern of dimethomorph in pepper fruits and leaves

•QuEChERS and LC/MS/MS were used to determine dimethomorph residues in pepper fruits and leaves.•The method was validated for accurate and precise quantitation.•Washing and boiling significantly decreased the residue levels in pepper fruits.•Drying after washing and parboiling significantly attenuated the residues in pepper leaves.

The effects of various household processes, including washing, boiling, frying, parboiling, and drying under different conditions (water amount, boiling times, and temperatures) on the residual levels of dimethomorph were evaluated in pepper fruits and leaves grown under plastic greenhouse conditions. The original quick, easy, cheap, effective, rugged, safe (QuEChERS) method (after modification) and liquid chromatography-tandem mass spectrometry (LC/MS/MS) were used for extraction and analysis to determine the sample residues. The results of recovery tests in processed and unprocessed pepper fruits and leaves ranged from 73.6 to 106.2% with relative standard deviations of 1.62-12.4%. Among various processes, washing and parboiling (78.4-85.8% at single and 75.7-89.9% at double dose) and drying after washing and parboiling (95.3-97.3% at single dose) were the most effective household methods to attenuate the analyte residues in pepper fruits and leaves, respectively. We conclude that processing leads to extensive reduction of pesticide residue levels in pepper fruits and leaves, particularly following washing and cooking operations.