Storage stability improvement of organophosphorus insecticide residues on representative fruit and vegetable samples for analysis.

Accuracy of data for pesticide residues analysis is particularly important because analytical results are the basis for risk assessment and taking regulatory action. We, therefore, investigated the storage stability of eight organophosphorus pesticides on seven different kinds of matrices under different conditions; and the improvement measures of the stability of five pesticides on cabbage and potato were studied. The results confirmed the reduction of pesticide residue levels over time due to the storage conditions, the properties of the pesticide and characteristics of the matrices. It was found temperature was most important for stability and had the greatest effect on diazinon, pirimiphos‐methyl, and methidathion. Another promising finding was that adding the copper ion, sulfur powder, methanol, dichloromethane, and adjusting pH to acidity could improve the stability of the five pesticides. The results indicated that methods to apply some extra substrates need to be identified and intensively studied to improve storage stability of organophosphorus pesticides. Practical applications: Undesired loss of pesticides at the sample storage stage and subsequent analytical steps will result in an underestimate of residue levels with possible implications on MRL compliance monitoring, risk assessments, and measurement uncertainty. Regulatory agencies can no longer afford to ignore the contribution of storage stability to the uncertainty results owning to the high risks involved. Our research topic is how to improve storage stability. These measures can be applied to actual production and have important significance for the evaluation of unstable pesticides during storage. This also provides data support and research basis for future storage stability studies. [ABSTRACT FROM AUTHOR]

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