The stability of four organophosphorus insecticides in stored cucumber samples is affected by additives

The influence of some additives, including metal ions, antioxidants, enzyme inhibitors and organic solvents, on the storage stability of four organophosphorus pesticides in cucumber samples were investigated. It was found that metal ions, including Al³⁺, Fe³⁺, and Co²⁺, increased the stability of dichlorvos, malathion, and chlorpyrifos. Conversely, Al³⁺, Fe³⁺, Fe²⁺, and Co²⁺ caused catalytic degradation of diazinon. With the addition of organic solvents (CH₂Cl₂, CHCl₃, CCl₄, CH₃OH and CH₃COCH₃), remaining of diazinon residues was higher (16-54%) after storage for seven days. CCl₄ was associated with the highest retention of malathion, diazinon, and chlorpyrifos (33%, 48% and 44%, respectively) in samples. SDS also stabilized the pesticides since residues were, again, higher (13-38%) after seven days storage. Furthermore, addition of Al³⁺ and Fe³⁺ decreased peroxidase (POD) activity and inhibited degradation of dichlorvos and malathion. After 14 days, lyophilization increased the pesticide residues remaining by 36%, 29%, and 58% for diazinon, malathion and chlorpyrifos, respectively. Overall, the stability of these pesticides during storage is impacted by water content and addition of exogenous substances. This could ensure higher quality of pesticide residue data in samples.