Selective determination of diazinon and chlorpyrifos in the presence of their degradation products: Application to environmental samples

Abstract

An accurate, sensitive, and selective HPLC method was developed and validated for the determination of diazinon and chlorpyrifos. These pesticides were subjected to different stress conditions, such as acidic, alkaline, oxidative, thermal, and photolytic hydrolysis. The proposed method used a C18 Eclipse Plus column (100 × 4.6 mm, 3.5 µm) and a mobile phase consisting of acetonitrile-water (70 + 30, v/v) in an isocratic separation mode. The flow rate was 1.5 mL/min, with UV detection at 247 and 230 nm for diazinon and chlorpyrifos, respectively. The proposed method was linear over the range of 0.40-50.00 µg/mL for diazinon and 0.40-40.00 µg/mL for chlorpyrifos. The proposed method was validated per International Conference on Harmonization guidelines and subsequently applied for the successful determination of the studied pesticides in bulk form in their commercial samples in the presence of their degradation products. The developed method was used for the determination of the residues of these pesticides in lavender and rosemary leaves that were pretreated with the recommended doses of these pesticides.