Method validation for simultaneous determination of four neonicotinoids in vegetables by liquid chromatography

Pesticides are widely employed to boost the production of vegetable crops, but their indiscriminate application leaves residue in the crops for long, even after harvesting. Among pesticides, neonicotinoids are the most commonly applied group of insecticides which are used on vegetables to defend against a variety of sucking pests. The purpose of this study was to validate an analytical approach focused on QuEChERS extraction for the validation and simultaneous determination of residues of four neonicotinoids (imidacloprid, clothianidin, acetamiprid and thiamethoxam) in six diverse crops such as cucumber, brinjal, tomato, beans, cabbage, and cauliflower. Insecticides were quantified using high-performance liquid chromatography (HPLC) fitted with a UV-Vis detector. Specificity, linearity, precision, accuracy, limit of detection, and the limit of quantification were all considered for validation. The fortification of the vegetables was done at three different levels (0.2, 0.3 and 0.5 µg mL^-1), for confirming the validity of the method adopted. The results demonstrated adequate recoveries ranging from 77.5 to 96.4% and good accuracy (RSDs between 0.3 and 8.9%). For all the insecticides, the approach had good linearity with R² ≥ 0.99. The limit of detection (LOD) and the limit quantification (LOQ) levels of all the four analytes were 0.05 µg mL^-1 and 0.2 µg mL^-1, respectively. The validation characteristics of the devised method are satisfactory in terms of specificity, linearity, precision, accuracy, limit of detection and limit of quantification and thus can be successfully employed for simultaneous determination of the neonicotinoids.