Imidacloprid is a broad-spectrum neonicotinoid class insecticide with systemic action, widely used on vegetables in India for the management of sucking insect pests. The overall pesticide usage profile in gourds growing districts of Tamil Nadu showed that imidacloprid as the most commonly used insecticide. The present study aimed to develop and validate an analytical approach for detecting imidacloprid and 6-chloronicotinic acid residues in bitter gourd fruit, juice and soil using LC-EI-MS (liquid chromatography coupled with electron ionization mass spectrometry) was undertaken. The persistence pattern, effect of household processing and risk assessment of imidacloprid on bitter gourd was studied by conducting field trials at single and double doses of 20 and 40 g a.i ha-1. Calibration curves showed a good linear relationship (r2>0.99) with the concentrations (0.0025–0.5 µg mL-1) of imidacloprid and 6-chloronicotinic acid. The limit of detection and quantification of the method were 0.008 and 0.025 mg kg-1, respectively. Accuracy of imidacloprid and 6-chloronicotinic acid residue recovery was in the range of 88–101 per cent with RSD of less than six per cent in all the matrices of bitter gourd. Initial deposits of imidacloprid at 20 and 40 g a.i ha-1 were 0.68 and 1.25 mg kg-1 and the residues persisted up to 10 and 15 days with their respective half-lives of 2.51 and 3.13 days. Simple decontamination techniques showed 33 to 80 per cent reduction of residues in samples collected up to 10 days after treatment. The estimated RQ was less than one indicating the level of risk to the consumer is negligible.

A single quadrupole liquid chromatography-mass spectrometry (LC-MS) method was validated to determine the insecticide chlorantraniliprole residues in bitter gourd fruit, juice, and soil, according to the SANTE guidelines. A linear curve was obtained (R2 > 0.99) with LOD and LOQ at 0.003 mg kg-1 and 0.01 mg kg-1. The accuracy (87–102%) and precision (RSD <5%) of the method was found to be satisfactory. The  dissipation pattern of chlorantraniliprole 18.5% SC was studied by spraying twice at ten days intervals, at the recommended dose (X) (25 g a.i. ha-1), and double the recommended dose (2X) (50 g a.i. ha-1). The initial deposit on bitter gourd was 0.72 and 1.41 mg kg-1 and residues persisted up to 15 and 20 days with a half-life of 2.44 and 2.79 days at X and 2X doses, respectively. Simple decontamination techniques were found to reduce residues to the extent of 30 to 80 per cent. The reduction of chlorantraniliprole residues in bitter gourd juice was 40-50 per cent by different washing techniques. The estimated level of Risk quotient indicated (<1) chlorantraniliprole residues pose no dietary risk to consumers at the level detected.