Dissipation of quinalphos in kinnow mandarin fruits under subtropical conditions of Punjab, India.

Quinalphos residues were studied separately in the pulp and rind of kinnow mandarin fruits by following a standardized methodology and estimated on gas liquid chromatograph (GC) by employing nitrogen phosphorus detector. Following application of quanilphos (Ekalux 25EC) at 10.0 and 20.0 mL per tree (per 5 L of water) on kinnow mandarin fruits at both these dosages were found to be 0.05 and 0.16 mg/kg, respectively. These initial deposits were found to be less than its maximum residue limit (MRL) of 0.25 mg/kg. The corresponding values in the rind were found to be 0.65 and 1.64 mg/kg, respectively. These residue levels in the rind dissipated below the MRL in 5 and 15 days, respectively. The half-life value for quanilphos in the rind at single and double dosages were found to be 3.2 and 4.0 days, respectively. Low dissipation rate of quanilphos in the rind may be attributed to the fibrous nature of the peel where the insecticide can be adsorbed, high moisture content and oil based nature of the rind. The results clearly show that quanilphos does not penetrate into the pulp of the kinnow mandarin and the fruit is safe for consumption even after one day of the application at both these dosages.