This study reports the development and validation of a fast, efficient, and cost effective multiresidue method for determination of 14 lipophilic and analytically problematic pesticides in crude cottonseed oil. Crude cottonseed oil contains high amount of saturated fatty acid and pigments that are problematic in pesticide residues analysis. Modified liquid-liquid partitioning with acetonitrile and n-hexane in 10:1 (v/v) ratio was used to extract pesticides. For clean-up, different combinations of sorbents were used and optimum recovery and minimal matrix effect were obtained with the combination of activated charcoal and primary secondary amine for the selected pesticides. For majority of the analyzed pesticides, the method validation parameters i.e. percent recovery (71.6-140.0%), precision (%RSD 9.7 to 33.0), LOD (0.041 to 0.096 µg/g), LOQ (0.125-0.264 µg/g), linearity (0.998-0.999) and matrix effect (±27%) were in acceptable range as prescribed by EU SANTE guidelines. Two-way Analysis of variance of inter-labs comparison study revealed non-significant interaction effects for most of studied pesticides indicating that the current method can be confidently used in labs for monitoring of these pesticides in crude cottonseed oil.

Rashid Muhammad, Karam Ahad, Muhammad Ishtiaq, Farrakh Mehboob