Validation of a ‘multi-residue’ analytical method for pesticideresidue analysis in fruits

A simple, rapid and reliable multi-residue analytical method was validated by carrying out pesticide residue determination in fruits such as mango and carambola. The analytes determined were α-endosulfan, β-endosulfan and endosulfan sulphate (organochlorine pesticides); chlorpyrifos, fenitrothion and prothiofos (organophosphorus pesticides); bifenthrin, cypermethrin, deltamethrin and fenpropathrin (synthetic pyrethroid pesticides). The method involved a process whereby the sample was chopped and homogenized, followed by blending with ethyl acetate using the Ultraturax blender. The extract was then subjected to a clean-up process in a PSA (Primary-Secondary Amines) powder prior to GC determination. The method was validated by conducting recovery studies where homogenised mango and carambola portions were fortified with known amounts of the pesticides, followed by extraction using the above mentioned method and subsequent residue quantification by GC. The recovery studies using 10 pesticides in the two crops showed acceptable range of recovery levels from 70 – 130% with the exception of deltamethrin (57.1% recovery at the spike rate of 0.1 mg/kg). The repeatability of the method was shown to be consistent with standard deviation of less than 20% for all the tested pesticides. The limits of quantification of pesticides observed were at a range of 0.02 – 0.5 mg/kg