Interaction of Pesticides with Clean-up Agents during QuEChERS Dispersive-SPE Clean-up

A method was developed using liquid chromatography tandem mass spectroscopy for the identification and quantification of multi residues of pesticides. The present study is first of this kind, destined purely to understand the interaction between the clean-up agents with 103 pesticides. The QuEChERS clean-up, employing most commonly used clean-up agents like anhyd.MgSO₄, PSA, C-18 and GCB in twelve combinations, was performed to assess their adsorption behavior with the pesticides. Recovery studies at 1μg∙mL⁻¹ showed that anhyd.MgSO₄ gave acceptable recovery for 100 pesticides (97.08%) in treatment T1. The PSA adsorbed some polar and acidic pesticides onto it and gave acceptable recovery for < 90% pesticides in T2 to T5 and C-18 with anhyd.MgSO₄ & varying amount of PSA (T6, T7) gave a lower, but acceptable recovery of 83.49% pesticides. GCB with anhyd.MgSO₄ & varying amount of PSA (T8, T9), adsorbed some planar pesticides like carbendazim, tricyclazole and gave a lower, but acceptable recovery for 74.75 – 77.66% pesticides. In T10 to T12, when all the adsorbents were used, adsorption of polar, acidic and planar pesticides (25.24%) was observed while rest of the pesticides (74.75%) gave acceptable recovery. The method also satisfied the single laboratory validation criteria for linearity, specificity, accuracy and precision.