| An effective extraction procedure based dispersive solid phase extraction was developed for the
extraction of different pesticides (dimethoate, imidacloprid, pirimicarb, carbaryl, fenitrothion, hexythiazox,
and phosalone) from milk samples. The analytes were determined by high performance liquid
chromatography-tandem mass spectrometry. In this method, an organic polymer (polystyrene) was
dissolved in a water-miscible organic solvent (tetrahydrofuran) and it was injected into the aqueous
phase obtained from milk sample after deprotonation. By this action the sorbent (polymer) was
precipitated and dispersed in the solution as tiny particles. By doing so, the pesticides were adsorbed
onto the sorbent. After that, the sorbent was separated by centrifugation and the adsorbed analytes were
eluted by tetrabutylammonium chloride: dichloroacetic acid deep eutectic solvent. After optimization,
the method validation was followed according to Food and Drug Administration and International
Research Council guidelines and the results showed that wide linear ranges (0.93e500 ng/mL) and low
limits of detection (0.09e0.27 ng/mL) and quantification (0.31e0.93 ng/mL) were obtained. Extraction recoveries and extraction and enrichment factors were in the ranges of 81e94% and 162e188, respectively.
Relative standard deviations were less than 9% for intrae (n ¼ 6) and intereday (n ¼ 6) precisions
at three concentration of 2, 5, and 25 ng mL1 of each analyte. The developed method was successfully
applied to twenty cow milk samples for determination of the pesticides. |