| In this study, a pH-induced solidification of floating organic droplet homogeneous liquid–liquid
microextraction procedure using deep eutectic solvent decomposition was developed for the extraction
of five pyrethroid insecticides from milk samples prior to their analysis by using a gas chromatographyflame ionization detector. To reach this goal, the sample was transferred into a glass test tube and its
proteins were precipitated with trichloroacetic acid. After centrifugation, the supernatant phase was
transferred into another test tube and a few microliters of menthol: p-aminophenol deep eutectic
solvent were dissolved in the solution and shaken to obtain a homogeneous solution. Then a few
microliters of ammonia solution were added to the solution and the mixture was sonicated to break
down the homogeneous solution. By doing so, the deep eutectic solvent was decomposed and menthol
was formed throughout the solution as tiny droplets. In the following, the tube was transferred into an
ice bath to solidify the extraction solvent on the solution surface. The collected phase was removed and
melted at room temperature and an aliquot of it was analyzed by using a determination system. The
validation outcomes confirmed that the method provides high extraction recoveries (72–84%) and high
enrichment factors (257–299) with acceptable repeatability (relative standard deviations #6.4%). Low
limits of detection (1.1–2.4 ng mL1
) and quantification (3.6–8.1 ng mL1
) were obtained using this
approach. Finally, several milk samples were analyzed and deltamethrin was successfully determined in
some samples. |