Deep eutectic solvent-modified mixed iron hydroxide-silica: Application in magnetic solid-phase extraction for enrichment of organochlorine pesticides prior to GC-MS analysis.

A new type of magnetic material based on silica-coated mixed iron hydroxides functionalized with deep eutectic solvent was utilized for the magnetic solid-phase extraction of organochlorine pesticides prior to gas chromatography-mass spectrometry analysis. Choline chloride and phenol were selected as the hydrogen bond acceptor and donor, respectively, for preparing the deep eutectic solvent-modified magnetic surface. The modified surface possessed superior enrichment capability for organochlorine pesticides. Under optimal extraction conditions, viz., 10 mg sorbent, 5 mL sample solution, and 200 μL acetone (desorption solvent), linearity was obtained in the range 0.005-200 μg/L, with coefficients of determination greater than 0.997. The limits of detection and quantification were as low as 0.6-10 and 5-60 ng/L, respectively, whereas the enrichment factors were in the range of 31-100. The precisions evaluated in terms of the relative standard deviations of the intra- and inter-day experiments were <4.9 and 7.6%, respectively. The developed method was successfully applied for determining the organochlorine residues in agricultural products. Satisfactory recoveries in the range of 71.2-110.3% were obtained, with a relative standard deviation of <8.0%. The proposed material is a promising sorbent for the preconcentration of organochlorine residues.