A ternary deep eutectic solvent-modified magnetic mixed iron hydroxide@MIL-101(Cr)-NH composite as a sorbent in magnetic solid phase extraction of organochlorine pesticides prior to GC-MS.

A green solvent of ternary deep eutectic solvent (menthol-thymol-dodecanoic acid) was prepared and used as a functional reagent to modify a magnetic mixed iron hydroxide@MIL-101(Cr)-NH composite. The proposed sorbent (MIH@MIL-101(Cr)-NH-TDES) was applied in magnetic solid phase extraction (MSPE) for the enrichment of organochlorine pesticides. The analytes were quantitively analyzed by GC-MS. The relationships of experimental parameters for preparing the proposed sorbent and the MSPE method were studied through a Box-Behnken design and a central composite design, respectively. Their optimized conditions were investigated using response surface methodology. Application of the MIH@MIL-101(Cr)-NH-TDES sorbent in MSPE successfully enhanced the sensitivity of GC-MS analysis, giving enrichment factors in the range of 56-168. The MSPE/GC-MS method was developed using MIH@MIL-101(Cr)-NH-TDES as a sorbent and was successfully employed for the preconcentration/determination of organochlorine residues in honey and tea samples. The satisfactory detection limits were in the ranges of 0.07-0.80 ng g and 0.7-8.5 ng g for honey and tea samples, respectively. Acceptable recoveries were obtained in the ranges of 81.7-107.3% and 85.4-109.3% for the spiked honey and tea samples, respectively, with RSDs lower than 10.0%.