DABCOnium Ionic Liquid-Immobilized Silica Gel for Solid Phase Extraction of Phenoxyacetic Acid Herbicides in Water Samples

A novel sorbent (SiO2-(CH2)(3)-DABCO) for solid-phase extraction (SPE) was successfully prepared by chemical-bonding formation of diazabicyclo[2.2.2]octane ionic liquid onto silica gel. The structure of SiO2-(CH2)(3)-DABCO sorbent was characterized by FT-IR, TGA, SEM, EDX, and BET methods. Cartridges packed with the synthetic SiO2-(CH2)(3)-DABCO were used for the preconcentration of trace-level of phenoxyacetic acid herbicides in water samples for the first time. The factors influencing on the recovery were investigated, such as type of ion liquids, loading volume, eluents, elution volume, loading rate, and capacity. After the enrichment, the phenoxyacetic acid herbicides were analyzed by high-performance liquid chromatography with an ultraviolet detector. Four model phenoxyacetic acid herbicides, including 2-methyl-4-chlorophenoxyacetic acid (MCPA), 2,4,5-trichlorophenoxyacetic acid (2,4,5-T), fenoprop (2,4,5-TP) and haloxyfop were well retained and separated by this material with a recovery efficiency from 77 to 103 %. The SiO2-(CH2)(3)-DABCO demonstrated a good capacity corresponding to 0.56 mg of the analyte adsorbed per 100 mg of the material. The mixture of phosphate buffer (pH 7) : MeOH (50 : 50, v/v) was used to elute the analytes and provided the highest recovery with the standard deviations from 2.4 to 6.5. The high sensitivity with detection limits of 1.070-9.587 mu g/L can be achieved.