Salt De-Emulsification Dispersive Liquid-Liquid Microextraction and Back-Extraction Combined with Sweeping Micellar Electrokinetic Capillary Chromatography for Detection of Triazine Herbicides in Honey

Abstract

A rapid, simple, and sensitive method has been developed for the analysis of triazine herbicides in honey samples by using salt de-emulsification dispersive liquid-liquid microextraction and back-extraction (SD-DLLME-BE) coupled with sweeping in micellar electrokinetic chromatography (MEKC). In the newly developed method, chloroform can be generated by the reaction of chloral hydrate and sodium hydroxide, and the chloroform droplets dispersed into bulk aqueous solution can be swiftly carried to the bottom of the centrifuge tube with the addition of calcium chloride. Then, back-extraction was utilized to extract the analytes into an aqueous solution prior to capillary electrophoresis (CE) analysis. The advantages of the new in situ DLLME lie in dispersive solvent-free and no centrifugation operation compared with the conventional DLLME. Several important parameters influencing the preconcentration and extraction efficiency of SD-DLLME-BE such as sodium dodecyl sulfate (SDS) concentration, pH, chloral hydrate and sodium hydroxide content, extraction time, and calcium chloride content were optimized. Under the optimized conditions, the enrichment factors were achieved in the range from 459 to 636. The proposed method provided a good linearity, low limits of detection (8.56 ng/mL), and good repeatability of the extractions (relative standard deviations (RSDs) below 8.8 %, n = 6). Honey samples were analyzed by the proposed method, and obtained results indicated that the proposed method provides acceptable recoveries and precisions.