Ionic Liquid-based Liquid-phase Microextraction Research Articles

Development of deep eutectic solvent-based microwave-assisted extraction combined with temperature controlled ionic liquid-based liquid phase microextraction for extraction of aflatoxins from cheese samples.

In this study, for the first time, a deep eutectic solvent-based microwave-assisted extraction was combined with ionic liquid-based temperature controlled liquid phase microextraction for the extraction of several aflatoxins from cheese samples. Briefly, the analytes are extracted from cheese sample (3g) into a mixture of 1.5mL choline chloride:ethylene glycol deep eutectic solvent and 3.5mL deionized water by exposing to microwave irradiations for 60 s at 180W. The liquid phase was taken and mixed with 55μL 1-hexyl-3-methylimidazolium hexafluorophosphate. By cooling the solution in the refrigerator centrifuge, a turbid state was obtained and the analytes were extracted into the ionic liquid droplets. The analytes were determined by high-performance liquid chromatography equipped with fluorescence detector. Low limits of detection (9-23ng kg-1 ) and quantification (30-77ng kg-1 ), high extraction recovery (66%-83%), acceptable enrichment factor (40-50), and good precision (relative standard deviations ≤ 5.2%) were obtained using the offered approach. These results reveal the high extraction capability of the method for determination of aflatoxins in the cheese samples. In this method, there was no need for organic solvents and it can be considered as green extraction method.

Vortex-Assisted Ionic Liquid-Based Liquid-Phase Microextraction: A Simple, Low-Cost, and Environmentally Friendly Method for Speciation of Antimony in Water

A sensitive method is proposed to determine antimony species using vortex-assisted ionic liquid-based liquid-phase microextraction and digital imaging colorimetry. SbIII forms a ternary complex with 2-(5-bromo-2-pyridylazo)-5-(diethylamino)phenol, ascorbic acid, and iodide in an acid medium. The acceptor phase consists of the ionic liquid 1-butyl-3-methylimidazole hexafluorophosphate, dispersed in the aqueous solution with a vortex stirrer. After centrifugation, SbIII was determined directly in the rich phase. SbV can also be measured by converting to reduced species. The method presented a limit of detection of 1.4 and 4.2 μg L−1 and an enrichment factor of 360. The precision (relative standard deviation) of the method is 7.0%. The procedure was applied to the speciation of antimony in river water and mineral water samples. Some results were compared with those obtained by electrothermal atomic absorption spectrometry (ET AAS). The method is an attractive alternative for determining antimony species, considering the aspects of green analytical chemistry.

High-throughput microscale extraction using ionic liquids and derivatives: A review.

Ionic liquids and derivatives-mainly polymeric ionic liquids and magnetic ionic liquids-have been extensively used in microscale extraction over the past few years. Current trends in analytical sample preparation gear toward linking microextraction approaches with high-throughput sample processing to comply with green analytical chemistry requirements. A variety of high sample throughput strategies that are coupled to both ionic-liquid-based solid-phase microextraction and ionic liquid-based liquid-phase microextraction are herein reported. The review is focused on microscale extraction methods that use (i) custom-made and dedicated extraction devices, (ii) parallel extraction, (iii) magnetic-based separation, and (iv) miniaturized systems employing semi-automatic or fully automatic flow injection methods, related micro/millifluidic devices, and robotic equipment.

Hybrid flow analyzer for automatic hollow-fiber-assisted ionic liquid-based liquid-phase microextraction with in-line membrane regeneration

The proof-of-concept of a new methodology for in-line hollow-fiber (HF)-assisted three-phase liquid-phase microextraction (LPME) allowing for handling of the feed and acceptor aqueous solutions and of minute volumes of the organic extracting phase in a programmable flow mode is reported in this paper. The flow analyzer fosters in-line anchoring of ionic-liquid-laden extracting solution (10 % (v/v) methyltrioctyl ammonium chloride in kerosene) in the pores of a single-strand microporous polypropylene HF, and regeneration of the liquid-phase membrane itself for each individual analysis cycle in a fully automated mode. Using hexavalent chromium as a model analyte and 1,5-diphenylcarbazide as a chromogenic probe in the acceptor solution, the flow-based HF-LPME hyphenated system was harnessed to the clean-up of troublesome samples (viz., domestic wastewater and soil leachates) with concomitant enrichment of target species. Distinct extraction modes and chemistries were assessed for enhanced Cr(VI) permeability. A single sample plug was subjected to a twofold backward-forward flow extraction so as to decrease the thickness of the boundary layer at the HF shell side for improved extraction efficiency. Under the optimized physicochemical variables, a limit of detection of 4.6 μg L(-1) Cr(VI), a dynamic linear range of up to 500 μg L(-1) and intermediate precision better than 10 % were obtained for a sample volume of 2.8 mL buffered at pH 4 and a volume of organic extractant of 120 μL, with an enrichment factor of ca. 11 for a sample residence time in the donor compartment of merely 4.5 min. Analyte recoveries in domestic wastewaters were ≥83 % using external calibration with relative standard deviations better than 14 %, thereby demonstrating the expedient clean-up of samples with elevated content of dissolved organic carbon. The automatic HF-LPME method was validated in terms of bias against the SRM 2701 (NIST soil) preceded by the EPA alkaline digestion method 3060A. No significant differences between Cr(VI) concentration as obtained with the automatic HF-LPME system (546 ± 57 mg kg(-1)) and the certified value (551.2 ± 17.2 mg kg(-1), expressed as mean ± combined uncertainty) were encountered at the 0.05 significance level.

Application of portable spectrometer for ultra trace metal analysis after ionic liquid based microextraction

In this work, a commercially available portable tungsten coil electrothermal atomic absorption spectrometer (W-coil ET-AAS) was applied and investigated. The portable AAS instrument was developed based on a W-coil atomizer and a charge coupled device detector, and has the characteristics of compactness and portability. In this research, ionic liquid based liquid phase microextraction (IL-LPME) was coupled with a portable AAS instrument to expand its application and improve its analytical performance. Ultra trace lead and copper were investigated as the target elements in the established coupling. The factors influencing both IL-LPME and the portable spectrometer were optimized. Under the optimal conditions, the limits of detection for lead and copper were 0.25 μg L−1 and 0.10 μg L−1, with sensitivity enhancement factors of 38 and 26, respectively. The relative standard deviation (RSD) for seven replicate measurements of 20 μg L−1 of lead was 4.9%, and 10 μg L−1 of copper was 3.4%. The recoveries for the spiked samples were in the acceptable range of 92.7–105%.

Ionic liquid-based liquid phase microextraction with direct injection for capillary electrophoresis

Liquid–liquid microextraction using the water immiscible ionic liquid, 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, EMIM NtfO 2, for the concentration and cleanup of basic compounds for analysis by CE has been investigated. Using an electrolyte comprising 1 mol/L alanine and 3 mol/L acetic acid, EMIM NtfO 2 could be directly injected into the capillary after liquid phase extraction. Using the basic dye chryisoidine, sensitivity enhancements approaching 1000-fold were obtained by mixing 20 μL of EMIM NtfO 2 with 1500 μL of aqueous sample, leaving only 5 μL of the undissolved ionic liquid which was used for injection into the CE. Lower more repeatable enhancement factors of 200-fold were obtained with slightly larger initial 25 μL volumes of EMIM NtfO 2 due to the larger residual volume of ionic liquid which made handling easier. This could be extended to basic pharmaceuticals, and the extraction of clozapine and its two active metabolites, nor-clozapine and clozapine-N-oxide, was demonstrated from urine with enrichment factors greater than 100 obtained. Handling of potentially more dangerous samples, such as serum, through in-vial extraction of clozapine and its metabolites and direct injection of the ionic liquid layer was also demonstrated with enhancements in sensitivity of 80. Limits of detection from 3 to 11 μg/L and 6 to 55 μg/L were obtained from urine and serum, respectively, which are sufficiently low to be useful for the determination of these pharmaceuticals clinically for therapeutic drug monitoring and for forensic toxicology.

Ionic liquid-based liquid-phase microextraction, a new sample enrichment procedure for liquid chromatography

Room temperature ionic liquids (RTILs) were used as extraction solvent in liquid-phase microextraction (LPME) coupled with liquid chromatography. Using 1-hexyl-3-methylimidazolium hexafluorophosphate ([C 6MIM][PF 6]) as extraction solvent, some parameters related to LPME of 4-nonylphenol (4-NP) and 4- tert-octylphenol (4- t-OP) were optimized. Although [C 6MIM][PF 6] can suspend a much larger volume of drop on the needle of the microsyringe than the conventional solvents such as 1-octanol and carbon tetrachloride, the method sensitivity was analyte dependent because of the different partition coefficients and the relatively large viscosity of [C 6MIM][PF 6]. The proposed procedure has a detection limit and enrichment factor of 0.3 μg l −1 and 163 for 4-NP, and 0.7 μg l −1 and 130 for 4- t-OP, respectively. Aqueous samples including tap water, river water, and effluent from sewage treatment plant were analyzed by the proposed method and the recoveries at 10 μg l −1 spiked level were in the range of 90–113%.