Ionic Liquid-based Microextraction Method Research Articles

Simultaneous determination of fat-soluble vitamins and carotenoids in human serum using a nanostructured ionic liquid based microextraction method

The determination of fat-soluble vitamins and carotenoids in human serum provides reliable information for diagnosing malnutrition and for establishing appropriate intervention programs. Due to the complex composition of the biological samples, the efficient sample preparation is the key to the analysis. We report here a surface active ionic liquid (SAIL)-based dispersive liquid-liquid microextraction (DLLME) method coupled with a high performance liquid chromatography (HPLC) to determine four fat-soluble vitamins and six carotenoids in human serum simultaneously. Liquid crystal structures were formed in the extract phase. And the enrichment factor of the analytes treated by DLLME was 4 to 26 times of the traditional LLE method except lycopene. The limit of determination for these compounds was determined to be between 0.002 and 0.076 µg/mL. The accuracy was validated by the standard addition method with recoveries ranging from 82.4 to 114.1%. The intra-day and inter-day relative standard deviations were 2.76–12.63% and 4.01–13.54%, respectively. The proposed DLLME coupled with the HPLC method was successfully applied in the determination of fat-soluble micronutrients in human serum.

An Ionic Liquid-based Microextraction Method for Ultra-High Preconcentration of Paraquat Traces in Water Samples Prior to HPLC Determination.

An ionic liquid (IL)-based microextraction method was developed for the preconcentration of paraquat traces in water samples prior to HPLC determination. On the basis of the relationship between the aqueous solubility and the extractability of known ILs, 1-ethyl-3-methylimidazolium bis(nonafluorobutanesulfonyl)amide ([EMIm][NNf2]) was selected as the extractant for paraquat. The distribution ratio of paraquat dication in the [EMIm][NNf2]/water biphasic system was theoretically estimated to be nearly 108 at its maximum level, indicating that [EMIm][NNf2] was suitable for the ultra-high preconcentration (a maximum of 106-fold concentration) of paraquat with a quantitative recovery (more than 99%). The extraction procedure could be performed easily and quickly following the in situ solvent formation microextraction technique, and the paraquat traces in the IL phase could be determined by hydrophilic interaction chromatography with good detection limits and linearity ranges (0.16 and 1 - 50 ng mL-1 for paraquat, respectively). The combined method was successfully applied to four real environmental water samples spiked with paraquat and its analog, diquat at 5.0 ng mL-1.

A simple and sensitive vortex-assisted ionic liquid-dispersive microextraction and spectrophotometric determination of selenium in food samples

In the present study, a novel and eco-friendly vortex-assisted ionic liquid-based microextraction method was developed for the determination of selenium in food. The microextraction method is based on the liberation of iodine in the presence of selenium; the liberated iodine reacts with I− to form I3−. Anionic I3− reacts with cationic crystal violet dye, and the product is extracted into 1-hexyl-3-methylimidazolium hexafluorophosphate phase in the presence of Triton X-114. The proposed method is linear in the range of 2.0–70µgL−1 and has a detection limit of 9.8×10−2µgL−1. Relative standard deviations were 3.67% and 2.89% for the five replicate measurements of 14 and 35µgL−1 Se(IV), respectively. The proposed method was successfully applied to different food samples (NIST SRM 2976 mussel tissue, pepper, ginger, wheat flour, red lentil, traditional soup, cornflour, cornstarch, and garlic) after microwave digestion.

An ionic liquid-based microextraction method for highly selective and sensitive trace determination of nickel in environmental and biological samples

Nickel was complexed with BTAHQ at pH 4.0. The IL-DLLME procedure was performed by using a few mL of [C6mim][PF6] as the extractant while methanol was the disperser solvent. The Ni-enriched RTIL phase was solubilized in methanol and the absorbance atλmax682 was directly measured against a reagent blank similarly prepared.

An ionic liquid-based microextraction method for the determination of Cu and Ni in high-salinity produced water from offshore petroleum exploration by GF AAS

This work reports the development of a novel method for the ionic-liquid microextraction and determination of Cu and Ni in high-salinity produced water by Graphite Furnace Atomic Absorption Spectrometry (GF AAS).

Ultrasound-assisted ionic liquid-based microextraction combined with least squares support vector machines regression for the simultaneous determination of aluminum, gallium, and indium in water and coal samples

A new simple and rapid ultrasound-assisted ionic liquid-based microextraction method was applied to preconcentrate aluminum(III), gallium(III), and indium(III) ions from water samples as a prior step to their simultaneous spectrophotometric determination using least squares support vector machines regression. In the novel procedure, 1-hexyl-3-methylimidazolium hexafluorophosphate [C(6)MIM][PF(6)] was dispersed into the aqueous sample solution as fine droplets by ultrasonication, and the analytes were extracted into the ionic liquid phase after complexation with 1,2,5,8-tetrahydroxy anthraquinone (quinalizarine). After centrifuging, the fine droplets of extractant phase were settled to the bottom of the conical-bottom glass centrifuge tube. The detection limits for Al(III), Ga(III), and In(III) were 1.70, 2.02, and 2.06 ng mL(-1), respectively. The precision of the method, evaluated as the relative standard deviation obtained by analyzing a series of ten replicates, was below 3.2% for all elements. The method was successfully applied for the determination of Al(III), Ga(III), and In(III) in real samples.

Highly selective ionic liquid-based microextraction method for sensitive trace cobalt determination in environmental and biological samples

A simple and rapid dispersive liquid–liquid microextraction procedure based on an ionic liquid (IL-DLLME) was developed for selective determination of cobalt (Co) with electrothermal atomic absorption spectrometry (ETAAS) detection. Cobalt was initially complexed with 1-nitroso-2-naphtol (1N2N) reagent at pH 4.0. The IL-DLLME procedure was then performed by using a few microliters of the room temperature ionic liquid (RTIL) 1-hexyl-3-methylimidazolium hexafluorophosphate [C 6mim][PF 6] as extractant while methanol was the dispersant solvent. After microextraction procedure, the Co-enriched RTIL phase was solubilized in methanol and directly injected into the graphite furnace. The effect of several variables on Co–1N2N complex formation, extraction with the dispersed RTIL phase, and analyte detection with ETAAS, was carefully studied in this work. An enrichment factor of 120 was obtained with only 6 mL of sample solution and under optimal experimental conditions. The resultant limit of detection (LOD) was 3.8 ng L −1, while the relative standard deviation (RSD) was 3.4% (at 1 μg L −1 Co level and n = 10), calculated from the peak height of absorbance signals. The accuracy of the proposed methodology was tested by analysis of a certified reference material. The method was successfully applied for the determination of Co in environmental and biological samples.

New industrial uses for farm crops

In the present study, a novel and eco-friendly vortex-assisted ionic liquid-based microextraction method was developed for the determination of selenium in food. The microextraction method is based on the liberation of iodine in the presence of selenium; the liberated iodine reacts with I− to form I3−. Anionic I3− reacts with cationic crystal violet dye, and the product is extracted into 1-hexyl-3-methylimidazolium hexafluorophosphate phase in the presence of Triton X-114. The proposed method is linear in the range of 2.0–70 µg L−1 and has a detection limit of 9.8 × 10−2 µg L−1. Relative standard deviations were 3.67% and 2.89% for the five replicate measurements of 14 and 35 µg L−1 Se(IV), respectively. The proposed method was successfully applied to different food samples (NIST SRM 2976 mussel tissue, pepper, ginger, wheat flour, red lentil, traditional soup, cornflour, cornstarch, and garlic) after microwave digestion.