Ionic Liquid-based Microextraction Research Articles

Development of an ionic liquid-based microextraction system (ILBME) for sensitive spectrophotometric analysis of neodymium(III) ions in environmental samples

ABSTRACT Introducing a precise, sensitive and simple system for determining neodymium(III) ions in aquatic samples could enhance the capabilities of routine instruments, particularly in terms of detection limits. Coupling a powerful preconcentration system, such as ionic liquid-based microextraction (ILBME), with a spectrophotometer can successfully achieve this goal. A sensitive and simple microextraction method based on a task-specific ionic liquid, designated [PDmim][Cl2], is described, in which the imidazolium-based ionic liquid served dual roles as both the chelating agent and the extraction phase. The ionic liquid was synthesized and characterized before being applied in microextraction procedure. The optimized microextraction results indicate that neodymium concentrations up to 5.10 µg L−1 can be successfully determined. The method characteristics, including the limit of detection (LOD), limit of quantification (LOQ), intra-day and inter-day relative standard deviations (RSDs), preconcentration factor (PF), enrichment factor (EF) and linear dynamic range (LDR), were found to be 1.53 µg L−1, 5.10 µg L−1, 3.83%, 4.44%, 123, 111.1 and 5.0–125.0 µg L−1, respectively. For method validation, the standard addition method using standard reference material (SRM) was employed, and the recovery range from real samples analyses was between 99.3% and 101.0%.

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.

Experimental Design of Magnetic Ionic Liquid-Based Ultrasound-Assisted Liquid Phases Microextraction for the Determination of 5-Hmf in Honey Samples Collected from Different Botanical and Geographical Origins in Turkey

Experimental Design of Magnetic Ionic Liquid-Based Ultrasound-Assisted Liquid Phases Microextraction for the Determination of 5-Hmf in Honey Samples Collected from Different Botanical and Geographical Origins in Turkey

Assessment of environmental pollutants at trace levels using ionic liquids-based liquid-phase microextraction.

Sample preparation is the crucial and most challenging part of analytical chemistry for the speciation of environmental pollutants' traces. Along with the development of the sample preparation methods, the ionic liquid-based microextraction technique plays an important role. Due to the unequivocally unique "green" characteristic of ionic liquids (ILs), they owe their tunable properties, such as highly selective and high reaction efficiency, reusability, and good thermal stability, to present advancements in the sample preparation process. The ionic liquid-based microextraction techniques miniaturize the sample preparation process. Liquid phase microextraction intermediate solvents, desorption solvent extractants, and mediators have been used. They are quoting the benefits and limitations of each method. A few essential sample preparation methods covered the microextraction technique. In this context, miniaturized microextraction methods have been developed. They are generally used for their unlimited positive features, including easy, simple, and environmentally friendly; they also extract inorganic and organic species with low-cost instrumentation. This review advances the sample preparation process using ILs-based liquid phase microextraction as an intermediate solvent, extractant desorption, and mediator solvents.

Temperature-Sensitive Ionic Liquid-Based Dispersive Microextraction for Removal of Industrial Dyes in Water

Temperature-Sensitive Ionic Liquid-Based Dispersive Microextraction for Removal of Industrial Dyes in Water

Response surface methodology based on central composite design for optimizing temperature-controlled ionic liquid-based microextraction for the determination of histamine residual in canned fish products

A rapid and simple analytical procedure for the determination of histamine in canned fish products using temperature-controlled ionic liquid-based microextraction (TC-IL-ME) mated to chemometric tool and coupled to spectrophotometer was developed. The variables of interest in the TC-IL-ME method, such as volume of disperser solvent, pH, tartarazine (as ligand) amount, extraction temperature as well as ionic liquid amount were optimized by using a response surface methodology (RSM) based on central composite design (CCD). The ionic liquid, 1-hexyl-3- methylimidazolium tetrafluoroborate [Hmim] [BF4] was used as an extraction solvent, while acetone was used as a disperser solvent. The optimum TC-IL-ME conditions were found as pH 6.0 of sample solution, 60.7 μmol L−1 of tartarazine amount, 765 μL of acetone volume, 0.5 mg of [Hmim] [BF4] amount and 36 °C of extraction temperature. Interactions between tartrazine and histamine were also investigated using computational chemistry approach. Under the selected conditions, the calibration curve was linear in the range of 2–400 ng mL−1. The repeatability and reproducibility (RSD%) were ranged between 2.5–3.7 % and 2.8–4.1 %, respectively and limit of detection (LOD) was calculated to be 0.65 ng mL−1. The accuracy of the recommended method was confirmed by the analysis of reference material (TET040RM-Histamine in canned fish), the spike test showed recoveries between 92.4 % and 104.9 %. Finally, the recommended method was successfully applied to canned fish products, the concentration of histamine ranged from 62.8–287.5 μg g−1.

Spectrophotometric determination of aflatoxin B1 in food sample: Chemometric optimization and theoretical supports for reaction mechanisms and binding regions

A green, simple, and cheap analytical approach for extraction, preconcentration, and determination of aflatoxin B1 (AFB1) in food samples based on vortex-assisted room temperature ionic liquid-based microextraction (VA-RTIL-ME) was presented. Important parameters including pH, metal amount, ligand amount and vortex time were optimized by using Box–Behnken design. At pH = 5.6, a ternary complex between Zn(II), fluorescein and AFB1 was formed, and extracted into the fine droplets of Tri-n-butyl phosphate (room temperature ionic liquid, extraction solvent) which were dispersed with a vortex (disperser solvent) into the extraction solution. Quantum chemical parameters and tools are widely used to predict the reaction mechanisms of interactions and binding regions of molecules. Via calculated quantum chemical parameters and energy calculations, reactions mechanisms and binding regions for studied molecules were highlighted. Under optimized conditions, linear range, limit detection, enrichment factor were 3–500 ng mL-1, 0.9 ng mL-1 and 140, respectively. Detailed validation studies (accuracy, precision, measurement uncertainty, selectivity, robustness..etc.) were performed under optimum experimental conditions. The good recoveries (93.9–104.3%) and low relative standard deviation (RSD%, 1.5-3.0%) were a good remark of the proposed method. For the reliability of analytical results, the results obtained with the developed method were compared with the standard ELISA test for AFB1. The developed method was successfully applied to the extraction and determination of AFB1 in food samples.

Flame atomic absorption spectrometric determination of total chromium and cadmium in bean samples after ultrasonic-assisted microextraction using ionic liquid Aliquat-336

A new and rapid microextraction approach termed as ultrasonic-assisted ionic liquid-based microextraction (UA-ILME) was developed using ionic liquid Aliquat-336 as extraction solvent for the extraction of chromium and cadmium in bean samples collected from different regions in Turkey. The total amounts of analytes in the samples were measured by flame atomic absorption spectrophotometry. The basis of the extraction step is based on the complexation of Cr(III) and Cd(II) with diethyldithiocarbamate at pH 4.0. The hydrophobic ternary complexes containing analytes were then rapidly extracted from the sample solution to the ionic phase under the ultrasonic effect using tricaprylylmethylammonium chloride (Aliquat-336). Some experimental variables (pH, ligand amount, extraction solvent volume, ultrasound time, extraction temperature and sample volume) were optimized in detail. Following the optimization steps, the limits of detection (LODs, 3Sblank/m) for Cr(III) and Cd(II) were calculated as 0.45 ng mL−1 with linear range of 1.5–380 ng mL−1 and 0.25 ng mL−1 with linear range of 0.8–220 ng mL−1, respectively. Enrichment factors and average recoveries were ranged from 125.8–96.4 to 92.7–106.5%, respectively. The accuracy and precision of the method were validated by analyzing a certified reference material and spiked recovery tests. The UA-ILME method was successfully applied to the determination of Cd and Cr in the samples, highlighting that the matrix ions under consideration do not affect the extraction and determination steps.

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.

Ultrasonically Dispersed Ionic Liquid-Based Microextraction of Lead in Biological Samples of Malnourished Children Prior to Analysis by Flame Atomic Absorption Spectrometry.

In the present study, a simple ultrasonically dispersed modified liquid-phase microextraction method was developed for the extraction of lead (Pb) from blood and scalp hair samples of malnourished children (MNC). The complexation of Pb was executed by means of the complexing agent, ammonium pyrrolidinedithiocarbamate (APDC), whereas extraction was carried out through the ionic liquid (IL), 1-butyl-3-methylimidazolium hexafluorophosphate. Ultrasound energy was used for the dispersion and extraction of the metal complex into an IL because it enhances the extraction of the metal complex into infinite IL drops at a temperature range of 40-80°C for 1-5 min. After sonication, the enriched analyte phase was separated by centrifugation. Nitric acid (HNO3; 0.5-2 mol/L) was added to the IL-enriched phase to back-extract the analyte into the acidic aqueous phase and analyzed by flame atomic absorption spectrometry. Various experimental parameters that affect the efficiency of the proposed method, such as volume of IL, concentration of the complexing agent, pH, ultrasonication time and temperature, and concentration of HNO3, were optimized. The enhancement factor was calculated as 70. The LOD for Pb ions was found to be 0.19 μg/L, with an RSD of <5%. Accuracy was ensured by applying the procedure to a certified reference material for whole blood and scalp hair. The developed procedure was successfully applied for the analysis of the concentration of Pb ion in whole-blood and scalp hair samples of MNC from different areas of Sindh, Pakistan. The concentration of Pb among MNC was 2-fold higher than the referent.

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.

Application of ionic liquid-based ultrasonic-assisted microextraction coupled with HPLC for determination of citalopram and nortriptyline in human plasma

ABSTRACTIn this paper, an effective and environmentally friendly method of ultrasound-assisted ionic liquid-based dispersive liquid–liquid microextraction (UA-IL-DLLME) combined with high-performance liquid chromatography (HPLC)–photodiode array detector was applied for extraction and determination of two antidepressant drugs citalopram hydrobromide and nortriptyline hydrochloride from human plasma samples. Several important parameters affect the steps and efficiency of extraction, some of which are sample solution’s pH, type and volume of ionic liquid, ultrasonic time, centrifuging time and rate, and the ionic strength of solution. Optimum conditions were obtained at pH = 11, 1-octyl-3-methyl imidazolium hexafluorophosphate for ionic liquid, 55 µL for ionic liquid volume, 4 min for ultrasonic time, 5 min and 3,500 rpm for centrifuging time and rotation’s speed, due to ionic strength by the addition of NaCl 1%. Under optimized conditions, the linearity was obtained in the range of 0.02–2,000 µg/L, with correlation coefficients higher than 0.995. The limits of detection were 10 µg/L for citalopram and 6 µg/L for nortriptyline. Preconcentration factors were 920 for citalopram and 800 for nortriptyline. The present method of UA-IL-DLLME combined with HPLC was successfully used for the determination of citalopram and nortriptyline drugs in real samples of human plasma.

Reflection scanometry as a new detection technique in temperature-controlled ionic liquid-based dispersive liquid phase microextraction

Coupling temperature-controlled ionic liquid-based dispersive liquid phase microextraction with reflection scanometry as a new detection technique for colored liquid solutions.

Estimation of lead in biological samples of oral cancer patients chewing smokeless tobacco products by ionic liquid-based microextraction in a single syringe system.

Several studies have reported that the chewing habit of smokeless tobacco (SLT) has been associated with oral cancer. The aim of the present study was to evaluate the trace levels of lead (Pb) in biological samples (blood, scalp hair) of oral cancer patients and referents of the same age group (range 30-60 years). As the concentrations of Pb are very low in biological samples, so a simple and efficient ionic liquid-based microextraction in a single syringe system has been developed, as a prior step to determination by flame atomic absorption spectrometry. In this procedure, the hydrophobic chelates of Pb with ammonium pyrrolidinedithiocarbamate (APDC) were extracted into fine droplets of 1-butyl-3-methylimidazolium hexafluorophosphate [C4MIM][PF6] within a syringe while using Triton X-114 as a dispersant. Factors influencing the microextraction efficiency and determination, such as pH of the sample, volume of [C4MIM][PF6] and Triton X-114, ligand concentration, and incubation time, were studied. To validate the proposed method, certified reference materials were analyzed and the results of Pb(2+) were in good agreement with certified values. At optimum experimental values of significant variables, detection limit and enhancement factor were found to be 0.412 μg/L and 80, respectively. The coexisting ions showed no obvious negative outcome on Pb preconcentration. The proposed method was applied satisfactorily for the preconcentration of Pb(2+) in acid-digested SLT and biological samples of the study population. It was observed that oral cancer patients who consumed different SLT products have 2-3-fold higher levels of Pb in scalp hair and blood samples as compared to healthy referents (p < 0.001). While 31.4-50.8% higher levels of Pb were observed in referents chewing different SLT products as compared to nonconsumers (p < 0.01).

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).

Ultrasonic assisted ionic liquid based microextraction for preconcentration and determination of aluminum in drinking water, blood and urine samples of kidney failure patients: Multivariate study

We have developed a simple ultrasonic-assisted ionic liquid-based microextraction (US-ILME) method for trace levels of aluminum (Al3+), in water, blood, and urine samples, followed by atomic absorption spectrometry with a nitrous oxide–acetylene flame. An ionic liquid, 1-hexylpyridinium hexafluorophosphate [Hpy][PF6], was used as the extraction solvent, and 8-hydroxyquinoline (oxine), was used as the Al3+ chelating agent. A multivariate strategy was employed to evaluate five factors/variables (concentration of the chelating agent, pH, amount of ionic liquid, sonication time and centrifugation time) at once, whereas a central composite design was used to find the optimum values of the significant variables. The multivariate strategy was used to estimate the optimum values of experimental factors that influence the efficiency of US-ILME. Under the optimum experimental conditions, the limit of detection (3 s) and enrichment factor were 0.66 μg L−1 and 113, respectively. The relative standard deviation (RSD) for six replicate determinations of 10 μg L−1 of Al3+ was 1.7%. The method was validated by the analysis of certified reference materials and applied successfully to the determination of Al3+ in different types of drinking water, and in blood and urine samples of kidney failure patients. The data indicated that the levels of Al3+ were significantly higher in kidney failure patients compared with healthy referents (p < 0.01).

Ionic liquid-based hollow fiber liquid-phase microextraction for the determination of trace lead (II) in environmental water and tea drinks samples by graphite furnace atomic absorption spectrometry

A three-phase hollow fiber liquid-phase microextraction (HF-LPME) was used to determine the trace amounts of Lead (II) in environmental water and tea drinks. In this approach, green solvent ionic liquid 1-hexyl-3-methylimidazolium hexafluorophosphate ([HMIM]PF6) was used as membrane carrier that dissolved in hollow fiber pores. 1-(2-Pyridylazo)-2-naphthol (PAN) was placed in aqueous solution to form hydrophobic complex with Pb(II). Ethylene diamine tetraacetic acid (EDTA) was used as stripping agent that it can form water-soluble complex with Pb(II). After extraction, the acceptor solution was directly injected into the graphite furnace atomic absorption spectrometry (GF-AAS) for analysis. Some important parameters that influence the extraction efficiency were investigated, such as PAN concentration, pH, EDTA concentration, stirring rate, extraction time, and interfering metal ions. Under the optimized conditions, an enrichment factor (EF) of 210 and a limit of detection (LOD) of 0.004 ng mL−1 were obtained. The calibration curve was linear in the range of 0.05–0.5 ng mL−1 (R = 0.999). The relative standard deviation (RSD) at the 0.12 ng mL−1 Pb(II) level is 4.5 % (n = 6). The proposed method was successfully applied to determination of Pb(II) in environmental water and tea drinks samples with satisfactory recoveries in the range of 94–105 %.

Determination of four pesticides in soil by homogeneous ionic liquid-based microextraction coupled with high-performance liquid chromatography

Homogeneous ionic liquid microextraction was developed for the simultaneceus extraction of dimethomorph, mefenacet, isoprothiolane and oxadiazon from soil. 1-Butyl-3-methylimidazolium tetrafluoroborate was used as extraction solvent, and ammonium hexafluorophosphate was used as ion-pairing agent. High-performance liquid chromatography(HPLC) was employed for separation and determination of the analytes. The calibration curves show good linear relationship(r>0.9988). The recoveries are between 74.2% and 97.9% with relative standard deviations(RSDs) lower than 5.97%. The present method is free of volatile organic solvents, and expenditures of sample, extraction time and solvent are lower, compared with ultrasonic and Soxhlet extraction. There was no obvious difference in the extraction recoveries of pesticides obtained by the three extraction methods.

Ionic Liquid-Based Ultrasound-Assisted Emulsification Microextraction Coupled with HPLC for Simultaneous Determination of Glucocorticoids and Sex Hormones in Cosmetics

An effective and environmentally friendly method based on ionic liquid-based ultrasound-assisted emulsification microextraction(IL-USAEME) and high performance liquid chromatography (HPLC) has been developed for the determination of nine hormones including three glucocorticoids, one androgen and five progestogens in cosmetics. Several factors that affect the extraction efficiency, such as the kinds and volume of ionic liquid, salt concentration, ultrasonic power and time, and centrifugation time were investigated and optimized. Under the optimum extraction condition, the recoveries of analytes ranged from 85.97% to 108.84% except prednisolone (62.30%). The intraday and interday precision was below 2.51% and 3.30%, respectively.