Cold-induced Aggregation Microextraction Research Articles

Preconcentration and Determination of Tungsten Using Cold-Induced Aggregation Microextraction Technique Via Ionic Liquid in Environmental and Biological Samples

Spectrophotometry in combination with cold induced aggregation microextraction was used to preconcentrate and determine tungsten in environmental and biological samples. The preconcentration and extraction of tungsten was performed in the presence of 5-(2′,4′-dimethylphenylazo)-6-hydroxypyrimidine-2,4-dione (DMPAHPD) as complexing agent. In the present procedure, sodium hexafluorophosphate (NaPF6) was transferred to the sample solution containing minimum amounts of 1-hexyl-3-methylimidazolium hexafluorophosphate [Hmim][PF6] as extraction solvent. The preconcentration and extraction efficiency were affected and optimized by parameters as amount of ionic liquid, ionic strength pH, and temperature. The applicability was evaluated to detect trace amount of tungsten in various types of environmental and biological samples. The calibration curve was linear in the concentration range 2.5-80 ng mL-1 with correlation coefficient (r2) of 0.9994 under the optimum experimental conditions. The relative standard deviation (RSD) was 1.73 % for 40 ng mL-1 (n = 10) tungsten. The detection limit (LOD) of 0.8 ng mL-1 and enhancement factor of 300 were obtained.

A preconcentration method for analysis of neonicotinoids in honey samples by ionic liquid-based cold-induced aggregation microextraction

A preconcentration approach based on ionic liquid-based cold-induced aggregation microextraction for determination of neonicotinoid insecticide residues in honey samples before high-performance liquid chromatographic analysis has been developed. Room temperature ionic liquid [C4MIM][PF6] (extraction solvent) and SDS (emulsifier) was used for extraction of the target analytes. The parameters affecting the extraction efficiency were optimized. The optimum microextraction conditions were 200µL room temperature ionic liquids [C4MIM][PF6] containing 0.05molL−1 SDS, 0.75g sodium carbonate, vortex agitation speed of 1800rpm for 30s and centrifugation at 3500rpm for 10min. Under optimum conditions, the high enrichment factors of 200 could be obtained, leading to low limit of detection (0.01µgL−1 for all analytes) with the relative standard deviations lower than 2.68% and 5.38% for retention time and peak area, respectively. Good recoveries for the spiked target neonicotinoids at three different concentrations of honey samples were obtained in 86–100% and relative standard deviations were lower than 8.1%. The results demonstrated that the proposed method can be used as an alternative powerful method for the simultaneous determination of the studied insecticides in real honey samples.

Determination of cobalt in high-salinity reverse osmosis concentrates using flame atomic absorption spectrometry after cold-induced aggregation microextraction

Cold-induced aggregation microextraction (CIAME) is a robust procedure for high-salinity reverse osmosis concentrates.

Determination of nickel using cold-induced aggregation microextraction based on ionic liquid followed by flame atomic absorption spectrometry

Cold-induced aggregation microextraction (CIAME) combined with flame atomic absorption spectrometry (FAAS) was applied to preconcentration and determination of nickel(II) ions in natural water samples. The proposed method used 1-hexyl-3-methylimidazolium hexafluorophosphate ([Hmim][PF6]) as the extraction solvent and 1-(2-thiazolylazo)-2-naphthol (TAN) as the complexing agent. The extraction solvent was dissolved in the sample solution at 45°C. After dissolving, the solution was cooled in the ice bath and a cloudy solution of IL fine droplets was formed due to the decrease of IL solubility. After centrifugation, the fine droplets of extractant phase were settled at the bottom of the conical-bottom centrifuge tube. Analysis was carried out by a FAAS. Several important parameters influencing the CIAME extraction efficiency such as pH, complexing agent concentration, extraction solvent volume, salt effect, solution temperature, extraction time, centrifugation time and heating time were investigated and optimized. Under the optimum conditions, the limit of detection (LOD) was 0.8 ng/mL, and the relative standard deviation (RSD) was 3.4% for 50 ng/mL of nickel. The performance of the method was evaluated for extraction and determination of nickel in tap, mineral and seawater samples, and satisfactory results were obtained.

Application of cold-induced aggregation microextraction as a fast, simple, and organic solvent-free method for the separation and preconcentration of Se(IV) in rice and various water samples

The developed method is based on cold-induced aggregation microextraction of Se(IV) using the 1-butyl-3-methylimidazolium hexafluorophosphate ionic liquid as an extractant followed by spectrophotometry determination. The extraction of Se(IV) was performed in the presence of dithizone as the complexing agent. In this method, a very small amount of 1-butyl-3-methylimidazolium hexafluorophosphate was added to the sample solution containing Se-dithizone complex. Then, the solution was kept in a thermostated bath at 50°C for 4min. Subsequently, the solution was cooled in an ice bath and a cloudy solution was formed. After centrifuging, the extractant phase was analyzed using a spectrophotometric detection method. Some important parameters that might affect the extraction efficiency were optimized (HCl, 0.6molL(-1); dithizone, 4.0 × 10(-6)molL(-1); ionic liquid, 100μL). Under the optimum conditions, good linear relationship, sensitivity, and reproducibility were obtained. The limit of detection (LOD) (3Sb/m) was 1.5μgL(-1), and the relative standard deviation (RSD) was 1.2% for 30μgL(-1) of Se(IV). The linear range was obtained in the range of 5-60μgL(-1). It was satisfactory to analyze rice and various water samples.

Determination of Nickel Using Cold-Induced Aggregation Microextraction Based on Ionic Liquid Followed by Flame Atomic Absorption Spectrometry

Determination of Nickel Using Cold-Induced Aggregation Microextraction Based on Ionic Liquid Followed by Flame Atomic Absorption Spectrometry

Combination of cold-induced aggregation microextraction and central composite design for preconcentration and determination of copper in food and water samples

An efficient, simple, and rapid cold-induced aggregation microextraction method was applied to preconcentrate copper (II) ions from water and food samples as a prior step to its determination by flame atomic absorption spectrometry. In this method, small amounts of 1-hexyl-3-methylimidazolium hexafluorophosphate [Hmim][PF6] and 1-hexyl-3-methylimidazolium bis (trifluoromethylsulfonyl) imide [Hmim][Tf2N] as hydrophobic ionic liquids (ILs) and extractant solvents were dissolved in the sample solution containing Triton X-114. After dissolving, the solution was cooled in an ice bath and a cloudy solution was formed of IL fine droplets due to the decrease of IL solubility. The effective parameters, such as pH, amount of chelating agent and IL, temperature, and concentration of salt were optimized by a fractional factorial design to identify the most important parameters and their interactions, and central composite methodology was used to achieve the optimum point of effective parameters to the response. Under the optimum conditions, the calibration graph was linear in the range of 2–100 μg L-1 with a correlation coefficient of 0.996 and a limit of detection of 0.42 μg L-1. The relative standard deviation was 2.61% (n = 6). The obtained enrichment factor was 75 for copper. The interference effect of anions and cations was also tested. The proposed method was compared with the other methods and applied to the analysis of several real and spiked samples and the satisfactory relative recoveries (96.5–101.3%) were obtained.

Cold-Induced Aggregation Microextraction Technique based on Ionic Liquid for Preconcentration and Determination of Nickel in Food Samples

The determination of nickel in food samples and well water using cold induced aggregation microextraction combined UV-Vis spectrophotometry is described. The extraction of nickel was performed in the presence of dimethylglyoxime (DMG) as the complexing agent. In this method, sodium hexafluorophosphate (NaPF6) was added to the sample solution containing small amounts of 1-hexyl-3-methylimidazolium hexafluorophosphate [Hmim][PF6] as extraction solvent. Parameters governing the extraction efficiency such as amount of ionic liquid, pH, temperature and ionic strength were optimized. The applicability of the technique was evaluated by the determination of trace nickel in different types of vegetables. Under the optimum conditions, the calibration curve was linear in the concentration range 8-200 ng mL-1 with correlation coefficient (r2) of 0.9996. The limit of detection (LOD) of 0.47 ng mL-1 and enhancement factor of 186 were obtained for nickel. The relative standard deviation (RSD) was 3.7% for 40 ng L-1 nickel (n = 10).

The ultratrace detection of crystal violet in fish and environmental water samples using cold-induced aggregation microextraction based on ionic liquid (IL-CIAME)

A new method based on ionic liquid cold-induced aggregation microextraction (IL-CIAME) in combination with fiber optic-linear array detection spectrophotometry (FO-LADS) has been developed for the analysis of crystal violet (CV) in saline samples. In this methodology, a suitable temperature is used to fully dissolve very small amounts of 1-hexyl-3-methylimidazolium hexafluorophosphate [Hmim][PF6] and 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide [Hmim][Tf2N] as hydrophobic ionic liquids (ILs) and extractant solvents in the sample solution without the use of a disperser solvent. After dissolving, the solution was cooled in an ice bath and a cloudy solution of IL fine droplets was formed due to the decrease of IL solubility. After centrifuging, the fine droplets of the extractant phase settled to the bottom of the conical-bottom centrifuge tube. In this method, which is robust against high content of salt and water-miscible organic solvents, various parameters were investigated and optimized. Under the optimum conditions, the limit of detection (LOD) of the method was 1.16 μg L−1 and the relative standard deviation (RSD) for 20 μg L−1 CV was 2.30%. The obtained results indicated that the developed method is an excellent alternative for routine analysis in the environmental field.

Ultrasound assisted cold-induced aggregation: an improved method for trace determination of volatile phenol

We report on a simple, rapid and efficient extraction procedure, referred to as ultrasound-assisted cold-induced aggregation (USA-CIAME), for the extraction of phenol from aqueous samples. In this method, very small amounts of the ionic liquid 1-hexyl-3-methylimidazolium hexafluorophosphate (the extractant) are dissolved in a sample solution containing phenol and ultrasonicated for 1 min. The solution is cooled in an ice bath upon which a cloudy solution forms. Following centrifugation, the extractant phase settles at the bottom of a conical-bottom centrifuge tube. Phenol is photometrically determined after its chromogenic reaction with 4-aminoantipyrine in the presences of hexacyanoferrate at pH 10.0. Compared to the conventional cold-induced aggregation microextraction (CIAME) and dispersive liquid liquid microextraction (DLLME), the optimized approach displays the highest extraction efficiency at room temperature, and the shortest extraction time (5 min). Key parameters affecting the performance were evaluated and optimized. Under optimum conditions, the limit of detection of phenol is 0.86 μg L−1, and the enrichment factor is 75. The calibration graph as linear over the range from 3 to 150 μg L−1, and the relative standard deviation is 2.65% (n = 5). The method was successfully applied to the determination of phenol in water samples.

Separation and determination of trace level of gold from hydrochloric acid solutions using ultrasound-assisted cold-induced aggregation microextraction

A new methodology ultrasound assisted cold-induced aggregation microextraction (USA-CIAME) was developed for the determination and extraction of ultra trace levels of Au3+ from aqueous hydrochloric acid solutions by pure ionic liquid (IL), in the absence of chelating agents. The extraction behaviour of metal ions by [Hmim]PF6 was particularly studied. Moreover, the stripping of metal ions from the IL phase was investigated. Au3+ in IL phase can be quantitatively recovered by NaPF6. Recycle testing indicated that IL loss can be avoided by the additon of [Hmim]+ to the initial AuCl4− solutions before extraction and/or using PF6− solutions for stripping. The main factors affecting Au3+ extraction, the amount of IL, the pH of the sample solutions, and the chloride ion concentration on extraction efficiencies were carefully studied. A linear calibration was obtained for 1.5 to 200 μg L−1 of Au3+ and the limit of detection was 0.59 μg L−1. The validation of this method was done by recovery and determination of trace amount of gold in river, sea water and geological samples with satisfactory results.

Determination of silver in real samples using homogeneous liquid-liquid microextraction based on ionic liquid

A new solvent-free mode of homogeneous liquid-liquid microextraction based on ionic liquid (IL) named as modified cold induced aggregation microextraction (M-CIAME), was developed. The method is a fast, solvent free, robust against high medium salt content, and simple for extraction and preconcentration of metal ions from various samples. The extraction of silver was preformed in the presence of 4,4-bis(dimethylamino)thiobenzophenone (TMK) as the complexing agent and sodium hexafluorophosphate (NaPF6) was added to the sample solution (50°C) containing small amounts of 1-hexyl-3-methylimidazolium tetrafluoroborate [Hmim][BF4]. Afterwards, the solution was placed in the ice bath and a cloudy solution was formed due to the decrease of IL solubility. After centrifuging, the fine droplets of extraction phase were settled of the bottom of the conical bottom glass centrifuge tube. Under the optimum conditions, the limit of detection (LOD) was 0.4 ng/mL. The relative standard deviation (RSD) was 1.8% for 50 ng/mL of silver (n = 5).

Modified-cold induced aggregation microextraction based on ionic liquid and fibre optic-linear array detection spectrophotometric determination of palladium in saline solutions

In this research, a novel microextraction technique based on ionic liquids (ILs) termed in modified-cold induced aggregation microextraction (M-CIAME) was used for determination of palladium in saline solution. 1-(2-pyridylazo)-2-naphtol (PAN) was chosen as the complexing agent. Analysis was carried out using fibre optic-linear array detection spectrophotometric method which is suitable for analyte determination after microextraction. M-CIAME is based on phase separation phenomenon of ionic liquids in aqueous solutions. This method is simple and rapid for extraction and preconcentration of metal ions from water samples. It can be applied for the sample solutions containing much higher concentrations of salt, in comparison with CIAME (cold induced aggregation microextraction). Furthermore, this technique is much safer in comparison with other microextraction techniques in which organic solvent is used as the extraction solvent. Some effective parameters on extraction and complex formation such as amount of IL, salt effect, pH, concentration of the chelating agent and the other parameters were optimised. Under the optimum conditions, the limit of detection (LOD) and repeatability, expressed as relative standard deviation (n = 5) for 20 ng mL−1 of palladium were 0.4 ng mL−1 and 2.23%, respectively. The extraction percentage was 86%.

Recent Advances of Microextraction with Ionic Liquid as Friendly Acceptor Phase for Sample Preparation in Analytical Chemistry

Ionic liquid has been rapidly developed as an environment-friendly acceptor phase for microextraction and sample preparation in analytical chemistry in recent years. Present microextraction with ionic liquid mainly includes liquid phase microextraction, single drop liquid phase microextraction, solid phase microextraction, dispersive liquid phase microextraction and cold induced aggregation microextraction. In general, the microextraction with ionic liquid exhibits higher extraction efficiency and enrichment factor than that with organic solvent. Hydrophobic ionic liquids are difficult to fully mix with aqueous phase due to very high interfacial tension between the ionic liquid and water, a relatively long extraction time and manual stirring process were strongly required for improving extraction efficiency of the microextraction with ionic liquid. Recently, a novel microextraction technology termed as dispersive liquid phase microextraction was developed and applied rapidly, in which the ionic liquid was dispersed completely into the aqueous phase and the analytes will more easily migrate into the ionic liquid phase because of the much large contact area, its extraction time was shorten remarkably and whole extraction can be completed within several minutes. Moreover, the combinations of many modern analytical technologies with the ionic liquid microextraction were investigated and improved, special to gas chromatography and gas chromatography mass spectrometry. These have widely been applied to determination of ultra trace metal and organic compound in water or other samples. Up to now, the microextractions with ionic liquid have increasingly become one of most important method for samples preparation in analytical chemistry.

Ionic liquid-based modified cold-induced aggregation microextraction (M-CIAME) as a novel solvent extraction method for determination of gold in saline solutions

Modified-cold-induced aggregation microextraction (M-CIAME) was used for determination of gold in saline solutions. It is robust against the much higher concentration of salt (up to 40%). In this method sodium hexafluorophosphate (NaPF 6) was added to the sample solution containing Au-TMK complex and a very small amount of 1-hexyl-3-methylimidazolium tetrafluoroborate [Hmim][BF 4]. Afterward the solution was cooled in an ice bath and a cloudy solution was formed. After centrifuging, the extractant phase was analyzed using a spectrophotometric detection method. Under the optimum conditions, the limit of detection (LOD) was 0.7 ng mL −1 and the relative standard deviation (RSD) was 1.65% for 50 ng mL −1 gold. The method was applied for the determination of trace amount of Au in mineral and seawater with satisfactory results.

Microextraction technique based on ionic liquid for preconcentration and determination of palladium in food additive, sea water, tea and biological samples

Modified cold-induced aggregation microextraction (M-CIAME) is a fast and simple method for extraction and preconcentration of metal ions from samples with high salt content. Furthermore, this technique is much safer in comparison with the organic solvent extraction. The extraction of palladium (Pd) was performed in the presence of Michler thioketone (TMK) as the complexing agent. In this method, sodium hexafluorophosphate (NaPF6) was added to the sample solution containing small amounts of 1-hexyl-3-methylimidazolium tetrafluoroborate [Hmim][BF4]. Afterwards, the solution was placed in the ice bath and a cloudy solution was formed. After centrifuging, the extraction phase was settled. Under the optimum conditions, the limit of detection (LOD) was 0.2ngmL−1. The relative standard deviation (RSD) was 1.7% for 40ngmL−1 of palladium (n=5).

Cold-induced aggregation microextraction based on ionic liquids and fiber optic-linear array detection spectrophotometry of cobalt in water samples

A new simple and rapid cold-induced aggregation microextraction (CIAME) method was applied to preconcentrate cobalt(II) ions from water samples as a prior step to its determination by fiber optic-linear array detection spectrophotometry (FO-LADS). In this method, very small amounts of 1-hexyl-3-methylimidazolium hexafluorophosphate [Hmim][PF 6] and 1-hexyl-3-methylimidazolium bis (trifluoromethylsulfonyl) imide [Hmim][Tf 2N] as hydrophobic ionic liquids (ILs) and extractant solvents were dissolved in the sample solution containing Triton X-114 (anti-sticking agent). 1-(2-Pyridylazo)-2-naphthol (PAN) was chosen as the complexing agent. After dissolving, the solution was cooled in the ice bath and a cloudy solution was formed of IL fine droplets due to the decrease of IL solubility. After centrifuging, the fine droplets of extractant phase were settled to the bottom of the conical-bottom centrifuge tube. Analysis was carried out by a fiber optic-linear array detector spectrophotometer at 570 nm. In this method, which is robust against high content of salt and water-miscible organic solvents, various parameters were investigated and optimized. The applicability of the technique was evaluated by the determination of trace amounts of cobalt in several water samples. Under the optimum conditions, the limit of detection (LOD) of the method was 0.14 ng mL −1 and the relative standard deviation (R.S.D.) for 30 ng mL −1 cobalt was 2.32%.

Cold-induced aggregation microextraction: A novel sample preparation technique based on ionic liquids

In this research, a novel microextraction technique based on ionic liquids (ILs) termed cold-induced aggregation microextraction (CIAME) is developed. In this method, very small amounts of 1-hexyl-3-methylimidazolium hexafluorophosphate [Hmim][PF 6] and 1-hexyl-3-methylimidazolium bis (trifluoromethylsulfonyl) imide [Hmim][Tf 2N] (as extractant solvents) were dissolved in a sample solution containing Triton X-114 (as an anti-sticking agent). Afterwards, the solution was cooled in the ice bath and a cloudy solution was formed. After centrifuging, the fine droplets of extractant phase were settled to the bottom of the conical-bottom glass centrifuge tube. CIAME is a simple and rapid method for extraction and preconcentration of metal ions from water samples and can be applied for the sample solutions containing high concentration of salt and water miscible organic solvents. Furthermore, this technique is much safer in comparison with the organic solvent extraction. Performance of the technique was evaluated by determination of the trace amounts of mercury as a test analyte in several real water samples. Michler thioketone (TMK) was chosen as a complexing agent. Analysis was carried out using spectrophotometric detection method. Type and amount of IL and the surfactant, temperature and the other parameters were optimized. Under the optimum conditions, the limit of detection (LOD) of the method was 0.3 ng mL −1 and the relative standard deviation (R.S.D.) was 1.32% for 30 ng mL −1 mercury.