ARTICLE IN PRESS Isotachophoretic separation of selected imidazolium ionic liquids 3 (original) (raw)
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Isotachophoretic separation of selected imidazolium ionic liquids
Talanta, 2008
Results of determination of selected imidazolium ionic liquids by isotachophoresis (ITP) with conductometric detection was presented. The effects of the molar mass of different ionic liquids on electrophoretic mobility was observed. The presented method was validated and basic validation parameters were determined. Limit of detection (LOD) in a 10 and 25 ng/L for anions and cations, respectively, is very satisfied. Thanks to its low cost and high rate, the presented method can be used in qualitative routine analysis as an alternative technique to liquid chromatography.
Capillary electrophoretic separation of cationic constituents of imidazolium ionic liquids
ELECTROPHORESIS, 2004
A capillary electrophoretic method for resolving selected imidazolium ionic liquid cations is reported. The method, in which citric buffer is used as the running electrolyte, is simple and reproducible. The separation of a standard mixture is in linear accordance with the relative molecular mass (M r ) of solutes regardless of the type of substitution (alkyl or aryl). The theoretical prediction of compounds as yet not analyzed is therefore possible; however, cations with identical molecular masses are inseparable with this method. Nevertheless, the method's quantitative analytical performance was excellent. The paper also discusses the applicability of a method for tracking the photodegradation kinetics of an exemplary ionic liquid.
International Journal of Molecular Sciences, 2006
Interest in ionic liquids for their potential in different chemical processes is constantly increasing, as they are claimed to be environmentally benign -excellent, nonvolatile solvents for a wide range of applications. The wide applicability of these compounds also demands reliable, relatively simple and reproducible analytical techniques. These methods must be applicable not only to different technical or natural matrices but also to the very low concentrations that are likely to be present in biological and environmental systems. In this review, therefore, methods for separating and analysing imidazolium-and pyridinium-type ionic liquids in aqueous matrices using high performance liquid chromatography (HPLC) and capillary electrophoresis (CE) are examined. The techniques for identifying ionic liquids are meant primarily to track the concentrations of ionic liquids as residues not only in products and wastes but also in biological or environmental samples. The application of hyphenated techniques in this field is intended to selectively separate the quaternary entity from other cationic and non-ionic species present in the matrix, and to enable its fine-scale quantification. Nowadays, methods developed for cation analysis are based mostly on reversed-phase high-performance liquid chromatography, ion chromatography, ion-pair chromatography and capillary electrophoresis, where various buffered mobile phases are used.
Analytical and Bioanalytical Chemistry, 2005
Owing to their favorable properties, ionic liquids have recently gained recognition as possibly environmentally benign solvents. Now among the most promising industrial chemicals, they have already been labeled ''green'', but this appellation seems due entirely to their very low vapor pressure. This growing interest in the various applications of ionic liquids will soon result in their presence in the environment. Therefore, reliable analytical tools for the environmental analysis of ionic liquids need to be developed urgently. This paper presents a newly developed analytical procedure for the enrichment of 1-alkyl-and 1-aryl-3-methylimidazolium ionic liquids from water samples. The method is based on cation exchange solid-phase extraction followed by selective elution. Pre-concentrated samples are subjected to high-performance liquid chromatography (HPLC) with an advanced methodology for qualitative and quantitative analysis. The overall procedure was verified by using standard spiked samples of tap water, seawater, and freshwater.
Advanced Synthesis & Catalysis, 2006
The reaction of N-alkylimidazole with alkyl sulfonates at room temperature affords 1,3-dialkylimidazolium alkanesulfonates as crystalline solids in high yields. The alkanesulfonate anions can be easily substituted by a series of other anions [BF 4 , PF 6 , PF 3 (CF 2 CF 3 ) 3 , CF 3 SO 3 and N(CF 3 SO 2 ) 2 ] by simple reaction of anions, salts, or acids in water at room temperature. Extraction with dichloromethane, filtration through a short basic alumina column and solvent evaporation affords the desired ionic liquids in 80 -95% yield. The purity ( > 99.4%) of these ionic liquids can be determined by 1 H NMR spectra using the intensity of the 13 C satellites of the imidazolium N-methyl group as internal standard.
2008
The reversed-phase high-performance liquid chromatographic (RP-HPLC) method has been developed and validated for the simultaneous determination of imatinib mesylate and of the impurity product in Glivec ® capsules (Novartis, Switzerland). Separations were performed on a X Terra TM 150 mm × 4.6 mm, 5 m particle size column at 25 • C. The mobile phase was a mixture of methanol-water-triethylamine (25:74:1, v/v/v) with flow rate of 1.0 ml min −1 . pH value of water-triethylamine (TEA) was adjusted to 2.4 with orthophosphoric acid before adding of methanol. UV detection was performed at 267 nm. Acetaminophen was used as an internal standard. The method was validated statistically for its selectivity, linearity, precision, accuracy and robustness. Due to its speed and accuracy, the method may be used for quality control analyses. (M. Medenica). tinib mesylate and STI 509-00 are shown in the following sheme.
Reversed phase liquid chromatography of alkyl-imidazolium ionic liquids
Journal of Chromatography A, 2006
Eleven 1-alkyl-3-methyl imidazolium ionic liquid (IL) salts were analyzed in reversed phase mode with a Kromasil C 18 column. The mobile phases were water-rich acetonitrile solutions (water content ≥70%, v/v) without any added salts. It is shown that it is possible to separate different ILs sharing the same cation and differing by the anion when salt-free mobile phases are used. When a buffer, acetate or phosphate salt, or any salt, such as sodium chloride or sodium tetrafluorobarate, is added to the mobile phase, the ILs differing only by their anions cannot be separated. ILs with different alkyl chains in the imidazolium cation are separated by mobile phases with or without added salts following a hydrophobic interaction behavior: log k is proportional to n C , the carbon number of the alkyl chain. Important differences in ion/stationary phase interactions are observed depending on the ionic content of the mobile phase. With salt-free mobile phases, the IL/C 18 stationary phase interactions correspond to concave isotherms associated with fronting peaks for all ILs. With mobile phase containing 0.01 M of salt, tailing IL peaks correspond to convex adsorption isotherms. Also, the IL retention factor depends on the concentration and nature of the added salt. Hexafluorophosphate chaotropic anions can adsorb on the Kromasil C 18 surface dramatically increasing the imidazolium cation retention factors.
Capillary Electrophoretic Application of 1Alkyl3-methylimidazolium-Based Ionic Liquids
Analytical Chemistry, 2001
Ionic substances with melting points at or close to room temperature are referred to as ionic liquids. Interest in ionic liquids for their potential in different chemical processes is increasing, because they are environmentally benign and are good solvents for a wide range of both organic and inorganic materials. In this study, a capillary electrophoretic method for resolving phenolic compounds found in grape seed extracts is reported. The method, in which 1-alkyl-3-methylimidazolium-based ionic liquids are used as the running electrolytes, is simple and reproducible. The separation mechanism seems to involve association between the imidazolium cations and the polyphenols. The role of the alkyl substituents on the imidazolium cations was investigated and will be discussed.
New Journal of Chemistry, 2009
A set of six imidazolium ionic liquids (1a-b, 2a-c, 3), that were solids at room temperature, were characterized by electrical impedance spectroscopy to obtain information about their polarization resistance (R p ), conductivity (s) and charge transfer activation energy (E a ). These experiments were performed at different temperatures in a glass micro-cell, equipped with three platinum electrodes. The observed conductivities were due to charge transfer processes of molecular oxygen at the electrode surface and mass transfer processes within the IL matrix. Higher temperatures resulted for all ionic liquids in increased conductivities. X-Ray diffraction of the ionic liquids 2a-c suggested that a higher degree of supramolecular two-dimensional organization, higher density, is related to an easier oxygen-electrode approximation, lower E a . Two distinct temperatures ranges were observed. The larger conductivity increases in the higher temperature range were explained by melting and fluxional behavior/reorientation phenomena of the ionic liquids and are due to enhanced oxygen diffusion (IL 3). In general, the understanding of imidazolium ionic liquid electrochemical properties could facilitate the development of new applications. a Activation energy calculated from the Arrhenius formula. b Temperature at the intersection of the low-and high-temperature range of the temperature dependent conductivity. c Melting point determined by differential scanning calorimetry on heating. d Ref. 42.
Reversed-phase liquid chromatography analysis of alkyl-imidazolium ionic liquids
Journal of Chromatography A, 2008
The reversed-phase high-performance liquid chromatographic (RP-HPLC) method has been developed and validated for the simultaneous determination of imatinib mesylate and of the impurity product in Glivec ® capsules (Novartis, Switzerland). Separations were performed on a X Terra TM 150 mm × 4.6 mm, 5 m particle size column at 25 • C. The mobile phase was a mixture of methanol-water-triethylamine (25:74:1, v/v/v) with flow rate of 1.0 ml min −1 . pH value of water-triethylamine (TEA) was adjusted to 2.4 with orthophosphoric acid before adding of methanol. UV detection was performed at 267 nm. Acetaminophen was used as an internal standard. The method was validated statistically for its selectivity, linearity, precision, accuracy and robustness. Due to its speed and accuracy, the method may be used for quality control analyses. (M. Medenica). tinib mesylate and STI 509-00 are shown in the following sheme.