Hydrophilic interaction liquid chromatography for separation and quantification of selected room-temperature ionic liquids
ABSTRACT Hydrophilic interaction liquid chromatography (HILIC) is an alternative technique to ion pairing-reversed-phase liquid chromatography (IP-RPLC) and classical RPLC for separation of alkylimidazolium room-temperature ionic liquids (RTILs). Particularly, HILIC offers better retention and selectivity for short-chains RTILs imidazolium compounds. HILIC mechanisms were investigated by studying the influence of organic modifier content and salt concentration in the mobile phase. HILIC method was validated by quantifying 1-butyl-3-methylimidazolium cation (BMIM) degradation under gamma radiation at 2.5MGy. Development of separative reproducible analytical methods, including for low concentration, applicable to RTILs are today mandatory to improve RTILs chemistry.
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ABSTRACT: In the last decade, ionic liquids have shown great promise in a plethora of applications. However, little attention has been paid to the characterisation of the purity of these fluids, which has ultimately led to non-reproducible data in the literature. In order to facilitate specification of ionic liquids, a number of analytical protocols with their limits of detection (where available) have been compiled, including methods of other authors. In particular, quantitative methods have been developed and summarised for the determination of the total ionic liquid content, residual unreacted ionic liquid starting material and by-products (amines, alkylating agents, inorganic halides), solvents from extraction procedures and water, in addition to decomposition products and total volatiles.Green Chemistry 01/2008; 10(11). DOI:10.1039/b808532c · 6.85 Impact Factor
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ABSTRACT: The growing interest in ionic liquids (ILs) has resulted in an exponentially increasing production of analytical applications. The potential of ILs in chemistry is related to their unique properties as non-molecular solvents: a negligible vapor pressure associated to a high thermal stability. ILs found uses in different sub-disciplines of analytical chemistry. After drawing a rapid picture of the physicochemical properties of selected ILs, this review focuses on their use in separation techniques: gas chromatography (GC), liquid chromatography (LC) and electrophoretic methods (CE). In LC and CE, ILs are not used as pure solvents, but rather diluted in aqueous solutions. In this situation ILs are just salts. They are dual in nature. Too often the properties of the cations are taken as the properties of the IL itself. The lyotropic theory is recalled and the effects of a chaotropic anion are pointed out. Many results can be explained considering all ions present in the solution. Ion-pairing and ion-exchange mechanisms are always present, associated with hydrophobic interactions, when dealing with IL in diluted solutions. Chromatographic and electrophoretic methods are also mainly employed for the control and monitoring of ILs. These methods are also considered. ILs will soon be produced on an industrial scale and it will be necessary to develop reliable analytical procedures for their analysis and control.Journal of Chromatography A 04/2008; 1184(1-2):6-18. DOI:10.1016/j.chroma.2007.11.109 · 4.26 Impact Factor
Article: Method development for HILIC assays[Show abstract] [Hide abstract]
ABSTRACT: In this review, method development for hydrophilic interaction LC (HILIC) is highlighted. HILIC is a chromatographic technique that uses aqueous-organic solvent mobile phases with a high organic-solvent fraction, and a hydrophilic stationary phase. It is mainly applied for the separation of polar and hydrophilic compounds. Method development, in general, can be done uni- or multivariately. In the univariate approach, the factors that are expected to potentially affect the separation of the compounds will be examined sequentially and one-at-a-time. All HILIC methods found in the literature were developed in this way. For these methods, the analytes, the considered factors, the selected responses, and the finally chosen experimental conditions are discussed in this review. Where examined, the method validation and the comparison with other analytical assay methods is also described. For the multivariate method-development approach, which is based on the use of experimental designs, only a possible strategy is presented, because of the lack of relevant publications in the literature.Journal of Separation Science 05/2008; 31(9):1438-48. DOI:10.1002/jssc.200700680 · 2.59 Impact Factor