Capillary isotachophoresis for the analysis of ionic liquid entities

Abstract

Simple, selective and sensitive isotachophoretic methods for the analysis of ionic liquid (IL) compartments were developed in this study. A leading electrolyte containing 10 mM L-histidine + 10 mM histidine hydrochloride and a terminating electrolyte containing 5 mM glutamic acid + 5 mM L-histidine were selected to separate nitrate(V), chlorate(V), hexafluorophosphate, dicyanimide, trifluoromethanesulfonate, phosphate(V) and bis(trifluoromethanesulfonyl)imide in anionic mode. In contrast, seven short-chain alkylimidazolium, alkylpyrrolidinium, alkylpyridinium and non-chromophoric tetraalkylammonium and tetraalkylphosphonium IL cations were separated with 10 mM potassium hydroxide + 10 mM acetic acid as leading electrolyte, and 10 mM beta-alanine + 10 mM acetate as terminating electrolyte. Both methods were optimized and validated with good analytical performance parameters. LOD was about 3-5 microM, and the repeatability lay in the range of 1.06-5.59%. These methods were evaluated for their applicability to the analysis of soil samples and freshwater contaminated with ILs. In light of hitherto the absence of reports on the determination of non-chromophoric IL cations, this study delivers for the first time a universal method enabling analysis of these species. Moreover, as there is still significant lack of methodologies of IL anion analysis, the obtained results offer an interesting alternative in that matter.

Chromatographic Techniques in the Research Area of Lithium Ion Batteries: Current State-of-the-Art

“…The synthesis of 1-butyl-3-methylimidazolium chloride was monitored in terms of process control after method development. Additionally, impurities in commercially available Two capillary isotachophoresis-based methods for the analysis of ILs were developed by Markowska et al [144]. They investigated both anions and cations with the respected methods: nitrate(V), chlorate(V), hexafluorophosphate, dicyanimide, trifluoromethanesulfonate, phosphate(V) and bis(trifluoromethanesulfonyl)imide anions and seven short-chain alkylimidazolium, alkylpyrrolidinium, alkylpyridinium and non-chromophoric tetraalkylammonium and tetraalkylphosphonium IL cations.…”

Recent advances in enrichment techniques for trace analysis in capillary electrophoresis

“…The stacking is achieved by introducing a plug of LE followed by a section of sample solution with TE, or reversely, by introducing a plug of sample solution with LE followed by a section of TE . The tITP method has been successfully applied to the on‐line enrichment of nonsteroidal anti‐inflammatory drugs , ionic liquid entities , doping substances , and peptides .…”

Recent progress in analytical capillary isotachophoresis

“…By using different electrolyte systems in the preseparation and analytical capillary, LODs from 0.85 to 3.1 mg/L and LOQs from 2.8 to 10 mg/L were obtained using conductivity and UV detection (LE1: 10 mM HCl, β‐alanine, 0.1% HEC, pH 3.9; LE2: 10 mM HCl, aminocaproic acid, 0.1% HEC, pH 5.00; TE: 5 mM caproic acid). Markowska and Stepnowski described ITP systems for the analysis of various low molecular mass anions and cations in soil samples and freshwater. LODs were on the 3–5 μM level (anions: LE: 20 mM histidine, 10 mM HCl, pH 5.5; TE: 5 mM glutamic acid, 5 mM histidine, pH 4.65; cations: LE: 10 mM KOH, 10 mM HAc, pH 5.34; TE: 10 mM β‐alanine, 10 mM HAc, pH 3.45; conductivity detection).…”

“…By using different electrolyte systems in the preseparation and analytical capillary, LODs from 0.85 to 3.1 mg/L and LOQs from 2.8 to 10 mg/L were obtained using conductivity and UV detection (LE1: 10 mM HCl, ␤-alanine, 0.1% HEC, pH 3.9; LE2: 10 mM HCl, aminocaproic acid, 0.1% HEC, pH 5.00; TE: 5 mM caproic acid). Markowska and Stepnowski [53] (6), tetrabutylphosphonium (7). For used electrolytes, see text.…”