The critical evaluation of the effects of imidazolium-based ionic liquids on the separation efficiency of selected biogenic amines and their metabolites during MEKC analysis

This study uses micellar electrokinetic chromatography (MEKC) to evaluate how ILs in the background electrolyte (BGE) affect the separation efficiency of biogenic amines (BAs). Specifically, this research focuses on 12 ILs built from cations containing an imidazole ring with different alkyl substituents and anions, as well as one IL containing a pyridinium cation with tetrafluoroborate anion. All analyzed ILs, which were added to the BGE in concentrations ranging from 1 to 20 mM, were tested for their ability to improve the electrophoretic separation of selected BAs, namely: homovanillic acid (HVA), vanililmandelic acid (VMA), dihydroxyphenylglicol (DHPG), 3-metoxy-4-hydroxyphenyl glicol (MHPG), normetanephrine (NM), metanephrine (M), and dihydroxyphenylacetic acid (DOPAC). The results showed that the most effective ILs added to the BGE were those with a chloride anion (1-hexyl-3-methylimidazolium chloride [HMIM+Cl-] and 1-ethyl-3-methylimidazolium chloride [EMIM+Cl-]) and those with a tetrafluoroborate anion (1-hexyl-3-methylimidazolium tetrafluoroborate [HMIM + BF4-]). Improved separation efficiency was also obtained for the BGE containing 1-hexyl-3-methylimidazolium hexafluorophosphate [HMIM + PF6-]. On the other hand, ILs with trifluoromethanesulfonate [OTf-] or bis(trifluoromethylsulfonyl)imide [NTf2-] anions, even at low concentrations in the BGE, disturbed the flow of current through the capillary and worsened the separation process. Overall, this study provides a crit...

Source: Talanta - December 3, 2021 Category: Chemistry Authors: Natalia Kaczmarczyk Julita Ci żewska Natalia Treder Natalia Mi ękus Alina Plenis Piotr Kowalski Anna Roszkowska Tomasz B ączek Ilona Ol ędzka Source Type: research