Separation of ternary systems of hydrophilic ionic liquid with miscible organic compounds by RPLC with refractive index detection

Abstract

A rapid and simple analytical method was developed for the simultaneous and quantitative determination and separation of hydrophilic imidazolium ionic liquids (ILs) (1-butyl-3-methylimidazolium chloride, [C(4)mim]Cl; 1-hexyl-3-methylimidazolium chloride, [C(6)mim]Cl; 1-octyl-3-methylimidazolium chloride, [C(8)mim]Cl; 1-allyl-3-methylimidazolium chloride, [Amim]Cl; or 1-allyl-3-methylimidazolium bromide, [Amim]Br) with miscible ethyl acetate and EtOH and their mixtures using reverse phase liquid chromatography coupled with refractive index detection (RPLC-RI). The influence of 60 to 100% (volume percentage) methanol in the mobile phase on the IL systems ([C(4)mim]Cl, [C(6)mim]Cl, [C(8)mim]Cl, [Amim]Br, or [Amim]Cl)-ethyl acetate-EtOH was investigated. The optimum mobile phase for the system [C(8)mim]Cl-ethyl acetate-EtOH, [C(4)mim]Cl-ethyl acetate-EtOH, [Amim]Br-ethyl acetate-EtOH and [Amim]Cl-ethyl acetate-EtOH was methanol/water (60:40, v/v), and methanol/water (70:30, v/v) for [C(6)mim]Cl-ethyl acetate-EtOH. Under optimum mobile phase conditions for each system, the RSD of the retention time ranged from 0.02 to 0.04%, and the RSDs of the peak area percent ranged from 0.23 to 1.85%, which showed good reproducibility of the RPLC-RI method. The RPLC-RI method can determine IL, ethyl acetate, and EtOH simultaneously in 5 min, and the analytes, especially IL, can be eluted completely. The results show that the RPLC-RI method can be used to separate and determine ILs in mixtures with organic compounds simultaneously and quantitatively.

Determination of Pyridinium Ionic Liquid Cations by Reversed Phase Ion-Pair Chromatography Using Gradient Elution

“…The effects of distinct columns [18] as well as inorganic salts [19] on the separation of imidazolium cations were investigated. So far, one optimized procedure for separating ILs from the organic mixture by RPLC has been described [20]. Imidazolium ionic liquid cations have been determined by CE using citric buffer as running electrolyte [21], which was adaptive for the cations with different molecular masses.…”

Determination of Ferulic Acid in Angelica Sinensis after Solid-Liquid Separation using Ionic Liquid as the Solid Extractant

“…Ionic liquids (ILs) are generally considered as green solvents due to their high thermal stability, very low flammability and negligible vapor pressure. In particular, their highly tunable nature, this positions ILs as the only true designer solvents [7][8][9]. These characteristics make them to behave very outstanding properties when they are used as solvents compared to conventional molecular liquids.…”

Removal of Cr(III, VI) by quaternary ammonium and quaternary phosphonium ionic liquids functionalized silica materials

“…Ionic liquids (ILs) are generally considered as environmental benign solvents mainly due to their high thermal stability, very low flammability and negligible vapor pressure [17][18][19][20]. As a new type of solvent, template and a diffusion medium for extractant, ILs could be doped into the silica gel matrix and retain their chemical activity [21].…”