Capillary Electrophoretic Application of 1-Alkyl-3-methylimidazolium-Based Ionic Liquids

Abstract

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.

Analysis of phthalates via HPLC-UV in environmental water samples after concentration by solid-phase extraction using ionic liquid mixed hemimicelles

“…RTILs belong to a relatively new class of solvents which are amphiphilic molecules with a hydrophilic polar headgroup (ionic in nature) and a hydrophobic hydrocarbon chain (the tail). In recent years, RTILs have attracted great attentions due to their unique chemical and physical properties such as nonvolatile (environmentally benign), excellent solvation qualities, non-flammable and high thermal stability [22,23]. As a result, RTILs are widely used in liquid-liquid extraction [24,25], synthesis [26,27], separation [28,29] and electrochemistry [30,31].…”

Ionic liquids as mobile phase additives for high‐performance liquid chromatography separation of phenoxy acid herbicides and phenols

“…It was noteworthy that the maximum absorbance wavelength for [C 4 MIM]Cl, [C 8 MIM]Cl and C 10 MIM]Cl ionic liquid is 210 nm, and these ionic liquids have no UV absorbance at 280 nm. Accordingly, the selected ionic liquids did not increase the general UV absorbance background in the mobile phase.…”

“…3). Comparing the retention of PNP with that of MCPP and 2,4-D, it was obvious to find that PNP was less retained than MCPP and 2,4-D in the [C 4 MIM]Cl mobile phase, whereas it became more retained than the latter two compounds when in the [C 8 MIM]Cl or [C 10 MIM]Cl mobile phase. Accordingly, the normal elution sequence was broken by PNP (Fig.…”

“…With many novel properties, such as low volatility, no flammability and good thermal stability, these ionic liquids are promising ''green'' solvents for replacing the traditional toxic solvents in many fields [1,2]. Presently, ionic liquids attract great interests in separation sciences and analytical chemistry [3][4][5]; and using ionic liquids as mobile phase additives for the separation of polar compounds by reversed-phase high performance liquid chromatography (RP-HPLC) was highlighted. Current studies mostly focused on basic compounds, such as ephedrines [6], catecholamines [7], adrenergic amines [8], amines [9], basic drugs [10], vitamins [11] and so on; only a few reseach dealt with acid compoulds [12][13][14].…”

“…Because these pollutants are weak acids with pKa values in the range of 2-11, the pH of the mobile phase should be adjusted to one unite lower than the pKa value (pHrpKa-1) to make these analytes uncharged and thus retain on the common RP-HPLC column [21,23]. However, such low pH usually exceeded the normal working pH range of RP-HPLC column (pH [3][4][5][6][7][8]. So an alternative method using ion-pair reagents as mobile phase additives was developed for separating the acid analytes in the neutral mobiles phase, in which the acid analytes were usually as their negatively charged ion form [25].…”