Gaining insight in the behaviour of imidazolium-based ionic liquids as additives in reversed-phase liquid chromatography for the analysis of basic compounds

Ubeda-Torres, M. T.; Ortiz-Bolsico, C.; Garcı́a-Alvarez-Coque, M.C.; Ruiz-Ángel, M.J.

doi:10.1016/j.chroma.2014.12.064

Cited by 52 publications

(36 citation statements)

References 37 publications

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“…Based on previous experience [23,24], a fixed concentration of 15% acetonitrile was selected for the mobile phases. An ionic liquid (Table 1) or TEA was then added at concentrations 10, 20, 30 and 40 mM.…”

Section: Experimental Designsmentioning

confidence: 99%

“…Successive additions of the ILs decreased the [29]. In previous work [23,24], it was checked that the cation can establish electrostatic and hydrophobic interactions with the anionic silanols and the alkyl bonded phase, respectively, whereas the anion interacts hydrophobically with the stationary phase. This gives rise to an asymmetric bilayer, positively or negatively charged depending on the relative adsorption of the IL.…”

Section: Solute-stationary Phase and Solute-mobile Phase Interactionsmentioning

confidence: 99%

“…Since both the cation and the anion are capable of interacting with the stationary phase, they have a dual character [17]. In previous work, it was observed that the adsorption effect on the alkyl-bonded stationary phase was larger for bulky imidazolium ILs [23,24]. The extension of the interactions of the IL cation and anion with the stationary phase and ion-pairing, ion-exchange, and hydrophobic partitioning present in the chromatographic process complicates the interpretation of the mechanism of retention.…”

Section: Introductionmentioning

confidence: 99%

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Estimation of Solute-Stationary Phase and Solute-Mobile Phase Interactions in the Presence of Ionic Liquids

Ruiz-Ángel

2019

Separations

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The presence of free silanols on alkyl-bonded reversed-phase stationary phases is responsible for broad and asymmetrical peaks when basic drugs are chromatographed with conventional octadecylsilane (C18) columns due to ionic interactions. In the last few years, ionic liquids (ILs) have attracted attention to reduce this undesirable silanol activity. ILs should be considered as dual modifiers (with a cationic and anionic character), which means that both cations and anions are able to adsorb on the stationary phase, creating a positively or negatively charged layer, depending on the relative adsorption. The accessibility of basic compounds to the silanols is prevented by both the IL cation and anion, improving the peak profiles. A comparative study of the performance of six imidazolium-based ILs, differing in their cation/anions, as modifiers of the chromatographic behavior of a group of ten β-adrenoceptor antagonists, is addressed. Mobile phases containing cationic amines (triethylamine and dimethyloctylamine) were used as a reference for the interpretation of the results. Using a mathematical model based on two chemical equilibria, the association constants between the solutes and modified stationary phase as well as those between solutes and the additive in the mobile phase were estimated. These values, together with the changes in retention and peak shape, were used to obtain conclusions about the retention mechanism, changes in the nature of the chromatographic system, and silanol suppression effect.

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Section: Experimental Designsmentioning

confidence: 99%

Section: Solute-stationary Phase and Solute-mobile Phase Interactionsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Estimation of Solute-Stationary Phase and Solute-Mobile Phase Interactions in the Presence of Ionic Liquids

Ruiz-Ángel

2019

Separations

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“…In recent years, the applications of ILs in the fields of GC stationary phases [12], LC stationary phases [13][14][15][16][17][18] and mobile phase additives [19,20] have received increasing attention. There are some reports on the analysis of organic substances such as alkaloids [21][22][23][24][25] and metal ions [26][27][28] by using ionic liquids as mobile phase additives, but there are few reports on the analysis of anions [29,30] which needs to be further studied extensively.…”

Section: Introductionmentioning

confidence: 99%

Ionic liquids as mobile phase additives for determination of thiocyanate and iodide by liquid chromatography

Cui

2019

J of Separation Science

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An analytical method was developed for the simultaneous determination of thiocyanate and iodide by reversed‐phase liquid chromatography with UV detection using imidazolium ionic liquids as mobile phase additives. The chromatographic behaviors of the two anions on a C18 column were studied and compared with four types of reagents including imidazolium ionic liquids, pyridinium ionic liquids, 4‐aminophenol hydrochloride and tetrabutylammonium as mobile phase additives. The effects of the concentrations of imidazolium ionic liquids, organic solvents and detection wavelength on separation and detection of the anions were investigated. The role of ionic liquids, retention rules and mechanisms were discussed. The separation of the anions was performed on the C18 reserved‐phase column using acetonitrile‐0.3 mmol/L 1‐amyl‐3‐methylimidazolium tetrafluoroborate (10:90, v/v) as mobile phase, with column temperature of 35°C, flow rate of 1 mL/min and detection wavelength of 210 nm. Under these conditions, the two anions can be completely separated within 6 min. The limits of detection were 0.05 mg/L. The method was applied for the determination of thiocyanate and iodide in ionic liquid samples and iodide drugs, and the spiked recoveries ranged from 97 to 101%. The method is simple, accurate and meets the requirements of quantitative analysis for thiocyanate and iodide.

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“…Recently, a review has been published, which comments the use and interaction mechanism of ILs as additives of mobile phase in HPLC . ILs have been used as mobile phase additives in HPLC to separate alkaloids , anilines , amines , amino acids , antibiotics , antidepressants , β‐blockers , heterocyclic aromatic amines , mixtures of diverse drugs , proteins , and phenols , but its application in the analysis of FWAs has not been reported. The most common ILs used for additives are imidazolium, pyridinium, and quaternary ammonium cations, associated with anions like BF 4 − , PF 6 − , Cl – or Br − .…”

Section: Introductionmentioning

confidence: 99%

Ionic liquid as a mobile phase additive in high‐performance liquid chromatography for the simultaneous determination of eleven fluorescent whitening agents in paper materials

Wang

Chen

Qiu

et al. 2016

J of Separation Science

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In the present study, 11 4,4'-diaminostilbene-2,2'-disulfonic acid based fluorescent whitening agents with different numbers of sulfonic acid groups were separated by using an ionic liquid as a mobile phase additive in high-performance liquid chromatography with fluorescence detection. The effects of ionic liquid concentration, pH of mobile phase B, and composition of mobile phase A on the separation of fluorescent whitening agents were systematically investigated. The ionic liquid tetrabutylammonium tetrafluoroborate is superior to tetrabutylammomnium bromide for the separation of the fluorescent whitening agents. The optimal separation conditions were an ionic liquid concentration at 8 mM and the pH of mobile phase B at 8.5 with methanol as mobile phase A. The established method exhibited low limits of detection (0.04-0.07 ng/mL) and wide linearity ranges (0.30-20 ng/mL) with high linear correlation coefficients from 0.9994 to 0.9998. The optimized procedure was applied to analyze target analytes in paper samples with satisfactory results. Eleven target analytes were quantified, and the recoveries of spiked paper samples were in the range of 85-105% with the relative standard deviations from 2.1 to 5.1%. The obtained results indicated that the method was efficient for detection of 11 fluorescent whitening agents.

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Gaining insight in the behaviour of imidazolium-based ionic liquids as additives in reversed-phase liquid chromatography for the analysis of basic compounds

Cited by 52 publications

References 37 publications

Estimation of Solute-Stationary Phase and Solute-Mobile Phase Interactions in the Presence of Ionic Liquids

Estimation of Solute-Stationary Phase and Solute-Mobile Phase Interactions in the Presence of Ionic Liquids

Ionic liquids as mobile phase additives for determination of thiocyanate and iodide by liquid chromatography

Ionic liquid as a mobile phase additive in high‐performance liquid chromatography for the simultaneous determination of eleven fluorescent whitening agents in paper materials

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