Suppression of deleterious effects of free silanols in liquid chromatography by imidazolium tetrafluoroborate ionic liquids

Kaliszan, Roman; Marszałł, Michał Piotr; Markuszewski, Michał J.; Bączek, Tomasz; Pernak, Juliusz

doi:10.1016/j.chroma.2003.09.020

Cited by 154 publications

(70 citation statements)

References 24 publications

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“…Deleterious effects of free silanols are not fully removed by standard prevention procedures consisting of adding alkylamines or other amino quenchers to the eluents. Researchers found in (88) that ILs of the imidazolium tetrafluoroborate class, added to mobile phases at concentrations of 0.5-1.5% (v/v), blocked silanols and provided excellent thin-layer chromatographic separations of strongly basic drugs which were otherwise not eluted, even with neat acetonitrile as the mobile phase. The silanol-suppressing potency of imidazolium tetrafluoroborates was demonstrated to markedly exceed that of the standard mobile phase additives, such as triethylamine, dimethyloctylamine, and ammonia.…”

Section: Liquid Chromatographymentioning

confidence: 99%

Ionic Liquids in Chemical Analysis

Koel

2005

Critical Reviews in Analytical Chemistry

329

195

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Room-temperature ionic liquids are salts with a melting point close to or below room temperature. They form liquids composed in the majority of ions. This gives these materials the potential to behave very differently when they are used as solvents compared to conventional molecular liquids. The search for their application is growing in every area of analytical chemistryelectrochemistry, chromatography, electrophoresis, and even mass spectrometry. The literature on ionic liquids is growing almost exponentially. The basis for this activity is the easy preparation of salts with different ion constituents. This ability might best be described as the "chemical tunability" of ionic liquids, a class of solvents with members possessing similar physical properties but having different chemical behavior. Their good solvating properties, together with large spectral transparency, make ionic liquids suitable solvents for spectroscopic measurements. It has been demonstrated that task-specific ionic liquids have advantages compared to common solvents used as separation media in liquid-liquid extraction processes achieving high efficiencies and selectivities of separation. The main advantage for other applications of ionic liquids in analytical chemistry lies in their low volatility which makes them useful as solvents for working in both high-temperature (gas chromatography (GC) stationary phases) and high-vacuum (MALDI matrixes) environments. When using an ionic liquid as an electrolyte medium, it is possible to achieve a broader range of operational temperatures and conditions relative to other conventional electrolytic media, and this makes ionic liquids promising materials in various electrochemical devices (e.g., batteries, fuel cells, sensors, and electrochromic windows).

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Section: Liquid Chromatographymentioning

confidence: 99%

Ionic Liquids in Chemical Analysis

Koel

2005

Critical Reviews in Analytical Chemistry

329

195

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“…However, this explanation was only telling for basic compounds. Because the free silanols of the C 18 RP-HPLC column showed baseattracting and acid-repulsing effects, shielding of the free silanols by ionic liquids generally made basic compounds less retained whereas acid compounds more retained [15]. Therefore, for acid compounds, the mechanism for retention should be complicated.…”

Section: Effect Of the Alkyl Chain Length Of Ionic Liquids On The Retmentioning

confidence: 99%

“…4. For basic compounds, screening of the free silanols (b) by ionic liquid can make the analytes less retained [15]. With the increase of the concentration of ionic liquids, more free silanols were suppressed and thus the basic compounds became less retained; besides, repulsion between the imidazolium cations and the positively charged basic compounds also decreased the retention.…”

Section: Effect Of the Concentration Of Ionic Liquids On The Retentionmentioning

confidence: 99%

“…However, for acid compounds, the mechanism for separation and the effects of ionic liquids should be very different. According to Kaliszan et al [15] suppression of free silanols in the stationary phase by imidazolium tetrafluoroborate ionic liquids made basic compounds less retained whereas acid compounds more retained. Xiao et al [9] indicated the effect of ionic liquid on the separation of phthalic acids was very different from basic amines owing to the delocalization of the imidazolium cations.…”

Section: Introductionmentioning

confidence: 99%

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

Peng

Huang

et al. 2009

J of Separation Science

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In this present study, 1-butyl-3-methylimidazolium chloride ([C 4 MIM]Cl), 1-octyl-3-methylimidazolium chloride ([C 8 MIM]Cl), and 1-decyl-3-methylimidazolium chloride ([C 10 MIM]Cl) were adopted as mobile phase additives in the high performance liquid chromatography (HPLC) to simultaneously separate phenoxy acid herbicides and phenols at neutral pH. It was found that by using 20 mM of [C 4 MIM]Cl, baseline separation and good chromatograms for all the acid compounds were obtained on a normal reversedphase C 18 column. The retention time of the target acid compounds shortened with the increase of the alkyl chain length and the concentrations of ionic liquids, probably due to the delocalization of the positive charge on the imidazolium cation, the repulsion between chlorine ions of ionic liquids and the acid compounds, as well as the stereo-hindrance effect. The mechanism with ionic liquids as mobile additives for the separation of acid compounds was discussed.

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“…Interactions with free silanol groups can be reduced by different modifications of chromatographic systems, for example use of buffer solutions at acidic or basic pH, addition of ion-pairing reagents or silanol blockers to the mobile phase and selection of an appropriate stationary phase [22][23][24]. Good results are usually obtained in chromatographic systems containing addition of silanol blocking reagents, which have a cationic nature, and can interact with the stationary phase through two main mechanisms, which can take place simultaneously: direct electrostatic association with silanol sites, which blocks ion-exchange processes with solutes, and hydrophobic interaction with the alkyl-bonded stationary phase creating a charged bilayer.…”

Section: Introductionmentioning

confidence: 99%

Determination of some psychotropic drugs in human plasma by HPTLC

Wróblewski

Petruczynik

Waksmundzka‐Hajnos

2014

Acta Chromatographica

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Summary. Psychotropic drugs: desipramine, olanzapine and mitrazapine were chromatographed on cyanopropyl-silica and Diol-silica thin layers using various nonaqueous and aqueous eluents.The best results were obtained with addition of ammonia to nonaqueous eluent on both adsorbents. On the basis of the optimization, systems for extraction from human plasma and quantitative determination of investigated drugs were selected.RP18 encaped SPE columns conditioned and pre-eluted with acetonitrile:water: ammonium buffer at pH 8.6 (5:5:2) and eluted with methanol:water (9:1) containing 2% acetic acid were used for sample preparation with high recoveries of all investigated drugs. Diol and CN plates with mixture of 15% methanol in diisopropyl ether + 1% ammonia were used for quantitative analysis by a calibration curve method.

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Suppression of deleterious effects of free silanols in liquid chromatography by imidazolium tetrafluoroborate ionic liquids

Cited by 154 publications

References 24 publications

Ionic Liquids in Chemical Analysis

Ionic Liquids in Chemical Analysis

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

Determination of some psychotropic drugs in human plasma by HPTLC

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