Effect of some amines on the ionic, dipolar, and hydrogen bonding interactions between test solutes and support in reversed-phase liquid chromatography

Tramposch, Walter G.; Weber, Stephen G.

doi:10.1021/ac00277a066

Cited by 17 publications

(2 citation statements)

References 48 publications

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“…(only ionic strength effect). On SAS Hypersil, the "salting-out" effect seems to be less important, and ion exchange phenomena, enhanced by NaCl (25)(26)(27), can occur with surface silanols. The silanols have much greater affinity for CTA+ than for Na+ (28) and no affinity for anionic SDS.…”

Section: Resultsmentioning

confidence: 99%

Additive effects on surfactant adsorption and ionic solute retention in micellar liquid chromatography

Berthod¹,

Girard²,

Gonnet³

1986

Anal. Chem.

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Section: Resultsmentioning

confidence: 99%

Additive effects on surfactant adsorption and ionic solute retention in micellar liquid chromatography

Berthod¹,

Girard²,

Gonnet³

1986

Anal. Chem.

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“…There are, however, several findings showing that this simple model does not take into account the intrinsic complexity of RP chromatography. For instance, it has been reported by many authors that polar compounds, under certain conditions, − exhibit a characteristic U-shaped retention profile: by increasing the organic modifier (very often acetonitrile) in the mobile phase, their retention decreases only up to a certain point where, at organic-rich eluents, it begins to increase. The point of minimum retention is however unpredictable a priori and changes with the characteristics of adsorbent–eluent system.…”

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confidence: 99%

Understanding Mixed-Mode Retention Mechanisms in Liquid Chromatography with Hydrophobic Stationary Phases

et al. 2014

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The chromatographic retention mechanisms of two hydrophobic bonded phases, octadecyl ethyl-bridged organic/inorganic (BEH-C18) and straight-chain perfluorohexylpropyl silica (C6F13), have been investigated by using a homologous series of alkyl-benzenes and perfluoroalkyl acids as test compounds in a variety of acetonitrile/water mobile phases and at different temperatures. On both columns, polar compounds exhibited a characteristic U-shape retention behavior in function of acetonitrile amount in the eluent, whereas retention of neutral molecules decreased continuously, following an increase of organic modifier, over the entire mobile phase range. The dependence of perfluoromethylene selectivity upon eluent composition explains the typical reversed-phase behavior (decreasing in retention following an increase of acetonitrile in mobile phase) initially exhibited by perfluoroalkyl acids, but alone it cannot justify their increasing of retention at organic-rich mobile phases (approximately >90% v/v for acetonitrile with the C6F13 column and acetonitrile >80% v/v for the BEH-C18 one). It actually predicts an opposite trend, indicating thus the presence of mixed-mode retention mechanisms. Indeed it was found that, at organic-rich mobile phases, the transfer from the mobile to the stationary phase of the polar moiety of molecules drives retention. This finding has been correlated to the excess adsorption isotherm of acetonitrile/water binary mixtures and thus to the composition of the stationary phase. At organic-rich mobile phases, in fact, stationary phases are characterized by a positive excess of adsorbed water that creates an "environment" suitable to the transfer herein of polar groups.

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The use of silica for liquid chromatographic/mass spectrometric analysis of basic analytes

McKeown

Euerby²,

Lomax

et al. 2001

J. Sep. Science

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Silica stationary phases of varying purity have been compared and evaluated for the LC separation of pharmaceutically relevant basic compounds of differing molecular weight, log P, and pKa using aqueous/organic mobile phases. The least pure silica gave the best separations. All phases showed a linear relationship between ln k and volume fraction of ACN (30–70%) or MeOH (15–35%). The investigations confirmed that all the unbonded phases examined possessed a hydrophobic/adsorption and ion‐exchange character. The use of silica with MS “friendly” mobile phases, and high volume fractions of ACN, has been shown to be applicable to LC/MS analysis of basic analytes.

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Effect of some amines on the ionic, dipolar, and hydrogen bonding interactions between test solutes and support in reversed-phase liquid chromatography

Cited by 17 publications

References 48 publications

Additive effects on surfactant adsorption and ionic solute retention in micellar liquid chromatography

Additive effects on surfactant adsorption and ionic solute retention in micellar liquid chromatography

Understanding Mixed-Mode Retention Mechanisms in Liquid Chromatography with Hydrophobic Stationary Phases

The use of silica for liquid chromatographic/mass spectrometric analysis of basic analytes

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