Silanol effects in reversed-phase liquid chromatography

Welsch, Thomas; Frank, H.; Vigh, Gyula

doi:10.1016/s0021-9673(01)91570-5

Cited by 27 publications

(15 citation statements)

References 30 publications

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“…The use of 100% acetonitrile as mobile phase may be advantageous to our purpose, as acetonitrile solvates C18 alkyl chains rather well [33,34]. Solvation of the alkylsilane layer is assumed to facilitate access of solutes to residual silanol sites [11] and therefore eluents with a high acetonitrile content will show a RP-column's worst behavior towards basic analytes.…”

Section: Column Evaluation According To Waltersmentioning

confidence: 99%

“…Another issue of prime importance in stationary phase research is the influence of residual surface silanols (remaining after silylation of the silica substrate) on chromatographic column performance [9][10][11]. On one hand, residual silanols may be held responsible for unwanted phenomena like irreversible adsorption and peak tailing of basic solutes.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Chromatographic activity of residual silanols of alkylsilane derivatized silica surfaces

Scholten¹,

Claessens²,

Haan³

et al. 1997

Journal of Chromatography A

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Section: Column Evaluation According To Waltersmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Chromatographic activity of residual silanols of alkylsilane derivatized silica surfaces

Scholten¹,

Claessens²,

Haan³

et al. 1997

Journal of Chromatography A

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“…The practical usefulness of the RP-HPLC technique, however, seems to distract the chromatographer's attention from the theoretical problems that are left unsolved . For example, stationary phase stability and the relation between molecular stationary phase structure and chromatographic retention mechanism are still topics of discussion among stationary phase researchers. − Especially residual silanol functionalities, which remain at the silica surface after derivatization with alkylsilanes, have been the subject of investigation. − Apart from the solvophobic interactions between solutes and the nonpolar octadecyl phase, also the silanophilic interactions with residual silanols had to be taken into account to explain the observed chromatographic separation characteristics of silica-based alkylsilane phases.…”

Section: Introductionmentioning

confidence: 99%

Fundamental Study of Residual Silanol Populations on Alkylsilane-Derivatized Silica Surfaces

et al. 1996

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Two commercially available reversed phases for high-performance liquid chromatography (one dimethyl-n-octadecylsilane phase and one di-isobutyl-n-octadecylsilane phase) and the native silica substrate were subjected to deuterium exchange in a mobile phase-like medium of acetonitrile and deuterium oxide (90/10, v/v). 29Si cross-polarization magic-angle-spinning (CP MAS) NMR was used to obtain information on the amounts and relaxation behavior of the internal silanols of the silica substrate, and the residual silanols of the alkylsilane-derivatized phases. Consequences for the correlation of silanol 29Si CP MAS NMR data and chromatography are discussed. Detection of deuterated silanol (SiOD) signals in 29Si CP MAS NMR of deuterium-exchanged phases depends on a transfer of magnetization (cross-polarization) from silane protons to silanol silicon atoms. It is concluded that a large portion of the residual silanol NMR signal of the phases stems from internal silanols and from silanols that are spatially very close to an alkylsilane attachment site. The former are considered chromatographically irrelevant while the latter are assumed to be inaccessible for analytes during the chromatographic separation process for reasons of steric constraints. One bulky di-isobutyl-n-octadecylsilane is capable of cross-polarizing proton magnetization to 0.8 residual surface silanols, whereas this is only 0.3 for the conventional octadecylsilane with dimethyl side groups. However, the lower surface concentration of bulky alkylsilanes leaves more space for free, unhindered silanols. The most important factor determining the relaxation behavior of the residual silanol NMR signal is the mobility of the octadecylsilane side chains, bulky silanes having the larger mobility quenching effect on residual silanols.

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“…The active sites of the CSP responsible for the nonenantioselective HB interactions are unknown, and therefore no definitive conclusions concerning the HILIC separation mechanism can be drawn. It was reported in previous works that, although partially obstructed under a steric point of view, the residual silanol groups can impart undesirable effects during chromatographic resolution, especially towards basic analytes, because of their capability to establish secondary interactions and to induce significant peak tailing [18]. On the other hand, the same ACMPC is potentially able to create a typically hydrophilic environment, so that also the structure of the IG-3 CSP, as whole, can manifest a HILIC-like behavior, albeit to a limited extent.…”

Section: Analytical Hplc Enantioseparation Under Organic-aqueous Condmentioning

confidence: 99%

A chromatographic study on the retention behavior of the amylose tris(3‐chloro‐5‐methylphenylcarbamate) chiral stationary phase under aqueous conditions

Cirilli

Carradori

Casulli

et al. 2018

J of Separation Science

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In this study, the retention properties of the immobilized polysaccharide-derived Chiralpak IG-3 chiral stationary phase under aqueous-organic conditions were investigated. A systematic evaluation of the retention factors of the enantiomers of the chiral sulfoxide oxfendazole, endowed with anthelmintic activity and selected as test compound, was carried out changing progressively the water content in hydro-organic eluents containing methanol, ethanol or acetonitrile. From the results obtained with acetonitrile/water mobile phases and the associated retention plots, clear U-shape retention dependencies, indicative of the interplay of both hydrophilic interaction liquid chromatography and reversed-phase modes, were highlighted. A U-turn point of retention mechanism was recorded in correspondence of the acetonitrile/water 100:40 v/v mobile phase. Retention was significantly affected by small percentages of trifluoroacetic acid or diethylamine additives incorporated in the mobile phase. It is worth emphasizing that the basic additive was more effective in reducing retention in the reversed-phase region, while the action of acid additive was more pronounced in the hydrophilic interaction liquid chromatography region. Finally, either in the transition from hydrophilic interaction liquid chromatography to reversed-phase conditions or after additive addition, the enantioselectivity did not vary significantly.

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Silanol effects in reversed-phase liquid chromatography

Cited by 27 publications

References 30 publications

Chromatographic activity of residual silanols of alkylsilane derivatized silica surfaces

Chromatographic activity of residual silanols of alkylsilane derivatized silica surfaces

Fundamental Study of Residual Silanol Populations on Alkylsilane-Derivatized Silica Surfaces

A chromatographic study on the retention behavior of the amylose tris(3‐chloro‐5‐methylphenylcarbamate) chiral stationary phase under aqueous conditions

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