Synthesis and characterization of polymeric C18 stationary phases for liquid chromatography

Sander, Lane C.; Wise, Stephen A.

doi:10.1021/ac00267a047

Cited by 347 publications

(188 citation statements)

References 28 publications

(37 reference statements)

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“…As can be expected, for all the stationary phases studied, the retention of pyrazines was deceased with increasing the content of organic solvent, MeOH or ACN, at constant column temperature, indicating that the dependence of the retention on the volume fraction of organic solvent in the mobile phase could be the same tendency as found in conventional RPLC separations. 4,5 Table 1 summarizes the calculated enthalpy of solute transfer from the mobile phase to an ODS stationary phase. Although all the analytes showed negative enthalpy of transfer from mobile phase to stationary phase with MeOH/water as the mobile phase, as can be expected from Fig.…”

Section: Resultsmentioning

confidence: 99%

“…The retention and separation mechanism of aromatic compounds including a variety of polycyclic aromatic hydrocarbons (PAHs) and pyrazines have been studied. [4][5][6][7][8][9][10][11][12][13][14][15][16][17] On the basis of actual retention measurements for pyrazines in several experimental conditions, a theoretical interpretation and the subsequent retention prediction were also studied in our previous work, 17 where the retention prediction models for pyrazine and alkylpyrazines were developed using multiple linear regression (MLR) and artificial neural networks (ANNs). During the study, the retention of these compounds was carefully determined in various conditions, including a variety of mobile phase conditions and column temperatures.…”

Section: Introductionmentioning

confidence: 99%

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An Abnormal Temperature Dependence of Alkylpyrazines’ Retention in Reversed-Phase Liquid Chromatography

et al. 2011

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Retention behaviors of pyrazine and alkylpyrazines on various stationary phases in reversed-phase liquid chromatography were examined. An abnormal temperature effect on the retention of alkylpyrazines with a mobile phase consisting of acetonitrile and water was observed when changing the column temperature. On the other hand, no similar trend was found with a methanol-water mobile phase. For all the columns investigated in this work, the above tendency to the temperature-dependence was consistently observed, suggesting that the abnormal temperature effect on the retention of alkylpyrazines could be mainly induced by an acetonitrile-based mobile phase.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

An Abnormal Temperature Dependence of Alkylpyrazines’ Retention in Reversed-Phase Liquid Chromatography

et al. 2011

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“…On the other hand, for silylation with multifunctional silanes, the heterogeneity due to the silanol distributions is reduced, and higher surface coverages (up to ~6.4 µmol/m 2 for silane polymerization in solution) can be achieved. 4,20 Nevertheless, surface heterogeneity arises from deposition and bonding of silane polymers onto the silica surface during synthesis; the silica surface may be covered with clusters of high ligand density, which would induce chain ordering. 8 We initially expected that the locally increased chain density of the DA-β-CD-bonded phase, compared to monomeric RPLC phases, would allow the chains to be more ordered, and therefore, to show enhanced solute shape selectivity.…”

Section: Resultsmentioning

confidence: 99%

An Attempt Directed toward Enhanced Shape Selectivity in Reversed-Phase Liquid Chromatography: Preparation of the Dodecylaminated β-Cyclodextrin-Bonded Phase

et al. 2002

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Soluteshape selectivity in reversed-phase liquid chromatography (RPLC) has been a topic of much study over the last decade.1,2 Several classes of closely related compounds, such as polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls, steroids, and carotenoids, can be separated in RPLC based on the molecular shape. 3 Although the contribution of the reversed-phase material to shape selectivity is not completely understood, there have been a few trends observed in RPLC separations. Shape selectivity varies with carbon loading of the stationary phase, the length of the alkyl-chains bonded to silica gel and the properties of the silica substrate. Also, it is well known that shape selectivity is enhanced by reducing the column temperature or by increasing the organic-modifier content in the mobile phase. Furthermore, shape selectivity differences are strongly influenced by the kind of surface-modification chemistry used. 4 It has been noted that polymeric octadecylsilane (ODS) silicas provide higher shape selectivity than monomeric counterparts in the separation of PAHs. [5][6][7] This has been ascribed to increased chain ordering in polymeric phases, which results from their alkyl chain organization as a result of higher chain densities. 4,6,[8][9][10][11][12] and simulation 13 studies have shown that chain ordering increases with increasing chain density.The purpose of this paper is to report on the synthesis of a new RPLC bonded phase that is designed so as to have regularly spaced, ordered chains on a local level. The possible structure of the prepared stationary phase is depicted in Fig. 1. A number of PAHs were separated with this stationary phase, and its selectivity was compared with those obtained with conventional stationary phases. The preliminary experiments revealed that the new stationary phase offers enhanced molecular shape-recognition performance.It may be noted that, by far, a large number of modified β-CD stationary phases have been synthesized, most of which were directed toward chiral separations, but not toward RPLC separations. An exception to this trend has been presented by i and Ishizuka. 14 They synthesized dodecylamino-β-CD by the reaction of heptakis(6-bromo-6-deoxy)-β-CD with dodecylamine in dimethylformamide. ODS silicas were coated with the produced material and used as a stationary phase for the separation of structural isomers. Experimental Synthesis of the stationary phaseThe preparation procedure of the stationary phase consisted of four separate stages (Fig. 2): (1) silylation of silica gel through reactions of 3-glycidoxypropyltrimethoxysilane with the surface silanol groups, 15 which provides a site for subsequent bonding with dodecylaminated β-CD; (2) sulfonation of the primary hydroxyl groups of β-CD with mesitylsulfonyl chloride, 16 (3) reaction of n-dodecylamine with mesitylenesulfonylated β-CD, yielding n-dodecylamino-derivatized β-CD (DA-β-CD) (the synthesis of heptakis(6-dodecylamino-6-deoxy)-β-CD has been already described by Takahashi et al. 17 ); and (4...

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“…Molecular ordering of the organic phase is also important for achieving a highly selective stationary phase. Although the selectivity of octadecyl silica (ODS) is mainly based on its hydrophobic distribution, dense octadecyl groups on silica increase the molecular shape selectivity of polyaromatic hydrocarbons (PAHs) and their isomers [10,11]. This selectivity improvement is explained by highly ordered alkyl chain conformation.…”

Section: Introductionmentioning

confidence: 99%

Effects of Alignment of Weak Interaction Sites in Molecular Shape Recognition High-Performance Liquid Chromatography

et al. 2016

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This paper introduces organic phases with aligned carbonyl groups derived from L-aspartic acid, L-glutamic acid, and L-α-aminoadipic acid; their stationary phases are denoted as Sil-Asp-2C n , Sil-Glu-2C n , and Sil-Adi-2C n , respectively. The stationary phases were used in high-performance liquid chromatography to investigate the alignment effect of carbonyl groups, which act as π-interaction sites, on molecular shape selectivity. The selectivities of the synthesized organic phases were evaluated using polyaromatic hydrocarbons (PAHs), including geometric isomers (e.g., cis-and trans-stilbenes). The PAH selectivities of the prepared stationary phases were higher than that of conventional octadecyl silica. Among the stationary phases prepared in this study, Sil-Glu-2C n (n = 18) showed the highest selectivity toward terphenyl isomers with different twist configurations and the lowest selectivity toward planar PAHs with different aspect ratios. The results show that the molecular shape selectivity of the phases was affected by the alignment of interaction sites. As a practical application of the octadecylated amino acid derivative-bonded stationary phases, we evaluated their selectivity for tocopherol isomers and achieved good separation. Furthermore, Sil-Asp-2C n (n = 1) showed hydrophilic interaction chromatography mode retention behavior for the separation of polar molecules like nucleosides.

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Synthesis and characterization of polymeric C18 stationary phases for liquid chromatography

Cited by 347 publications

References 28 publications

An Abnormal Temperature Dependence of Alkylpyrazines’ Retention in Reversed-Phase Liquid Chromatography

An Abnormal Temperature Dependence of Alkylpyrazines’ Retention in Reversed-Phase Liquid Chromatography

An Attempt Directed toward Enhanced Shape Selectivity in Reversed-Phase Liquid Chromatography: Preparation of the Dodecylaminated β-Cyclodextrin-Bonded Phase

Effects of Alignment of Weak Interaction Sites in Molecular Shape Recognition High-Performance Liquid Chromatography

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