Evaluation and modulation of selectivity in reversed-phase high-performance liquid chromatography

Sándi, Ákos; Szepesy, L.

doi:10.1016/s0021-9673(99)00361-1

Cited by 53 publications

(31 citation statements)

References 34 publications

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“…Moreover, the elution-order of these HCAs on the Cu-PCSD-TMCS column is different from those on the Cu-PCSD and Cu-PCSD-TMSI. These results indicate that the HCAs interact strongly with the remaining amino-groups on the Cu-PCSD through such electrostatic interactions as the dipole-dipole interaction 18 and hydrogen bonding 19 in addition to the π-π interaction. We then used pure methanol as the mobile phase in order to decrease the electrostatic interactions.…”

Section: Separation Of Hcasmentioning

confidence: 87%

Effects of Trimethylsilylation of Copper(II)-Phthalocyanine Sulfonyl-Aminopropyl Silica Gels on the Separation of π-Electron-Rich Compounds by High-Performance Liquid Chromatography

et al. 2001

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We have demonstrated in our previous studies [1][2][3] that commercially available aminopropyl-silica gels for HPLC could be converted into functional silica gels exhibiting the π-π electron interaction by a modification with metalphthalocyanine derivatives. In particular, silica gels modified with the Cu-PCS derivative (Cu-PCSD) 3 have proved to be a superior HPLC stationary phase for the separation of π-electronrich compounds compared to pyrenylethyl-silica gels 4,5 or silica gels binding porphine and metal-porphines. 6,7 However, Cu-PCSD is still unsatisfactory regarding the theoretical plate numbers (N) for some PAHs. 3 In this study, we assumed that the small N values in the previous paper were caused by an electrostatic interaction 8,9 between the solutes and the polar groups remaining on Cu-PCSD. As an attempt to elucidate the factor(s) responsible for the poor performance of the Cu-PCSD column, we tried to decrease the polarity of the silanol and/or amino groups by endcapping them with trimethylsilyl groups. This treatment resulted in an improvement of not only the N values, but also the efficiency of the separations of PAHs, thereby increasing the performance of the Cu-PCSD column. This improvement would be attributable to a decrease in the electrostatic interaction and also partly to an additional hydrophobic interaction between the trimethylsilyl-groups and the PAHs. The retention behaviors of hetrocyclic amines (HCAs), typical mutagens, 10 on the Cu-PCSD column were also changed after trimethylsilylation. Experimental Reagents Silica gels.As aminopropyl-silica gels, Develosil NH2-5 (Dev, particle size, 5 µm; specific surface area, 350 m 2 /g; average pore size, 120 Å) were purchased from Nomura Chemicals Co. Ltd. and dried at 150˚C for 2 h under a vacuum. Chemicals and reagents.Copper-phthalocyanine (Cu-PC, Fig. 1) was obtained from a commercial source (Kanto Kagaku Co. Ltd.) for the preparation of copper-phthalocyanine tetrasulfonylchloride (Cu-PCSCl, Fig. 1). Methanol used as mobile phases was of special-grade for HPLC. Special-grade dioxane was dried with molecular sieves and used for preparing modified silica gels. Trimethylchlorosilane (TMCS) and Ntrimethylsilylimidazole (TMSI) were purchased from GL Sciences Inc. Samples.π-Electron rich PAHs, benzene, naphthalene, As an attempt to elucidate the factor(s) responsible for the poor performance of a copper(II)-phthalocyanine aminopropylsilica gels (Cu-PCSD) column for HPLC, the silanol and/or amino groups remaining on Cu-PCSD were endcapped with trimethylchlorosilane (TMCS) or N-trimethylsilylimidazole (TMSI). The trimethylsilylated Cu-PCSDs (Cu-PCSD-TMCS and -TMSI) were investigated concerning their performance as an HPLC-stationary phase in the separation of π-electronrich polyaromatic hydrocarbons (PAHs), such as mutagenic anthracene and pyrene. As a result, trimethylsilylation with TMSI, which reacts only with silanol-groups, was not effective to improve the column efficiency. In contrast, trimethylsilylation by TMCS, which reacts with both t...

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Section: Separation Of Hcasmentioning

confidence: 87%

Effects of Trimethylsilylation of Copper(II)-Phthalocyanine Sulfonyl-Aminopropyl Silica Gels on the Separation of π-Electron-Rich Compounds by High-Performance Liquid Chromatography

et al. 2001

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“…For the selection of the best column the selectivity is the most important factor influencing chromatographic separation. Chromatographic selectivity or selectivity factor a is an important experimental probe in the characterization of stationary phases [64,65,79,81]. The overall (or measured) selectivity comprises the combined effects of several different mechanisms because of the different types of molecular interactions involved in the retention process.…”

Section: Selectivitymentioning

confidence: 99%

“…The overall (or measured) selectivity comprises the combined effects of several different mechanisms because of the different types of molecular interactions involved in the retention process. In order to take into account the effect of the different types of interactions, we have defined and used different selectivities in the comparison of stationary phases [79,81,90].…”

Section: Selectivitymentioning

confidence: 99%

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Evaluation of column characteristics in RPLC using linear solvation energy relationships (LSERs)

Szepesy¹

2003

J of Separation Science

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Evaluation of column characteristics in RPLC using linear solvation energy relationships (LSERs)An overview is given of our studies on the use of linear solvation energy relationships (LSERs) for evaluation and comparison of RP-HPLC columns. From among the columns investigated, 19 columns of different types, viz. 12 narrow-pore, 7 wide-pore silicas containing various ligands (C18, C8, C4, CN) and obtained from 7 manufacturers, were compared and evaluated. Retention factors of 32 solutes of widely differing chemical properties were measured and evaluated to determine the effect of stationary phase properties on the retention of various types of solutes. When the same mobile phase is used with the different columns, the regression coefficients determined by multivariate regression characterize the various stationary phases. The columns investigated were evaluated on the basis of the relative importance of the various types of interactions reflecting the various surface properties of the stationary phases. Since the selectivity of separation is more important than is absolute selectivity, we have investigated and compared the various selectivity terms, hydrophobic, polar, and specific selectivity, displayed by the various columns, for the separation of different types of compounds. As the selectivity of separation depends also on the type and composition of the mobile phase, the effect of mobile phase on the various selectivity terms was evaluated.

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“…Typical values of retention factor of the solutes should be in the range 1-10 and values of resolution greater than 1.5 when quantitative analysis to be performed. Separation selectivity can be varied with type of the stationary and the mobile phases (Szepesy 2002;Lavine et al 2002;Sandi and Szepesy 1999). However, the simplest way leading very often to a variation of separation selectivity of solutes is based on alteration of composition of the mobile phase including concentration and type of a modifier (organic component of the mobile phase) and pH of buffer.…”

Section: Introductionmentioning

confidence: 99%

Separation selectivity of some phenolic acids in RP HPLC systems with binary mobile phase comprised various modifiers

Klimek-Turek

Dzido

2010

Adsorption

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Retention of phenolic acid has been correlated for reversed-phase high-performance liquid chromatography systems with different binary mobile phases containing methanol, acetonitrile or tetrahydrofuran as modifiers and buffer at pH 3.0, 4.6 and 5.0. The changes of separation selectivity of solutes, when one modifier is replaced by another in the eluent, has been explained taking into consideration molecular interactions of the solutes with components of the stationary phase region, i.e. extracted modifier, and ordering of the stationary phase by the modifier.Keywords Modifier selectivity · Mechanism of separation selectivity in reversed phase liquid chromatography · Phenolic acids

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Evaluation and modulation of selectivity in reversed-phase high-performance liquid chromatography

Cited by 53 publications

References 34 publications

Effects of Trimethylsilylation of Copper(II)-Phthalocyanine Sulfonyl-Aminopropyl Silica Gels on the Separation of π-Electron-Rich Compounds by High-Performance Liquid Chromatography

Effects of Trimethylsilylation of Copper(II)-Phthalocyanine Sulfonyl-Aminopropyl Silica Gels on the Separation of π-Electron-Rich Compounds by High-Performance Liquid Chromatography

Evaluation of column characteristics in RPLC using linear solvation energy relationships (LSERs)

Separation selectivity of some phenolic acids in RP HPLC systems with binary mobile phase comprised various modifiers

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