Chromatographic Behavior of Deoxyribonucleosides with Respect to Organic Modifier Content in the Mobile Phase

Journal of Liquid Chromatography & Related Technologies

2007

Four commonly known equations, two linear (Soczewinski and Langmuirtype) and two quadratic, have been applied for investigation of the influence of imidazolium ionic liquids modifiers on the retention eluent composition relationships in reversed-phase high performance liquid chromatography. In this study, three ionic liquids (1-butyl-3-methylimidazolium tetrafluoroborate, 1-ethyl-3-methylimidazolium methylsulfate, and 1-octyl-3-methylimidazolium methylsulfate) were evaluated as mobile phase modifiers. In the experiment, nine solutes belonging to three chemical classes, and namely: nucleic compounds (uridine 5 0 -monophosphate, inosine 5 0 -monophosphate, guanosine 5 0 -monophosphate, and hymidine 5 0 -monophosphate disodium salts), nitrogen containing heterocycles (guanine and hypoxanthine), and amino benzoic acids (orthro-, meta-, and para-isomers of amino benzoic acid) were tested. Evaluation of models of chromatographic retention was performed and discussed. The best correlations were achieved employing Langmuir-type and Soczewinski equations.

“…[17] This approach assumed that the adsorption of organic modifier is described by Langmuir isotherm. The final equation can be expressed as follows:…”

Section: Lagmuir Type Equationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Retention‐Eluent Composition Relationships of Some Polar Compounds with Imidazolium Ionic Liquid Modifiers in RP‐HPLC

Polyakova

Journal of Liquid Chromatography & Related Technologies

2007

“…[35] This approach assumed that the adsorption of organic modifier is described by the Langmuir isotherm. The final equation can be expressed as follows:…”

Section: Langmuir Type Equationmentioning

confidence: 99%

“…In the literature one can find complex models aimed at the prediction of changes in retention as a function of mobile phase composition. [32] Best known are: the Snyder model, [33,34] the Langmuir approach, [35] the solvatochromic model, [36] the stoichiometric displacement model, [37] the solvophobic model, [38] and the Schoenmakers model. [39] Many researchers investigated the separation of organic chemicals with different types of mobile phases and modifiers in RP-HPLC.…”

Section: Introductionmentioning

confidence: 99%

Analysis of Linear Regressions Applied to Water‐Methanol Eluents Modified with Ionic Liquid

Polyakova

Journal of Liquid Chromatography & Related Technologies

2007

Five equations, two linear (Soczewinski and Langmuir-type) and three multiple linear have been applied for investigation of the influence of 1-butyl-3-methylimidazolium tetrafluoroborate ionic liquid modifier on the retention eluent composition relationships in reversed-phase high performance liquid chromatography. In the experiment, five solutes belonging to amino acids, namely N-carbobenzyloxy-Dphenylalanine, D-tryptophan, and orthro-, meta-, and para-isomers of amino benzoic acid were tested. Statistical evaluation of models of chromatographic retention was performed and discussed. This study shows that Soczewinski and Langmuir-type equations are able to describe chromatographic retention of molecules which do not form stable ions in the aqueous, relatively precisely. At the same time, these models are not applicable for the description of N-CBZ-D-phenylalanine retention, which exists in the water solution as anion and more complex models, considering that interactions between ionizable sample and eluent are required. Multiple linear regressions with two variables (methanol and ionic liquid modifier contents) improve significantly the description of N-CBZ-D-phenylalanine retention.

“…To overcome this problem, Row et al proposed a Langmuir-type retention model. 5,6 It is important to predict the retention factors of solutes because the mobile phase composition is usually changed by the diluted content of organic modifier when gradient elution is used for the analysis. Many researchers have attempted to predict the retention time in gradient elution liquid chromatography.…”

Section: Introductionmentioning

confidence: 99%

Prediction of the Gradient Retention Times of Purine Compounds in Reversed Phase High Performance Liquid Chromatography

Lee

Journal of Liquid Chromatography & Related Technologies

2008

Self Cite

Various retention models have been developed and adopted to predict the retention behaviors of solutes in high performance liquid chromatography. Although the retention times can be successfully predicted in a gradient elution, it is difficult to predict the fundamental parameters of the eluted peaks, such as the number of theoretical plates, the resolution between neighboring peaks, as well as asymmetry factors. Thus far, the Snyder retention model has widely been used to predict the retention behavior in both isocratic and gradient conditions. However, it has a critical defect in that it cannot closely follow the retention behaviors of solutes when a relatively low content of organic modifier is used in the mobile phase. This is a result of the nonlinear relationship between the logarithm value of the retention factor and the volumetric percentage of organic modifier in the mobile phase. To overcome this shortcoming, a modified retention model was adopted to predict the retention times in several linear gradient conditions. A numerical method that transforms any gradient condition into discrete step gradient conditions was also proposed to predict the retention times in a gradient elution. The model is suitable to apply to nonlinear and multilinear gradient conditions, including actual obtained gradient profiles. Two kinds of organic modifiers, methanol and acetonitrile, were employed, and four purine compounds were used as solutes. The predicted retention times obtained by the modified retention model are in good agreement with experimental data in terms of the achieved gradient conditions.