Effect of the organic modifier concentration on the retention in reversed-phase liquid chromatography

Nikitas, P.; Pappa-Louisi, A.; Agrafiotou, P.

doi:10.1016/s0021-9673(01)01535-7

Cited by 67 publications

(33 citation statements)

References 44 publications

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“…Basically, Eq. (1) relies on the assumption that the analyte participates in the partition between mobile and stationary phase as a sole species, as not being involved in any secondary chemical equilibrium in mobile phase [17,18]. Deviation from van't Hoff temperature dependence of studied compounds can be explained by tautomeric interconversions in mobile phase in which they are participating.…”

Section: Data Modelingmentioning

confidence: 99%

Deviation from van't Hoff dependence in RP‐LC induced by tautomeric interconversion observed for four compounds

Galaon

David

2011

J of Separation Science

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The most encountered situations in reversed-phase liquid chromatography for temperature dependence of retention are those obeying the linear equation known as the van't Hoff plot. When studying compounds that are involved in structural modifications, it is likely that the temperature dependences of their retention factors do not follow this rule. It is the aim of this paper to report some particular cases when compounds involved in tautomeric interconversion have a different retention behavior with temperature: a deviation from the linearity of ln k on 1/T, or, in certain temperature ranges, temperature increase leading to a retention increase. Examples of compounds exhibiting deviation from the van't Hoff temperature dependence are piroxicam, drotaverine, vincamine, and epivincamine. A simple thermodynamic model relying on tautomeric equilibria in mobile phase is proposed for these compounds, which gives a polynomial dependence between ln k and 1/T.

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Section: Data Modelingmentioning

confidence: 99%

Deviation from van't Hoff dependence in RP‐LC induced by tautomeric interconversion observed for four compounds

Galaon

David

2011

J of Separation Science

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“…This is behavior that is opposite to that in RPLC and has characteristics typical of HILIC [28,52,53]. Perhaps, it might be a complex retention process composed of partitioning of solutes between a surface water layer and the bulk mobile phase, surface adsorption and electrostatic interactions [6,[54][55][56]. Hence, the retentive property at high levels of organic solvents reflected the hydrophilic nature of the stationary phase.…”

Section: The Effect Of Acetonitrile Content On Retentionmentioning

confidence: 96%

Stationary Phase Based on β-Cyclodextrin and Poly(N-isopropylacrylamide) for HILIC and RPLC

Zhu

Chen³

et al. 2015

Chromatographia

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highly polar and hydrophilic compounds are poorly retained on conventional reversed-phase stationary phases. Hydrophilic interaction chromatography (HILIC), as an increasingly important chromatographic mode, has been shown to be most useful for the analysis of highly polar and hydrophilic compounds [1][2][3][4][5]. It enjoyed nearly a decade of rapid growth in the early 2000s [6][7][8][9][10]. In HILIC, a mixture of water and a high percentage of organic modifiers (>65 %) is employed with a polar stationary phase [11][12][13][14][15]. Strongly polar compounds are sufficiently retained, for which HILIC offers different selectivity compared to the traditional RPLC [16][17][18]. Therefore, the analysis of highly hydrophilic and polar compounds by HILIC has been demonstrated as a powerful complementary approach to RPLC [19,20].Stationary phases for HILIC have received a lot of attention. Polar stationary phases are typically used to retain polar solutes in HILIC. In fact, most HILIC separations have been performed on normal phase columns commercially available mainly including bare-silica, amino-silica, cyano-and diol-silica, amide-silica, sulfoalkylbetaine bonded silica, carbohydrate-modified silica, triazol-bonded silica, and polymer-based monolithic columns [21][22][23][24][25][26]. Many new stationary phases and columns with a wide variety of functional groups have been developed exclusively for HILIC in recent years [27][28][29][30][31][32][33][34][35]. Moreover, more than one retention mechanism and the capability to be operated in different LC modes have been demonstrated [36][37][38][39][40][41][42]. Li et al.[43] developed a new stationary phase that combined both hydrophilic interaction and per aqueous liquid chromatography characteristics. The new phase consisted of carbon nanoparticles immobilized on the surface of porous silica particles. Ma et al. [44] successfully synthesized novel pH-responsive polymer-grafted silica whose hydrophilicity/hydrophobicity changed with pH. Shen et al. [45] Abstract A new stationary phase based on β-cyclodextrin and Poly(N-isopropylacrylamide) was prepared. The mass % of the polymer/100 g stationary phase was 23 %. Through investigating the effects of the acetonitrile (ACN) content of the mobile phase, the pH and the column temperature on the retention factor of polar and hydrophilic compounds in the ACN-rich mobile phase, it was found that the new stationary phase had the typical retention behavior of hydrophilic interaction liquid chromatography (HILIC). Moreover, the retention of solutes in the mobile phase exhibited "U-shaped" curves, which was an indication of HILIC/reversed-phase liquid chromatography (RPLC) mixed-mode retention behavior. In addition, the separation of some hydrophilic and different polar compounds was achieved by using the new material in HILIC and RPLC modes, respectively.

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“…Several three-parameter equations have been suggested by some investigators, such as those presented by Pappa-Louisi [21]: …”

Section: Theorymentioning

confidence: 99%

Optimization of the separation of chlorophenols with stepwise gradient elution in reversed phase liquid chromatography

Hadjmohammadi

Kamel

Fatemi

2007

J of Separation Science

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Short CommunicationOptimization of the separation of chlorophenols with stepwise gradient elution in reversed phase liquid chromatography An optimization technique based on gradient elution was used to separate eleven chlorophenols by reversed phase liquid chromatography. The separation was based on gradient elution with a stepwise variation pattern of the volume fraction of organic modifier, u, in the mobile phase. Initially, two-, three-, and four-parameter equations which describe the dependence of ln k9 upon u, were examined for their ability to fit the experimental data. It was found that, among these equations, the four-parameter equation gave the best fit of the experimental data. In addition to separation optimization, a non-linear least squares program with a grid search for initial estimates was used to determine the best variation pattern. The best variation pattern was obtained with u 1 = 0.27, u 2 = 0.39, u 3 = 0.62, t 1 = 33 min, and t 2 = 11 min. This pattern allowed the chromatographic separation of the chlorophenols with a good resolution and a total analysis time of 51 min. Good agreement was observed between predicted and experimental values of the retention times under optimal condition.

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Effect of the organic modifier concentration on the retention in reversed-phase liquid chromatography

Cited by 67 publications

References 44 publications

Deviation from van't Hoff dependence in RP‐LC induced by tautomeric interconversion observed for four compounds

Deviation from van't Hoff dependence in RP‐LC induced by tautomeric interconversion observed for four compounds

Stationary Phase Based on β-Cyclodextrin and Poly(N-isopropylacrylamide) for HILIC and RPLC

Optimization of the separation of chlorophenols with stepwise gradient elution in reversed phase liquid chromatography

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