Characterization of reversed-phase columns using the linear free energy relationship. III. Effect of the organic modifier and the mobile phase composition.

Retention factors determined for 31 solutes of widely different types on five columns of different chromatographic characteristics have been used to calculate the regression coefficients of the linear free energy relationship (LFER) equations. The mobile phases investigated consisted of acetonitrile-water and methanol-water, respectively, in a composition range of 20-70% (v/v) of organic modifiers. The regression coefficients of the LFER equations are characteristic of the given phase system (stationary phase, organic modifier and mobile phase composition) and represent the extent of the various molecular interactions contributing to the retention process. The effect of the characteristic of the stationary phase, the type of the organic modifier and the mobile phase composition is demonstrated and discussed. Alpha selectivity factors have been determined for various pairs of compounds. Hydrophobic or methylene selectivity can be described by the variation of the upsilon coefficient in Eq. (3) representing the difference in hydrophobicity between the stationary phase and the mobile phase. The polar or chemical selectivity of a phase system varies with the b coefficient in Eq. (3) representing the difference in acidity between the stationary phase and the mobile phase. Polar selectivity, i.e. the relative retention of polar solutes to that of a non-polar solute, e.g. toluene decreases with increasing polarity of the mobile phase. It depends also significantly on the polar characteristics of the columns. Specific selectivity, i.e. the relative retention of various polar solutes depends on the acidic or basic properties of the solutes to be separated and the chemical properties of the columns. The b regression coefficients can be used to describe the effect of mobile phase composition on the variation of specific selectivities. We have demonstrated that the LFER method provides a useful estimate of selectivity under different operating conditions by using the solvation parameters describing the different molecular interactions and the regression coefficients of the LFER equation characterizing the phase system.

[1]  R. Taft,et al.  The solvatochromic comparison method. I. The .beta.-scale of solvent hydrogen-bond acceptor (HBA) basicities , 1976 .

[2]  C. Hackett,et al.  Chromatographic classification of commercially available reverse-phase HPLC columns , 1997 .

[3]  A. Goldberg.  Comparison of columns for reversed-phase liquid chromatography , 1982 .

[4]  G. Guiochon,et al.  Effects of the bonded alkyl chain length on methylene selectivity in reversed-phase liquid chromatography , 1983 .

[5]  G. Guiochon,et al.  Interaction indexes for prediction of retention in reversed-phase liquid chromatography , 1982 .

[6]  Á. Sándi,et al.  Evaluation and modulation of selectivity in reversed-phase high-performance liquid chromatography , 1999 .

[7]  R. Taft,et al.  Study of retention processes in reversed-phase high-performance liquid chromatography by the use of the solvatochromic comparison method. , 1985, Analytical chemistry.

[8]  P. Jandera.  Method for chromaterization of selectivity in reversed-phase liquid chromatography , 1986 .

[9]  J. Park.  An Interpretation of Normal Phase Solvent Strength Scales Based on Linear Solvation Energy Relationships Using the Solvatochromic Parameters π , α and β , 1989 .

[10]  P. Carr,et al.  Global linear solvation energy relationships for retention prediction in reversed-phase liquid chromatography , 1999 .

[11]  Á. Sándi,et al.  Characterization of various reversed-phase columns using the linear free energy relationship: II. Evaluation of selectivity , 1998 .

[12]  H. Engelhardt,et al.  Chromatographic characterization of silica surfaces , 1981 .

[13]  P. Carr,et al.  Intermolecular interactions involved in solute retention on carbon media in reversed-phase high-performance liquid chromatography. , 1997, Analytical chemistry.

[14]  Michael H. Abraham,et al.  Linear solvation energy relationship. 46. An improved equation for correlation and prediction of octanol/water partition coefficients of organic nonelectrolytes (including strong hydrogen bond donor solutes) , 1988 .

[15]  P. Carr,et al.  Study of retention in reversed-phase liquid chromatography using linear solvation energy relationships , 1998 .

[16]  G. Guiochon,et al.  Linearity of homologous series retention plots in reversed-phase liquid chromatography , 1984 .

[17]  E. Bosch,et al.  Linear solvation energy relationships in reversed-phase liquid chromatography. Prediction of retention from a single solvent and a single solute parameter , 1993 .

[18]  M. Abraham,et al.  HYDROGEN BONDING. 42. CHARACTERIZATION OF REVERSED‐PHASE HIGH‐PERFORMANCE LIQUID CHROMATOGRAPHIC C18 STATIONARY PHASES , 1997 .

[19]  M. Jaroniec,et al.  Dependence of the methylene selectivity on the composition of hydro-organic eluents for reversed-phase liquid chromatographic systems with alkyl bonded phases , 1990 .

[20]  J. Chrétien,et al.  Factor analysis and experimental design in high-performance liquid chromatography : XI. Factor analysis maps and chromatographic information , 1991 .

[21]  M. Khaledi,et al.  Solvatochromic solvent polarity measurements and retention in reversed-phase liquid chromatography. , 1986, Analytical chemistry.

[22]  M. Abraham,et al.  Hydrogen bonding. 38. Effect of solute structure and mobile phase composition on reversed-phase high-performance liquid chromatographic capacity factors , 1994 .

[23]  R. Taft,et al.  Some observations regarding different retention properties of HPLC stationary phases , 1988 .

[24]  Michael H. Abraham,et al.  Linear solvation energy relationships. 23. A comprehensive collection of the solvatochromic parameters, .pi.*, .alpha., and .beta., and some methods for simplifying the generalized solvatochromic equation , 1983 .

[25]  M. Abraham,et al.  Hydrogen bonding: XXIII. Application of the new solvation equation to log Vg values for solutes on carbonaceous adsorbents , 1992 .

[26]  J. Tomaszewski,et al.  A comparison of eight commercial reverse-phase (ODS) columns for the separation of hydroxylated derivatives of 7,12-dimethylbenz(a)anthracene , 1983 .

[27]  C. Lochmueller,et al.  The effect of bonded chain rigidity on selectivity in reversed-phase liquid chromatography , 1985 .

[28]  S. Rutan,et al.  Solvatochromically based solvent-selectivity triangle , 1993 .

[29]  H. Engelhardt,et al.  Characterization of reversed phases by chemometric methods , 1991 .

[30]  L. R. Snyder,et al.  Classification of the solvent properties of common liquids , 1974 .

[31]  M. F. Burke,et al.  Comparison of stationary phase formation in RP- for methanol-water systems , 1982 .

[32]  L. Sander.  Evaluation of Column Performance in Liquid Chromatography , 1988 .

[33]  P. Carr,et al.  An approach to the concept of resolution optimization through changes in the effective chromatographic selectivity. , 1999, Analytical chemistry.

[34]  S. Wise,et al.  Determination of column selectivity toward polycyclic aromatic hydrocarbons , 1988 .

[35]  M. Abraham,et al.  Polyethylene-coated silica and zirconia stationary phases in view of quantitative structure-retention relationships , 1996 .

[36]  K. Jinno,et al.  Chromatographic Characterization of Silica C18 Packing Materials. Correlation between a Preparation Method and Retention Behavior of Stationary Phase , 1989 .

[37]  M. Khaledi,et al.  Solvatochromic solvent polarity measurements and selectivity in reversed-phase liquid chromatography. , 1987, Journal of chromatography.

[38]  N. Tanaka,et al.  Effect of stationary phase structure on retention and selectivity in reversed-phase liquid chromatography , 1982 .

[39]  Á. Sándi,et al.  Characterisation of wide-pore reversed phase columns for biopolymer separations. II. Multiparametric evaluation , 1997 .

[40]  T. Araki,et al.  Performance of wide-pore silica- and polymer-based packing materials in polypeptide separation: effect of pore size and alkyl chain length. , 1990, Journal of chromatography.

[41]  D. McCalley,et al.  Effect of organic solvent modifier and nature of solute on the performance of bonded silica reversed-phase columns for the analysis of strongly basic compounds by high-performance liquid chromatography , 1996 .

[42]  Paul Geladi,et al.  Principal Component Analysis , 1987, Comprehensive Chemometrics.

[43]  H. Schmidt,et al.  Properties and diversity of C18 bonded phases , 1982 .

[44]  Michael H. Abraham,et al.  Study of retention in reversed-phase liquid chromatography using linear solvation energy relationships. I. The stationary phase , 1996 .

[45]  S. Rutan,et al.  Re-evaluation of the solvent triangle and comparison to solvatochromic based scales of solvent strength and selectivity , 1989 .

[46]  P. Jandera.  A method for characterization and optimization of reversed-phase liquid chromatographic separations based on the retention behaviour in homologous series , 1984 .

[47]  M. Jungheim,et al.  Comparison and characterization of reversed phases , 1990 .

[48]  Michael H. Abraham,et al.  Hydrogen bonding. Part 34. The factors that influence the solubility of gases and vapours in water at 298 K, and a new method for its determination , 1994 .

[49]  B. Olsen,et al.  Chemometric categorization of octadecylsilyl bonded-phase silica columns using test mixtures and confirmation of results with pharmaceutical compound separations , 1995 .

[50]  G. Ahr,et al.  Properties of chemically bonded phases , 1981 .

[51]  N. Tanaka,et al.  Effect of alkyl chain length of the stationary phase on retention and selectivity in reversed-phase liquid chromatography , 1980 .

[52]  C. Cramers,et al.  Chromatographic and solid state nuclear magnetic resonance study of the changes in reversed-phase packings for high-performance liquid chromatography at different eluent compositions , 1988 .

[53]  C. Cramers,et al.  Influence of alkyl chain length on the stability of n-alkyl-modified reversed phases. 1. Chromatographic and physical analysis , 1990 .

[54]  A. Smilde,et al.  Multivariate characterization of solvent strength and solvent selectivity in reversed-phase high-performance liquid chromatography , 1991 .

[55]  J. Petersen,et al.  Simple preparation of a C8 HPLC stationary phase with an internal polar functional group , 1995 .

[56]  M. Abraham.  Application of solvation equations to chemical and biochemical processes , 1993 .

[57]  B. Karger,et al.  The role of organic modifiers on polar group selectivity in reversed-phase liquid chromatography , 1978 .

[58]  P. Jandera.  Reversed-phase liquid chromatography of homologous series : A general method for prediction of retention , 1984 .

[59]  R. Taft,et al.  Solute–solvent interactions in chemistry and biology. Part 7. An analysis of mobile phase effects on high pressure liquid chromatography capacity factors and relationships of the latter with octanol–water partition coefficients , 1988 .

[60]  P. Carr,et al.  Limitations of all empirical single-parameter solvent strength scales in reversed-phase liquid chromatography , 1989 .

[61]  C. Poole,et al.  Influence of fluorine substitution on the solvation properties of tetraalkylammonium alkanesulfonate phases in gas chromatography , 1992 .

[62]  R. Doherty,et al.  Hydrogen bonding : XV. A new characterisation of the McReynolds 77-stationary phase set , 1990 .

[63]  S. Wise,et al.  Shape selectivity in reversed-phase liquid chromatography for the separation of planar and non-planar solutes , 1993 .

[64]  M. Ericsson,et al.  Separation Properties of a Polymeric Octadecyl Silica Gel for Liquid Chromatography , 1986 .

[65]  M. F. Burke,et al.  Bonded phase conformation and salvation effects on the stationary phase structure in reversed-phase liquid chromatography , 1993 .

[66]  Á. Sándi,et al.  Characterization of various reversed-phase columns using the linear free energy relationship: II. Evaluation of selectivity , 1998 .

[67]  M. F. Burke,et al.  Investigation of stationary phase formation for RP-18 using various organic modifiers , 1982 .

[68]  Edmund R. Malinowski,et al.  Factor Analysis in Chemistry , 1980 .

[69]  Comparative study of hydrocarbon, fluorocarbon, and aromatic bonded RP-HPLC stationary phases by linear solvation energy relationships. , 1999 .

[70]  J. Dorsey,et al.  Retention mechanisms in reversed-phase chromatography. Stationary phase bonding density and solute selectivity. , 1989, Journal of chromatography.

[71]  L. Snyder,et al.  Combined use of temperature and solvent strength in reversed-phase gradient elution II. Comparing selectivity for different samples and systems , 1996 .

[72]  R. Doherty,et al.  Hydrogen bonding: XVII. The characterisation of 24 gas-liquid chromatographic stationary phases studied by Poole and co-workers. including molten salts, and evaluation of solute-stationary phase interactions , 1991 .

[73]  R. Taft,et al.  The solvatochromic comparison method. 2. The .alpha.-scale of solvent hydrogen-bond donor (HBD) acidities , 1976 .

[74]  Michael H. Abraham,et al.  Scales of solute hydrogen-bonding: their construction and application to physicochemical and biochemical processes , 2010 .

[75]  C. Poole,et al.  Interpretation of the influence of temperature on the solvation properties of gas chromatographic stationary phases using Abraham's solvation parameter model , 1993 .

[76]  P. Carr,et al.  Revisionist look at solvophobic driving forces in reversed-phase liquid chromatography: II. Partitioning vs. adsorption mechanism in monomeric alkyl bonded phase supports , 1997 .

[77]  H. Claessens,et al.  Characterization of wide-pore reversed-phase columns for biopolymer separations: I. Single-parametric evaluation , 1996 .

[78]  L. Snyder.  Classification off the Solvent Properties of Common Liquids , 1978 .

[79]  H. Engelhardt,et al.  Chromatographic characterization of silica-based reversed phases , 1991 .

[80]  T. Araki,et al.  Stationary phase effects in reversed-phase liquid chromatography , 1993 .

[81]  K. Unger,et al.  Packings and stationary phases for biopolymer separations by HPLC , 1987 .

[82]  R. Vervoort,et al.  Monitoring of new silica-based reversed-phase stationary phases for the liquid chromatographic analysis of basic pharmaceuticals using principal components analysis , 1997 .

[83]  J. Chrétien,et al.  Factor analysis and experiment design in high-performance liquid chromatography : X. Chemometric characterization of packings, solvents and solutes with hierarchical ascending classification and correspondence factor analysis , 1991 .

[84]  L. Snyder,et al.  Characterization of silica-based reversed-phase columns with respect to retention selectivity : Solvophobic effects , 1985 .

[85]  J. Dorsey,et al.  Retention mechanisms in reversed-phase liquid chromatography. Stationary-phase bonding density and partitioning. , 1989, Analytical chemistry.

[86]  H. P. Jung,et al.  Characterization of some silica-based reversed-phase liquid chromatographic columns based on linear salvation energy relationships , 1994 .

[87]  D. McCalley,et al.  Influence of organic solvent modifier and solvent strenght on peak shape of some basic compounds in high-performance liquid chromatography using a reversed-phase column☆ , 1995 .

[88]  K. Sentell,et al.  Temperature and solvation effects on homologous series selectivity in reversed phase liquid chromatography , 1995 .

[89]  Á. Sándi,et al.  Characterization of different RP-HPLC columns by a gradient elution technique , 1997 .

[90]  C. Cramers,et al.  Statistical evaluation of the validity of a method for characterizing stationary phases for reversed-phase liquid chromatography based on retention of homologous series , 1994 .

[91]  R. Taft,et al.  Study of temperature and mobile-phase effects in reversed-phase high-performance liquid chromatography by the use of the solvatochromic comparison method. , 1986, Analytical chemistry.