Essentials in Modern HPLC Separations

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Front-Matter_2022_Essentials-in-Modern-HPLC-Separations Essentials in Modern HPLC Separations Preface_2022_Essentials-in-Modern-HPLC-Separations Preface Chapter-1---Introductory-information-rega_2022_Essentials-in-Modern-HPLC-Sep 1. Introductory information regarding HPLC 1.1 Preliminary discussion about HPLC General comments What is chromatography and what is HPLC? Types of equilibria in HPLC Role of polarity in HPLC Applications of HPLC in chemical analysis Nonanalytical applications of analytical HPLC 1.2 Main types of HPLC Criteria for the classification of HPLC procedures A classification of HPLC types based on the nature of stationary and mobile phase Relation between the type of HPLC, equilibrium type, and molecular interactions 1.3 Flow of a typical HPLC analysis General aspects Selection of the type of HPLC for a particular application Sample collection and sample preparation for HPLC References Chapter-2---Overview-of-HPLC-instrumentatio_2022_Essentials-in-Modern-HPLC-S 2. Overview of HPLC instrumentation and its use 2.1 Description of main components of HPLC instrumentation General comments Description of a typical HPLC instrument Solvent supply system Pumping systems Tubing and connectors Injectors and autosamplers Column holders Chromatographic columns General comments regarding detectors UV-Vis spectrometric detectors Fluorescence and chemiluminescence detectors Refractive index detectors Electrochemical detectors Mass spectrometric detectors Evaporative light-scattering detectors Other types of detectors Selection of a detector in HPLC Other devices that can be part of the HPLC system More complex or special HPLC setups Instrument control and data processing unit Selection of the HPLC system and transition from HPLC to UPLC References Chapter-3---Parameters-for-the-characterizati_2022_Essentials-in-Modern-HPLC 3. Parameters for the characterization of HPLC separation 3.1 Parameters describing the chromatographic peak General aspects Flow rate of the mobile phase Retention time Run time Retention volume Migration rate Equilibrium constant and phase ratio in HPLC separations Retention factor General equation of solute retention Characteristics of an ideal peak shape in chromatography Efficiency of a chromatographic column Factors contributing to peak broadening and van Deemter equation Application of van Deemter equation Peak asymmetry Statistical moments for the description of peak characteristics Peak characterization using exponentially modified Gaussian shape 3.2 Parameters describing the separation General aspects Selectivity (separation factor) Resolution Peak capacity 3.3 Summary of chromatographic peak and separation characteristics General comments 3.4 Parameters related to quantitation in HPLC General comments Quantitation parameters from the chromatographic peak Sample volume and amount injected in the chromatographic column Limit of detection in HPLC Limit of quantitation 3.5 Parameters characterizing the gradient separation General comments Retention factor in gradient separations Other parameters for the characterization of chromatograms in gradient separations References Chapter-4---Equilibrium-types-in-HP_2022_Essentials-in-Modern-HPLC-Separatio 4. Equilibrium types in HPLC 4.1 Partition equilibrium General comments Liquid–liquid partition Dependence of retention factor on mobile phase composition in partition chromatography Distribution coefficient Peak shape in partition chromatography Evaluation of retention factor from liquid–liquid distribution constants 4.2 Adsorption equilibrium Liquid–solid equilibrium Dependence of retention factor on mobile phase composition in adsorption equilibrium Peak shape in adsorption chromatography 4.3 Equilibrium involving ions General aspects Retention equilibrium involving ions Equilibrium of ions in the presence of a complexing reagent 4.4 Equilibrium in size exclusion processes General aspects Equilibrium between interstitial mobile phase and pore mobile phase 4.5 The influence of pH and of additives on retention equilibria Preliminary information about pH Dependence of compound structure on pH The influence of pH on partition equilibrium Dependence on pH of octanol/water distribution coefficient Dow Influence on separation of additives not involved in the equilibrium Chaotropic salts influence on equilibria 4.6 The influence of temperature on retention equilibrium General aspects Evaluation of thermodynamic parameters of a separation from van't Hoff plots Nonlinear dependence of the retention factor on 1/T Evaluation of enthalpy–entropy compensation from van't Hoff plots High-temperature HPLC 4.7 Reactions occurring in HPLC column General comments Enantiomerization and diastereomerization Tautomerism References Chapter-5---Intermolecular-interacti_2022_Essentials-in-Modern-HPLC-Separati 5. Intermolecular interactions 5.1 Forces between molecules General comments Charge to charge interactions Energy of an ion in a continuous medium Polar molecules Ion to dipole interactions Dipole to dipole interactions Polarizability of molecules Ion to molecule interactions Dipole to molecule interactions Nonpolar molecule to molecule interactions Unified view of interactions in the absence of ions Lennard–Jones potential Hydrogen bond interactions Charge transfer or donor–acceptor interactions Stacking and inclusion in supermolecular systems Other types of bonds The effect of a solvent on molecular interactions Solvophobic effects Chaotropic and kosmotropic interactions 5.2 Forces between molecules and a charged surface General comments Charge to charged-surface interactions Neutral molecule to charged-surface interactions References Chapter-6---Characterization-of-analytes-a_2022_Essentials-in-Modern-HPLC-Se 6. Characterization of analytes and matrices 6.1 Properties of solutes important for HPLC separation Solutes classification based on their chemical structure Classification based on the role of the analyte in everyday life Comments on physico-chemical properties of analytes and matrices Molecular weight Acidic or basic character of analytes van der Waals molecular volume and area Molecular shape Molar volume Molecular polarity Partial charge distribution Isoelectric point Octanol/water partition constant and its use for polarity estimation Thermodynamic parameters related to solubility of nonelectrolyte compounds Activity coefficient from enthalpy of mixing Solubility in water from octanol/water partition constant Correlation between van der Waals molecular surface and octanol/water partition constant Solvatochromic parameters for solute characterization Other parameters for solute characterization 6.2 Physico-chemical properties related to detection General comments Gas-phase acidity and basicity in MS process of ion formation The role of analyte polarity in MS detection 6.3 Properties of matrix related to HPLC separation and detection General comments Matrix effects on the separation in HPLC Matrix effects on HPLC detection References Chapter-7---Mobile-phases-and-their-pro_2022_Essentials-in-Modern-HPLC-Separ 7. Mobile phases and their properties 7.1 Characterization of liquids as eluents in HPLC General comments Characterization of solvents with Hildebrand solubility parameter Miscibility of solvents and solubility one in another Solvent characterization using octanol/water partition constant Kow Solvent characterization based on liquid–gas partition Solvatochromic model and Kamlet–Taft parameters Eluotropic strength Solvent characterization based on other parameters Solvent properties of liquid mixtures 7.2 Additional physical properties of liquids affecting separation General comments Solvent density, viscosity, and diffusion coefficient Surface tension Dielectric constant, dipole moment, and polarizability Hydrogen bonding of solvent molecules Solvent boiling point 7.3 Properties of liquids affecting HPLC detection General comments Refractive index UV cut-off Fluorescence Solvent influence in MS detection Solvent properties related to other detection techniques 7.4 Buffers and additives General comments Buffer pH Buffer capacity Common buffers used in HPLC Buffers in partially aqueous solvent mixtures The influence of temperature on the pH of buffers Solubility of buffers in partially organic mobile phases Additives Influence of buffers and additives on column stability and properties Suitability of buffers and additives for the detection in HPLC 7.5 General use of solvents as mobile phase General comments Solvent purity in HPLC Flow rate, temperature, and degassing of mobile phase The use of “green” solvents as mobile phase in HPLC 7.6 Solvents for sample injection and for needle wash General comments The role of sample solvent in the chromatographic process Effect of sample solvent on detection Solvents for the needle wash 7.7 Gradient elution General comments Gradient of solvent composition Gradient of pH or of additive concentration Gradient in flow rate Gradient in separation temperature Usefulness of gradient vs. isocratic elution References Chapter-8---Analytical-HPLC-columns-and-thei_2022_Essentials-in-Modern-HPLC- 8. Analytical HPLC columns and their characteristics 8.1 Construction of an HPLC column General comments External body of the column Packing of particles in the chromatographic column Physical characteristics of the solid supports for the packed columns Chemical characteristics of the solid supports for the packed columns Silica and ethylene-bridged silica as solid support for the stationary phase Silica-based monolithic chromatographic columns Core-shell particles in packed columns Hydride-based silica Other inorganic support materials Porous graphitic carbon and other carbon-based materials Organic polymers used as support for stationary phases Derivatization of silica solid support Direct synthesis of silica materials with an active bonded phase surface Derivatization of silica hydride supports Derivatization of presynthesized organic polymers Synthesis of organic polymers with active groups Synthesis of organic polymeric monoliths with active functionalities Coated or immobilized (grafted) polymeric stationary phases on silica Metal-organic frameworks used as stationary phase for HPLC 8.2 Column properties affecting separation General comments Dimensions of the column body affecting separation Physical properties of stationary phase affecting separation Chemical characteristics of stationary phase affecting separation Octanol/water distribution constant used to describe polarity of the active groups in the stationary phase 8.3 Selection of a column for an HPLC separation General comments The use of guard columns and cartridges Column protection, cleaning, regeneration, and storing Selection of columns for orthogonal separations References Chapter-9---Reversed-phase-HPLC_2022_Essentials-in-Modern-HPLC-Separations 9. Reversed-phase HPLC 9.1 Retention and elution process in RP-HPLC General comments Retention/elution in RP-HPLC Equilibrium type in RP-HPLC separation Molecular interactions in RP-HPLC Retention results based on molecular interactions evaluation Other interactions affecting RP-HPLC separations 9.2 Stationary phases and columns for RP-HPLC General comments Specific procedures for the synthesis of stationary phases in RP-HPLC Basic physical properties of hydrophobic stationary phases and columns Basic chemical characteristics of RP-type stationary phases Advances in the construction of common RP-columns Availability of special types of hydrophobic columns 9.3 Parameters used for the characterization of RP-HPLC phases and columns General comments Efficiency of columns (theoretical plate number) Retention capability of columns used in RP-HPLC Methylene selectivity and general selectivity for hydrophobic columns Peak asymmetry for RP-HPLC columns Hydrophobic subtraction model for selectivity characterization Various other parameters and tests for RP-HPLC column characterization Tests for the evaluation of aging of the chromatographic column 9.4 Selection of the column in RP-HPLC General comments Sample nature in RP-HPLC and its influence on column selection Column choice from several possibilities 9.5 Mobile phases in reversed-phase liquid chromatography General comments Water and mobile phases with high water content Alcohols used in mobile phase Acetonitrile Other solvents used in RP-HPLC 9.6 Selection of mobile phase in RP-HPLC General comments 9.7 Prediction of parameters describing the separation in RP-HPLC General comments Estimation of retention factor k′ for similar systems at different mobile phase compositions Evaluation of retention factor k′ from octanol/water partition constants Kow or Dow Calculation of retention factor from van der Waals molecular surface of the analyte Prediction of log k′ based on solute, mobile phase, and stationary phase characteristics Evaluation of the energies of interaction in the separation system Other approaches References Chapter-10---Other-HPLC-separations-performed-on_2022_Essentials-in-Modern-H 10. Other HPLC separations performed on hydrophobic stationary phases 10.1 Nonaqueous RP-HPLC General comments Mobile phase composition in NARP Utility of NARP compared to RP-HPLC 10.2 Ion pair liquid chromatography General comments Ion-pairing mechanisms Partition model in IP Electrostatic model in IP Stationary phases in ion pair chromatography Mobile phase in ion pair chromatography Chaotropes in ion pairing 10.3 Hydrophobic interaction chromatography (HIC) General comments Retention mechanism in HIC 10.4 Micellar, microemulsion, and other types of HPLC performed on hydrophobic phases Micellar liquid chromatography Microemulsion liquid chromatography Other liquid chromatography types on hydrophobic phases References Chapter-11---Hydrophilic-interaction-liquid_2022_Essentials-in-Modern-HPLC-S 11. Hydrophilic interaction liquid chromatography 11.1 Retention and elution process in HILIC General comments Equilibrium type for retention/elution in HILIC Description of molecular interactions in HILIC Retention results based on molecular interactions in HILIC 11.2 Polar stationary phases and columns General comments Specific procedures for the synthesis of polar phases Physical properties of polar stationary phases and columns Chemical characteristics of polar stationary phases Bare silica stationary phases HILIC stationary phases with a bonded surface Silica hydride–based phases Advances in the construction of HILIC columns 11.3 Retention and separation properties of polar stationary phases General comments Parameters and tests for HILIC column characterization 11.4 Selection of the column in HILIC separations General comments Selection of the nature of stationary phase for the column Selection of physical column characteristics in HILIC Other parameters important in HILIC column selection 11.5 Mobile phase in HILIC General comments Double role of the mobile phase in HILIC The gradient elution in HILIC separations Ion-pairing additives for HILIC separations Influence of mobile phase on detection in HILIC 11.6 Prediction of parameters describing the separation in HILIC General comments Estimation of retention factor k′ for similar systems at different mobile phase compositions Other estimation procedures for HILIC parameters References Chapter-12---Other-HPLC-separations-performed-o_2022_Essentials-in-Modern-HP 12. Other HPLC separations performed on polar stationary phases 12.1 Normal phase liquid chromatography General comments NPC compared to HILIC Mobile phase in NPC 12.2 Other chromatographic techniques based on polar interactions Aqueous normal phase liquid chromatography Electrostatic repulsion hydrophilic interaction chromatography References Chapter-13---Ion-exchange--ion-moderated--and-lig_2022_Essentials-in-Modern- 13. Ion exchange, ion-moderated, and ligand exchange liquid chromatography 13.1 Retention and elution in ion exchange liquid chromatography General comments Retention/elution in ion exchange chromatography Separation in ion chromatography Retention of neutral molecules on ion exchange phases Retention in ion-moderated chromatography Retention in ligand exchange and immobilized metal affinity chromatography Ion exclusion 13.2 Stationary phases and columns for ion exchange and related HPLC techniques Types of ion exchange phases Ion-moderated and ligand exchange phases Summary of procedures for the synthesis of ion exchange phases Latex-agglomerated ion exchangers Cation exchange phases based on silica Organic polymeric cation exchange phases Anion exchange phases based on silica Organic polymeric anion exchange phases Zwitterionic stationary phases Capillary IC columns Other IC stationary phases 13.3 Characterization of ion exchange stationary phases General comments Ionic loading capacity measurement Solvent compatibility of ionic phases Phase affinity for specific ions Hydrophobicity of IC columns 13.4 Selection of an ion exchange stationary phase General comments Separation of small ions by IC Separation of ionic organic molecules Separation of neutral organic molecules Separation of proteins and nucleic acids 13.5 Mobile phase in ion exchange and ion-moderated liquid chromatography General comments Mobile phase in cation exchange chromatography Mobile phase in anion exchange chromatography Gradient elution in ion chromatography Chromatofocusing Mobile phase in ion-moderated chromatography References Chapter-14---Chiral-HPLC-separation_2022_Essentials-in-Modern-HPLC-Separatio 14. Chiral HPLC separations 14.1 Separation process in chiral liquid chromatography General comments Chiral recognition Other mechanisms for chiral separations 14.2 Stationary phases and columns for chiral separations Types of chiral phases Brush or “Pirkle” chiral phases Cellulose chiral phases Amylose chiral phases Cyclodextrins and cyclofructans chiral phases Crown ether chiral phases Macrocyclic antibiotics and glycopeptides Protein chiral phases Ligand exchange chiral phases Chiral synthetic polymers 14.3 Characterization of chiral stationary phases General comments Retention behavior of enantiomers on chiral stationary phases 14.4 Selection of a chiral stationary phase General comments The role of column selection in the development of a method for chiral separations 14.5 Mobile phase in chiral HPLC Mobile phase for chiral phases Mobile phase for chiral separations on achiral stationary phase Ion pairing mechanism for enantioseparation References Chapter-15---Size-exclusion-HPLC_2022_Essentials-in-Modern-HPLC-Separations 15. Size exclusion HPLC 15.1 Separation process in size exclusion chromatography General comments 15.2 Stationary phases and columns for size exclusion HPLC General comments Silica-based SEC stationary phases and glass phases Polymer-based phases used in SEC New developments 15.3 Characterization of size exclusion phases and columns General comments Porosity and particle size Inertness and recovery 15.4 Selection of a stationary phase in size exclusion HPLC Selection factors for SEC columns 15.5 Mobile phase for size exclusion separations General comments Typical solvents for gel filtration Typical solvents for gel permeation 15.6 Interaction polymer chromatography General comments Gradient temperature in IPC References Chapter-16---Affinity--immunoaffinity--and-a_2022_Essentials-in-Modern-HPLC- 16. Affinity, immunoaffinity, and aptamer type HPLC 16.1 Separation process in immunoaffinity HPLC General comments 16.2 Types of phases and their preparation in affinity and immunoaffinity chromatography General comments Supports for stationary phases in immunoaffinity chromatography The active phase in immunoaffinity chromatography Other types of affinity chromatography 16.3 Biomimetic liquid chromatography General comments Stationary phases used for biomimetic LC Retention in immobilized artificial membrane LC References Chapter-17---Mixed-mode-HPLC_2022_Essentials-in-Modern-HPLC-Separations 17. Mixed-mode HPLC 17.1 Stationary phases with more than one type of active groups General comments Stationary phases with mixed mode including RP and HILIC capability Stationary phases with mixed mode including ion exchange capability 17.2 Mobile phase in mixed-mode HPLC General comments References Chapter-18---Utilization-of-HPLC-in-chemic_2022_Essentials-in-Modern-HPLC-Se 18. Utilization of HPLC in chemical analysis 18.1 Steps in development and implementation of an HPLC separation General comments Information for starting the development of an HPLC method Selections to be made for an HPLC analysis Comments on the implementation of a method from the literature Improvement of a method from the literature Development of a new HPLC method Method optimization Method validation 18.2 Application of HPLC for quantitative analysis General comments Calibration procedures Selection of the internal standards in HPLC References Appendix-to-Chapter-6_2022_Essentials-in-Modern-HPLC-Separations Appendix to Chapter 6 Appendix-to-chapter-7_2022_Essentials-in-Modern-HPLC-Separations Appendix to chapter 7 Appendix-to-chapter-8_2022_Essentials-in-Modern-HPLC-Separations Appendix to chapter 8 Appendix-to-chapter-9_2022_Essentials-in-Modern-HPLC-Separations Appendix to chapter 9 Appendix-to-chapter-11_2022_Essentials-in-Modern-HPLC-Separations Appendix to chapter 11 Appendix-to-chapter-13_2022_Essentials-in-Modern-HPLC-Separations Appendix to chapter 13 Appendix-to-chapter-14_2022_Essentials-in-Modern-HPLC-Separations Appendix to chapter 14 Appendix-to-chapter-15_2022_Essentials-in-Modern-HPLC-Separations Appendix to chapter 15 Index_2022_Essentials-in-Modern-HPLC-Separations Index A B C D E F G H I K L M N O P Q R S T U V W X Y Z