Principles and Practice of Modern Chromatographics Methods

Description

Front Matter Preface Preface to first edition Introduction and overview Introduction Coverage Chromatographic separation simply explained Classification of chromatography Mobile phase Reversed-phase and normal-phase chromatography Development mode Technique Planar and column chromatography Column types Separation mechanism Adsorption chromatography Partition chromatography Bonded phase chromatography Hydrophilic interaction liquid chromatography (HILIC) Ion-exchange chromatography Ion-interaction chromatography Size-exclusion chromatography Affinity chromatography Micellar or Pseudophase liquid chromatography Complexation chromatography Ion-exclusion chromatography Chiral chromatography Other systems of classification Chromatography: Publications and equipment sales Applications of chromatography Qualitative applications Quantitative applications Chromatographic metabolomics Preparative applications Comparison of chromatographic techniques Analyte characteristics Characteristics of the sample matrix Purpose of the analysis Historical aspects Historical developments in the theory of chromatography Concluding remarks Obtaining assistance References Theoretical considerations Introduction Theory of chromatography Why bother with theory? Model or theory, which is it? Taxonomy of models Equilibrium models Kinetic models Macroscopic kinetic models Microscopic kinetic models Retention, dispersion, and distortion Measures of peak asymmetry Distribution isotherms Retention: Thermodynamics and molecular interactions Retention Prediction of retention Stationary phase selection Method development Measures of chromatographic retention Planar techniques Column techniques Retention factor, k Retention time Compressible mobile phases Retention volume Net and specific retention volume Dispersion Plate theory Plate height Rate theory Factors contributing to dispersion or zone broadening: Van Deemter equation The A term: Eddy diffusion The B term: Molecular or longitudinal diffusion The C term: Resistance to mass transfer Van Deemter plot Is it resolution or separation? Measures of separation and resolution Separation factor Resolution Peak capacity and Trennzahl Summary Optimizing resolution Column length Retention factor General elution problem Column efficiency Column selectivity Summary Extra-column dispersion Worked example Summary: Retention and dispersion Column testing References Planar chromatography Introduction Paper chromatography Mobile phases for paper chromatography Thin layer chromatography Why thin layer chromatography? Comparison of conventional TLC and HPTLC Comparison of TLC with other techniques Theoretical considerations Sample application in TLC Plate development in TLC Development chambers Development techniques Linear development Vertical and horizontal development (one-dimensional single development) One-dimensional multiple and continuous development Two-dimensional development Rotational development Circular and anti-circular development Forced flow development Innovation in TLC Forced flow conditions Ultrathin layer chromatography Hyphenated techniques Thin layer plates Stationary phases Polar inorganic adsorbents Silica gel Alumina Others Activity Pre-loading Standardization of activity Activity order of different adsorbents Layer pre-treatment Non-polar inorganic adsorbents Modified adsorbents Non-polar bonded phases Polar bonded phases Other phases Mobile phases Mobile phase optimization Normal-phase systems Reversed-phase systems Detection: Qualitative analysis Direct examination Spray reagents Spectrometry Mass spectrometry Analyte sampling and ionization Miscellaneous Quantitative analysis In situ visual evaluation Elution techniques Densitometry Slit scanning densitometers Transmittance mode Reflectance mode Combined transmittance-reflectance mode Decrease of phosphorescence Fluorescence mode Instrumentation Diode-array densitometers Image analysers Separations References Gas chromatography Introduction Samples analysed by GC Organization of this chapter Mobile phases and delivery systems Safety considerations Carrier gas delivery systems Carrier gas purification Choosing a mobile phase Carrier gas flow Regulation of carrier gas flow and pressure control Measurement of carrier gas flow Practical considerations Sample introduction in GC Septa Microsyringes Manual syringe handling techniques Packed columns Open tubular columns Auto injection Sample inlet systems Packed column Open tubular column Split injection Splitless injection Cool on-column injection Programmed temperature vaporizer Summary Large volume injection Pyrolysis gas chromatography Headspace gas chromatography Column packings and hardware Columns Packed columns Open tubular columns Column diameter Column length Stationary phase film thickness Column diameter and film thickness Column packings Gas solid chromatography Stationary phases Inorganic oxides Carbon adsorbents Molecular sieves Porous polymers Gas liquid chromatography Solid supports Stationary phases Representative stationary phases Selection of a stationary phase Classification of stationary phases Summary Column installation Measuring system performance Column bleed Solvent and unretained solute test Column efficiency System activity Ratio testing Column care and use Detectors Make-up gas Thermal conductivity detector Flame ionization detector Electron capture detector Thermionic ionization detector Flame photometric detector Other detectors Dual detection Column temperature and temperature programming Temperature programming Derivatization Silylation Acylation Alkylation Oxime formation Innovation Multi-column gas chromatography High-speed gas chromatography High temperature gas chromatography Micro gas chromatography Separations Gas solid chromatography Mechanism of gas solid chromatography Applications Gas liquid chromatography Mechanism of gas liquid chromatography Applications References High performance liquid chromatography: Instrumentation and techniques Introduction From HPLC to UHPLC and beyond Solvent delivery systems General requirements Materials of construction Mobile phase reservoirs Reciprocating HPLC pumps Multisolvent pumps Other types of HPLC pump Sample introduction in HPLC Manual injection Autosamplers Autosampler vials and microplates Column packings and hardware Columns Column packings Packed columns Monolithic and other columns Column packing and preparation methods Column configuration and hardware Column dimensions Measuring column performance Column care and use Detectors Introduction UV-visible absorbance detectors Fluorescence detectors Electrochemical detectors Refractive index detectors Conductivity detectors Aerosol-based detectors Other detectors Detector requirements for UHPLC Post-column derivatization Gradient elution Introduction Gradient elution theory and optimization Dwell volume and gradient elution Gradient applications and considerations Multidimensional liquid chromatography References High performance liquid chromatography: Separations Introduction Chromatographic separations Organization of this chapter Separation of neutral compounds Normal-phase chromatography Introduction Mechanism of normal-phase chromatography Stationary phases for normal-phase chromatography Mobile phases for normal-phase chromatography Solvent strength Solvent selectivity Effect of water Applications of normal-phase chromatography Reversed-phase liquid chromatography Introduction Mechanism of reversed-phase chromatography Stationary phases for reversed-phase liquid chromatography Bonded phase silica columns Silica and silica functionalization Ligands used for bonded phase silica columns Characteristics of bonded phase silica columns Hybrid reversed-phase columns Choosing a reversed-phase column Mobile phases for reversed-phase liquid chromatography Solvent classification Solvent strength Solvent selectivity Other factors Applications of reversed-phase liquid chromatography Hydrophilic interaction liquid chromatography Introduction Mechanism of hydrophilic interaction liquid chromatography Stationary phases for hydrophilic interaction liquid chromatography Mobile phases for hydrophilic interaction liquid chromatography Applications of hydrophilic interaction liquid chromatography Size exclusion chromatography Introduction Mechanism of size exclusion chromatography Stationary phases for size exclusion chromatography Mobile phases for size exclusion chromatography Applications of size exclusion chromatography Techniques for ionic and ionizable species Ion-suppression chromatography Ion-interaction chromatography Introduction Stationary and mobile phases for ion-interaction chromatography Mechanism of ion-interaction chromatography Factors affecting retention in ion-interaction chromatography Applications of ion-interaction chromatography Ion-exchange chromatography Introduction Mechanism of ion-exchange chromatography Stationary and mobile phases for ion-exchange chromatography Factors affecting retention in ion-exchange chromatography Applications of ion-exchange chromatography Ion chromatography Introduction Stationary and mobile phases for ion chromatography Mechanism of ion chromatography Applications of ion chromatography Ion-exclusion chromatography Introduction Mechanism of ion-exclusion chromatography Stationary and mobile phases for ion-exclusion chromatography Factors affecting retention in ion-exclusion chromatography Applications of ion-exclusion chromatography Specialty separation modes Hydrophobic interaction chromatography Affinity chromatography Complexation chromatography Chiral chromatography Choosing a chromatographic method References Supercritical fluid chromatography Introduction History Instrumentation Factors affecting retention Mobile phases and delivery systems Safety considerations Hardware Back pressure regulators Mobile phases Alternatives to carbon dioxide Modifiers Mobile phase flow Temperature/Pressure effects Sample introduction in SFC Column packings and hardware Open tubular columns Packed column SFC Detectors Programming techniques Separations References Coupled systems Introduction Multidimensional chromatography LC-GC and LCxGC Hyphenated techniques Mass spectrometry Infrared spectrometry Nuclear magnetic resonance spectrometry GC-based Gas chromatography-mass spectrometry Ionization methods Mass analyser Scanning mode Data Gas chromatography-Fourier transform infrared spectrometry GC-MS or GC-FTIR? Other hyphenated techniques involving GC LC based Liquid chromatography-mass spectrometry Ionization methods Mass analyser Enhancing specificity UHPLC Liquid chromatography-nuclear magnetic resonance spectrometry Liquid chromatography-fourier transform infrared spectrometry SFC-based References Analyses Introduction Detectors for chromatography Specifications Sensitivity Linear response Dynamic range Minimum detectable quantity Time constant and response time Selectivity of response Other factors Noise Classification Data handling Peak area versus peak height measurement Manual approaches Computerized approaches Data acquisition Data processing Peak shape Peak finding Integration Mathematical peak deconvolution Chromatography data management system report Chromatographic efficiency Qualitative analysis Retention parameters Relative retention Retention indices Gas chromatography High-performance liquid and supercritical fluid chromatography Retention and molecular structure Chemical methods Peak trapping and off-line spectrometric methods Selective detectors Coupled techniques Quantitative analysis Calibration procedures Normalization External calibration Internal standard Standard addition Worked examples Case 1. The gas chromatographic determination of xylenes in a commercial mixture Case 2. The characterization of a vegetable oil by gas chromatographic determination of fatty acid content. Case 3. Determination of nicotinic acid in instant coffee Case 4. Determination of bromate in bread dough Case 5. The determination of polychlorinated biphenyls in environmental samples Case 6. The determination of ethanol in a blood sample Case 7. The determination of cocaine Case 8. The determination of caffeine and theobromine in chocolate products What can be done if no analyte is detected? Metabolomics and chromatography Measurement of analytical signal Separation Gas chromatography Liquid chromatography Supercritical fluid chromatography Two-dimensional chromatography Detection Data handling Peak detection Peak alignment Normalization Compound annotation Chemometrics Applications References Sample handling in chromatography Introduction Why bother with sample handling? Sample collection procedures Sustainable green chemistry Sample preparation Solvent extraction Efficiency in liquid-liquid extraction Selection of extracting solvent Extraction modes Batch extraction Continuous extraction Countercurrent extraction Extraction of solid samples Supercritical fluid extraction Instrumentation Selecting a supercritical fluid and extraction conditions Microwave- and sonication-assisted solvent extraction Accelerated solvent extraction Membrane-assisted techniques Filtration Microfiltration Ultrafiltration (and nanofiltration) Reverse osmosis Dialysis Volatilization processes Sublimation Freeze drying Distillation Fractional distillation Steam distillation Assisted co-distillation Chromatography Columns Separation mechanisms Adsorption Column packings Mobile phase Ion Exchange Size Exclusion Solid-phase extraction Modes of operation Applications Microextraction techniques Pre-concentration techniques References Preparative chromatography Introduction History Theoretical considerations Thin layer chromatography Plates for PTLC Sample application Mobile phases Layer development Visualization Applications Gas chromatography Instrumentation Applications Supercritical fluid chromatography Instrumentation Applications High-performance liquid chromatography Instrumentation Separations Applications References Index A B C D E F G H I K L M N O P Q R S T U V W Z