Contents. List of Contributors XIII The structure of The HPLC-Expert" Preface XVII

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1 V List of Contributors XIII The structure of The HPLC-Expert" Preface XVII XV 1 LC/MS Coupling State of the Art in LC/MS 1 Oliver Schmitz Introduction Ionization Methods at Atmospheric Pressure Overview about API Methods ESI APCI APPI APLI Determination of Ion Suppression Best Ionization for Each Question Mass Analyzer Future Developments What Should You Look for When Buying a Mass Spectrometer? Technical Aspects and Pitfalls of LC/MS Hyphenation 12 Markus M. Martin Instrumental Considerations Does Your Mass Spectrometer Fit Your Purpose? (U)HPLC and Mass Spectrometry When LC Methods and MS Conditions Meet Each Other Flow Rate and Principle of Ion Formation Mobile Phase Composition Quality of Your Mass Spectra and LC/MS Chromatograms No Signal at All Inappropriate Ion Source Settings and their Impact on the Chromatogram Ion Suppression Unknown Mass Signals in the Mass Spectrum 44

2 VI Instrumental Reasons for the Misinterpretation of Mass Spectra Conclusion Abbreviations LC Coupled to MS A User Report 53 Alban Muller and Andreas Hofmann Conditions of the Ion Chromatography Gradient Generator Transitions 56 References 58 2 Optimization Strategies in RP-HPLC 61 Frank Steiner, Stefan Lamotte, and Stavros Kromidas 2.1 Introduction Speed of Analysis Peak Resolution Limit of Detection and Limit of Quantification Costs of Analysis LC Fundamentals Peak Resolution Optimization of Efficiency (The Kinetic Approach) The Term Describing the Eddy Dispersion (A-Term) The Term Describing the Longitudinal Diffusion of Analyte Molecules (B-Term) The Term Describing the Hindrance of Analyte Mass Transfer (C-Term) The Influence of the Column Dimension Methodology of Optimization How to Optimize Selectivity The Role of Selectivity in Practical Method Optimization How to Control Selectivity in HPLC? The Role of Temperature in HPLC Retention and Selectivity Control via Temperature: Possibilities and Limitations Separation Acceleration through Temperature Increase The Value of Mobile Phase Composition versus Temperature in the Strive for Optimization in HPLC Accelerating Separations through Efficiency Improvement of Stationary Phases Systematic Speed-Up by Optimization of Particle Diameter and Column Length Monoliths and Solid Core versus Fully Porous Phase Materials Optimizing Resolution by Particle Size and/or Column Length High-Resolution 1D-LC and 2D-LC to Fully Exploit the Potential 120

3 VII The 2D-LC Approach to Increase Peak Capacities Beyond These Limits Boosting Peak Capacity in 1D-LC Further and How This Translates into Analytical Value Optimization of Limits of Detection and Quantification Absolute Detection Limit (Related to Analyte Mass on Column) Concentration Detection Limit Practical Guide for Optimization General Optimization Workflow and Important Considerations and Precautions Overview on Valuable Rules and Formula Outlook 137 References The Gradient in RP-Chromatography Aspects of Gradient Optimization 151 Stavros Kromidas, Frank Steiner, and Stefan Lamotte Introduction Special Features of the Gradient Some Chromatographic Definitions and Formulas Detection Limit, Peak Capacity, Resolution: Possibilities for Gradient Optimization Detection Limit Peak Capacity and Resolution Gradient Myths" Examples for the Optimization of Gradient Runs: Sufficient Resolution in an Adequate Time About Irregular Components Preliminary Remarks, General Conditions Gradient Aphorisms Prediction of Gradients 177 Hans-Joachim Kuss Linear Model: Prediction from Two Chromatograms What Does the Retention Factor k Tell Us? What Do the Two Retention Factors k g and k e Mean? How Does the Integration- and Control System See the Gradient? How Does the HPLC-Column See the Gradient? How Do the Substances to Be Analyzed See the Gradient? Interpretation of the ln(k)to%b Graph The Instrumental Gradient Delay (Dwell Time) Extension of the Gradient Downwards by Constant Slope Curvilinear Model: More than Two Input Chromatograms The ln(k)-straight Lines Are Often not Straight at All 189

4 VIII The ln(k)to%b Fit According to Neue Predictions with Excel The Interaction Is Temperature Dependant Optimization Parameters Commercial Optimization Programs How Accurate Must the Prediction of k g and k e Be? How to Act Systematically? List of Abbreviations 199 References Comparison and Selection of Modern HPLC Columns 203 Stefan Lamotte, Stavros Kromidas, and Frank Steiner 4.1 Supports Why Silica Gel? Stationary Phases for the HPLC: The Historical Development ph Stability and Restrictions in the Use of Silica The Key Properties of Reversed Phases The Hydrophobicity of Reversed Phases The Hydrophobic Selectivity The Silanophilic Activity Shape Selectivity (Molecular Shape Recognition) Why Is This So? The Polar Selectivity The Metal Content Characterization and Classification of Reversed Phases The Significance of Retention and Selectivity Factors in Column Tests Preliminary Remark Criteria for the Comparison of Columns Column Comparison, Comparison Criteria: Similarity of Selectivities Two Simple Tests for the Characterization of RP Phases Test Test Procedure for Practical Method Development The Interaction between Mobile and Stationary Phase Why Is This? Which Columns Should Be Used, and How Do I Use Them? What to Do, When the Analytes Are Very Polar and Are not Retained on the above-mentioned Columns? AQ Columns, Polar RP Columns, and Ion-Pair Chromatography Mixed-Mode Columns Ion-Exchange Columns/Ligand-Exchange Chromatography HILIC (Hydrophilic Interaction Liquid Chromatography) 232

5 IX Porous Carbon Column Screening Column Databases 239 References Introduction to Biochromatography 243 Jürgen Maier-Rosenkranz 5.1 Introduction Overview of the Stationary Phases Base Materials Characterization of Stationary Phases Particle Form Particle Size Pore Size and Surface Loading Density Purity Functional Group Reversed-Phase Chromatography of Peptides and Proteins Retention Behavior of Peptides and Proteins Gradient Design Organic Modifier Ion Pair Reagent Influence of the ph Value Pore Size Bonding Chemistry IEC Chromatography of Peptides and Proteins IEC Parameters Ionic Strength of the Sample Buffer Concentration of the Eluent ph Value Organic Modifier Temperature Flow Rate Pore Size Loading and Injection Volume Size-Exclusion Chromatography of Peptides and Proteins SEC Parameters Particle Size Pore Size Distribution Pore Volume Flow Rate Temperature Viscosity Loading and Injection Volume Further Types of Chromatography Brief Descriptions 264

6 X Hydrophobic Interaction Chromatography Hydrophilic Interaction Chromatography Affinity Chromatography (AC) Summary Comparison of Modern Chromatographic Data Systems 267 Arno Simon 6.1 Introduction The Forerunners for CDS CDS Today Advantages and Disadvantages of File-Based CDS Advantages and Disadvantages of Database-Supported CDS CDS in a Network Environment Instrument Control Documentation and Compliance Brief Overview of Current Systems Atlas ChemStation Agilent OpenLAB CDS Chromeleon Empower EZchrom Tabular Comparison of Empower and Chromeleon The CDS of Tomorrow MS Integration Large Installation Easy and Intuitive Usability Special Extensions Support of Peak Integration Column Administration Instrument Usage Connection of Balances Open Interfaces Instrument Integration The CDS in 20 Years 283 Acknowledgment Possibilities of Integration Today 285 Mike Hillebrand 7.1 Peak Overlay - Effect on the Chromatogram Separation Techniques for Higher-Level Peaks Lot Method Error by the Vertical Skim Overlapping Peaks (Area Rules to V.R. Meyer) 287

7 XI Tangential and Valley-to-Valley Separation Method Gaussian and Exponential Separation Method Application of Separation Methods Chromatogrammsimulation Deconvolution Evaluation of Separation Methods Practical Application of Deconvolution 294 References Smart Documentation Strategies 301 Stefan Schmitz 8.1 Introduction Objectives of Documentation Documentation from the Organizational Point of View Documentation from the Process Point of View Documentation from the Communication Point of View Documentation from the Information Point of View Documentation from the Knowledge Storage Point of View Regulatory Requirements for Laboratory Documentation The Life Cycle Model for Regulated Documents in Practice Dealing with Hybrid Systems Comprising Paper and Electronic Records Advantages and Disadvantages of Paper Versus Electronic Documents Implementation Strategy Preview 320 References Tips for a Successful FDA Inspection 323 Stefan Schmitz and Iris Retzko 9.1 Introduction Preparation with the Inspection Model Materials, Reagents, and Reference Standards Facilities and Equipment Laboratory Controls Personnel Quality Management Documents and Records Typical Course of an FDA Inspection During the Inspection Behavior in Inspections Lab Walkthrough The Inspection in the Audit Room (Front Office) Dealing with Obviously Serious Observations Documentation of Observations on Form FDA

8 XII 9.5 Post-Processing of the Inspection 341 Further Readings HPLC Link List 343 Torsten Beyer 10.1 Chemical Data Applications/Methods Authorities and Institutions Manufacturers of Analytical Instruments and Columns Journals and Web Portals Troubleshooting Background Information and Theory Literature Publishing Companies for Journals, Books, and Databases Scientific Journals (Full Access with Costs) OpenAccess Journals Free Commercial Journals and Web Pages with Focus on Chromatography Literature Search Engines Databases with Costs STN Databases Data on Chemical Media Literature Apps Social Media Twitter Pages (Examples) Facebook Pages (Examples) 351 Index 353