The Troubleshooting and Maintenance Guide for Gas Chromatographers

Abstract

Preface. Intentions and Introduction. 1 Introduction to Capillary Gas Chromatography. 1.1 What Is Gas Chromatography? 1.2 What Types of Compounds Are Suitable for GC Analysis? 1.3 The Basic Parts of a Gas Chromatograph. 1.4 The Chromatogram. 1.5 The Mechanism of Compound Separation. 1.6 Factors Affecting Separation. 2 Basic Definitions and Equations. 2.1 Why Bother? 2.2 Peak Shapes. 2.3 Retention. 2.4 Phase Ratio (beta). 2.5 Distribution Constant (KC). 2.6 Column Ef. ciency. 2.7 Utilization of Theoretical Ef. ciency (UTE%). 2.8 Separation Factor (alpha). 2.9 Resolution (R). 2.10 Trennzahl (TZ). 2.11 Column Capacity. 3 Capillary GC Columns: Tubing. 3.1 Fused Silica Capillary Columns. 3.2 Fused Silica Tubing. 3.3 Outer Coating. 3.4 Other Tubing Materials. 3.5 Polyimide Fused Silica Tubing Bending Stress. 4 Capillary GC Columns: Stationary Phases. 4.1 Stationary Phases. 4.2 Types of Stationary Phases. 4.3 Characteristics of Stationary Phases. 4.4 Stationary Phase Interactions. 4.5 Stationary Phase Equivalencies. 4.6 Column Temperature Limits. 4.7 Column Bleed. 4.8 Selecting Stationary Phases. 5 Capillary GC Columns: Dimensions. 5.1 Introduction. 5.2 Column Length. 5.3 Column Diameter. 5.4 Column Film Thickness. 5.5 Manipulating Multiple Column Dimensions. 6 Carrier Gas. 6.1 Carrier Gas and Capillary Columns. 6.2 Linear Velocity versus Flow Rate. 6.3 Controlling the Linear Velocity and Flow Rate. 6.4 Van Deemter Curves. 6.5 Carrier Gas Measurements. 6.6 Carrier Gas Selection. 6.7 Recommended Average Linear Velocities. 6.8 Gas Purities. 6.9 Common Carrier Gas Problems. 7 Injectors. 7.1 Introduction. 7.2 The Basics of Vaporization Injectors. 7.3 Split Injectors. 7.4 Splitless Injectors. 7.5 Direct Injectors. 7.6 Cool On-Column Injectors. 7.7 Pressure and Flow Programmable Injectors. 7.8 Injection Techniques. 7.9 Autosamplers. 7.10 Injector Septa. 7.11 Injector Maintenance. 8 Detectors. 8.1 Introduction. 8.2 Detector Characteristics. 8.3 Flame Ionization Detector (FID). 8.4 Nitrogen-Phosphorus Detector (NPD). 8.5 Electron Capture Detector (ECD). 8.6 Thermal Conductivity Detector (TCD). 8.7 Flame Photometric Detector (FPD). 8.8 Mass Spectrometers (MS). 9 Column Installation. 9.1 Importance of a Properly Installed Column. 9.2 Installing Fused Silica Capillary Columns. 9.3 Column Ferrules. 9.4 Tightening Fittings. 9.5 Techniques for Measuring Column Insertion Distances. 9.6 Leak Detection. 10 Column Test Mixtures. 10.1 Column Performance Testing. 10.2 Column Test Mixture Compounds. 10.3 Column Testing Conditions. 10.4 Grob Test. 10.5 Own Test Mixture. 10.6 When to Test a Column. 11 Causes and Prevention of Column Damage. 11.1 Causes of Column Damage and Performance Degradation. 11.2 Column Breakage. 11.3 Thermal Damage. 11.4 Oxygen Damage. 11.5 Chemical Damage. 11.6 Column Contamination. 11.7 Solvent Rinsing Columns. 11.8 Guard Columns and Retention Gaps. 11.9 Packed Injector Liners. 11.10 Gas Impurity Traps. 11.11 Column Storage. 11.12 Column Repair. 12 Troubleshooting Guidelines, Approaches and Tests. 12.1 Introduction. 12.2 Approaches to Solving GC Problems. 12.3 Troubleshooting Tools. 12.4 Troubleshooting Tests. 13 Common Capillary GC Problems and Probable Causes. 13.1 Using This Troubleshooting Guide. 13.2 Troubleshooting Checklist and Pre-Work. 13.3 Baseline Problems. 13.4 Peak Shape Problems. 13.5 Split Peaks. 13.6 Negative Peaks. 13.7 Excessively Broad Solvent Front. 13.8 Loss of Resolution. 13.9 Retention Changes. 13.10 Peak Size Problems. 13.11 Extra or Ghost Peaks (Carryover). 13.12 Rapid Column Deterioration. 13.13 Quantitation Problems. Appendix A Terms. Appendix B Equations. Appendix C Mass, Volume and Length Unit Conversions. Appendix D Column Bleed Mass Spectra. Appendix E The Basics of High Speed GC Using Small Diameter Columns. E.1 Introduction. E.2 Column Considerations. E.3 Carrier Gas Considerations. E.4 Injector Considerations. E.5 Detector and Data System Considerations. E.6 GC Oven Considerations. E.7 Sample Considerations. E.8 An Example of High Speed GC Using a Small Diameter Column. E.9 High Speed GC Summary. Appendix F Basic Quantitative Capillary GC. F.1 Intentions. F.2 De. nitions. F.3 Concentration. F.4 Density (rho). F.5 Calibration for Quantitative Purposes. F.6 Quantitation Calculations. F.7 Techniques for Preparation of Analytical Standards for GC. References. Subject Index.