Static Headspace-Gas Chromatography

Dr. BRUNO KOLB is an internationally recognized expert on gas chromatography. Until his retirement in 1996, he managed the GC Applications Laboratory at Perkin-Elmer Corporation, Germany; he has also been involved in instrument development with special emphasis on specific detectors. He has been a guest lecturer at the University of Konstanz, as well as at international meetings. He has published many journal articles and book chapters, and is the author of a textbook on gas chromatography.Dr. LESLIE S. ETTRE was a senior scientist at Perkin-Elmer Corporation until his retirement in 1990. Between 1988 and 1995 he served as an adjunct professor in the Department of Chemical Engineering at Yale University, and from 1995 until 2004 he continued his association with the school as a research affiliate. In addition to lecturing widely in the field of gas chromatography, Dr. Ettre has published over 200 scientific and technical papers, and is the author and editor of numerous books, including Encyclopedia of Industrial Chemical Analysis. He has received numerous awards, including the National Award in Chromatography of the American Chemical Society and the AJP Martin Award of the Chromatographic Society—the highest honors in the United States and Europe, respectively.

• Preface xiPreface to the First Edition xvList of Acronyms and Symbols xix1 General Introduction 11.1 Principles of Headspace Analysis 11.2 Types of Headspace Analysis 31.2.1 Principles of Static HS-GC 41.2.2 Principles of Dynamic HS-GC 51.2.2.1 The Trap 51.2.2.2 The Water Problem 71.2.2.3 The Flow Problem 71.2.2.4 The Time Problem 81.2.2.5 Comparison of Static HS-GC with P&T 91.3 The Evolution of the HS-GC Methods 101.4 HS-GS Literature 121.5 Regulatory Methods Utilizing (Static) HS-GC 13References 152 Theoretical Background of HS-GC and Its Applications 192.1 Basic Theory of Headspace Analysis 192.2 Basic Physicochemical Relationships 232.3 Headspace Sensitivity 252.3.1 Influence of Temperature on Vapor Pressure and Partition Coefficient 262.3.1.1 Enhancement of Lower Boiling Compounds 282.3.2 Influence of Temperature on Headspace Sensitivity for Compounds with Differing Partition Coefficients 292.3.3 Influence of Sample Volume on Headspace Sensitivity for Compounds with Differing Partition Coefficients 342.3.3.1 Sample-to-Sample Reproducibility 362.3.4 Changing the Sample Matrix by Varying the Activity Coefficient 372.4 Headspace Linearity 422.5 Duplicate Analyses 432.6 Multiple Headspace Extraction (MHE) 452.6.1 Principles of MHE 452.6.2 Theoretical Background of MHE 462.6.3 Simplified MHE Calculation 49References 493 The Technique of HS-GC 513.1 Sample Vials 533.1.1 Vial Types 533.1.2 Selection of the Vial Volume 543.1.3 Vial Cleaning 553.1.4 Wall Adsorption Effects 553.2 Caps 563.2.1 Pressure on Caps 583.2.2 Safety Closures 583.3 Septa 583.3.1 Septa Types 583.3.2 Septum Blank 603.3.3 Should a Septum Be Pierced Twice? 623.3.3.1 Closed-Vial versus Open-Vial Sample Introduction Technique 653.4 Thermostatting 663.4.1 Influence of Temperature 663.4.2 Working Modes 693.5 The Fundamental Principles of Headspace Sampling Systems 703.5.1 Systems Using Gas Syringes 703.5.2 Solid Phase Microextraction (SPME) 733.5.2.1 Comparison of the Sensitivities in HS-SPME and Direct Static HS-GC 803.5.3 Balanced Pressure Sampling Systems 813.5.4 Pressure/Loop Systems 833.5.5 Conditions for Pressurization Systems 843.5.6 Volume of the Headspace Gas Sample 863.5.6.1 Sample Volume with Gas Syringes 873.5.6.2 Sample Volume with Loop Systems 873.5.6.3 Sample Volume with the Balanced Pressure System 883.6 Use of Open-Tubular (Capillary) Columns 893.6.1 Properties of Open-Tubular Columns for Gas Samples 893.6.2 Headspace Sampling with Split or Splitless Introduction 903.6.3 Comparison of Split and Splitless Headspace Sampling 933.6.4 Band Broadening During Sample Introduction 963.6.5 Influence of Temperature on Band Broadening 993.6.5.1 Conclusions 1013.6.6 The Combination of Different Columns and Detectors 1013.7 Enrichment Techniques in HS-GC 1053.7.1 Systems for Cryogenic Trapping 1083.7.1.1 Trapping by Cryogenic Condensation 1093.7.1.2 Trapping by Cryogenic Focusing 1103.7.1.3 Influence of Temperature on Cryogenic Focusing 1183.7.1.4 Comparison of the Various Techniques of Cryogenic Trapping 1223.7.2 Influence of Water in Cryogenic HS-GC 1243.7.2.1 Water Removal in Static HS-GC 1273.7.2.2 Applications 1293.7.3 Enrichment by Adsorption 1343.7.3.1 Water Removal from an Adsorption Trap 1343.8 Special Techniques with the Balanced Pressure Systems 1393.8.1 Instrumentation for MHE 1393.8.2 Backflushing 1403.9 Reaction HS-GC 1433.9.1 Derivatization in the Headspace Vial 1453.9.1.1 Methylation 1463.9.1.2 Esterification 1463.9.1.3 Transesterification 1483.9.1.4 Acetylation 1493.9.1.5 Carbonyl Compounds 1493.9.2 Subtraction HS-GC 1493.9.3 Special Reactions 1533.9.4 HS-GC Analysis of Volatile Derivatives from Inorganic Compounds 158References 1604 Sample Handling in HS-GC 1654.1 Equilibration 1664.1.1 Gas Samples 1674.1.2 Liquid Samples 1684.1.2.1 General Properties 1684.1.2.2 Reduction of the Equilibration Time for Liquid Samples 1694.1.3 Solid Samples 1714.2 Solution Approach 1744.3 Sample Handling and Sample Introduction 1774.3.1 Gas Samples 1774.3.2 Liquid Samples 1794.3.3 Solid Samples 1804.4 Preparation of Standard Solutions 1814.4.1 Preparation of a Standard Solution from a Liquid or Solid Substance 1824.4.2 Preparation of a Standard Solution from a Gaseous Compound 1844.5 Influence of the Matrix 1864.5.1 Clean Matrix is Available 1874.5.2 Matrix Effect Can Be Eliminated 1874.5.3 Artificial Matrix Can Be Prepared 1894.6 Methods Aiming at Complete Evaporation of the Analyte 1894.6.1 The Total Vaporization Technique (TVT) 1904.6.2 The Full Evaporation Technique (FET) 1914.6.3 Calculation of the Extraction Yield in FET 1944.6.4 Comparison of Headspace Sensitivities 195References 1955 Headspace Methods for Quantitative Analysis 1975.1 Internal Normalization 1995.2 Internal Standard Method 2025.2.1 Blood Alcohol Determination 2075.3 External Standard Method 2075.4 Standard Addition Method 2135.4.1 Single Addition 2135.4.2 Handling of the Added Standard 2145.4.3 Determination by Multiple Additions 2185.5 Multiple Headspace Extraction (MHE) 2215.5.1 Principles of MHE 2215.5.2 Calibration in MHE 2225.5.2.1 External Standard 2225.5.2.2 Internal Standard 2265.5.2.3 Standard Addition 2265.5.3 The Use of Gaseous External Standards in MHE 2275.5.3.1 Correction for Sample Volume 2285.5.4 The Role of Quotient Q 2295.5.4.1 Relationship between Q and Pressures 2295.5.4.2 Value of Q in the Case of Total Vaporization 2305.5.4.3 The Relative Position of the MHE Plots as a Function of Q 2325.5.5 The Correlation Coefficient r 2345.5.6 Evaluation of the Shape of the Regression Plot 2345.5.7 Influence of K/ß 2365.6 Analysis of Solid Samples (Adsorption Systems) 2375.6.1 Suspension Approach 2385.6.2 Surface-Modification Techniques 2445.6.3 Highly Adsorptive Solid Samples 2505.7 Calibration Techniques with Headspace Samples of Varying Volumes 2525.8 Analysis of Gas Samples 253References 2556 Method Development in HS-GC 2576.1 General Guidelines 2586.2 Determination of the Residual Monomer Content of Polystyrene Pellets 2596.2.1 First Approach: Use of Internal Standard with MHE 2596.2.2 Second Approach: Single Determination with Internal Standard 2626.2.3 Third Approach: Use of External Standard with MHE 2636.2.4 Fourth Approach: Use of the Solution Approach 2636.3 Determination of Residual Solvents in a Printed Plastic Film 2636.3.1 First Approach: Use of External Standard with MHE 2656.3.2 Second Approach: Use of Standard Addition with MHE 2666.3.3 Third Approach: Use of Internal Standard 2676.3.4 Fourth Approach: Use of Standard Addition 2676.4 Determination of the Volatile Constituents of a Cathodic Electrolytic Plating Bath 2686.4.1 First Approach: Use of External Standard with MHE 2686.4.2 Second Approach: Dilution and Use of External Standard 2697 Nonequilibrium Static Headspace Analysis 2717.1 Accelerated Analysis 2727.2 Heat-Sensitive Samples 274References 2778 Qualitative Analysis by HS-GC 2798.1 The Use of HS-GC in “Fingerprinting” 2828.2 The Use of Headspace Sampling in Hyphenated Systems 2828.3 The Use of HS-GC in Microbiology 286References 2919 Special Measurements 2939.1 Determination of Vapor Pressures 2949.2 Determination of Activity Coefficients 2999.3 Determination of Related Physicochemical Functions 3029.4 Determination of Phase Distribution (Partition Coefficient) 3039.4.1 The Vapor-Phase Calibration (VPC) Method 3059.4.2 The Phase Ratio Variation (PRV) Method 3089.4.2.1 Principles 3099.4.2.2 Limitation of the PRV Method 3119.4.3 MHE Methods for the Determination of the Partition Coefficient 3129.4.3.1 VPC/MHE Method 3139.4.3.2 PRV/MHE Method 3169.5 Reaction Constant Measurements 3169.6 Determination of Solute Solubility by MHE 3199.7 Gas–Solid Systems 3209.7.1 Determination of Adsorption Isotherms 3209.7.2 Determination of the Rate of Release of a Volatile Analyte 3219.8 Validation of Headspace Instrumentation: Investigation of Detector Linearity and Detection Limit 3249.8.1 Definitions 3259.8.2 Linear Range of the Detector 3269.8.3 Precision of the Range 3309.8.4 Minimum Detectability 330References 332Index 335

"This is an important resource on an increasingly useful technique. It should be in the library of any chromatographer...Essential." (CHOICE, November 2006)