Gerhard Schomburg. Gas Chromatography. A Practical Course. -«WTM-JY// ^ Weinheim New York. VCH XJ Basel Cambridge

Transcription

1 Gerhard Schomburg Gas Chromatography A Practical Course -«WTM-JY// ^ Weinheim New York VCH XJ Basel Cambridge

2 Contents 1 The Role of Gas Chromatography Among Other Methods of Instrumental Analysis 1 2 Design and Functions of Instrumentation for Gas Chromatography 5 3 The Basic Theory of Chromatographic Separations 9 4 The Gas Chromatogram The Time Coordinate of the Gas Chromatogram Retention Time or Volume Relationships between Retention Time, Capacity Ratio and Partition Coefficient Peak Width, Theoretical Plate Number, Separation Efficiency Resolution Relationships between Resolution, Efficiency and Capacity Ratio The Intensity Coordinate of the Gaschromatogram 26 References for Sections Journals and Periodicals in which Publications on Gas Chromatography Topics may Appear 29 5 Elements and Parameters of Gas Chromatographic > irf -"&. Instrumentation GC Instruments and their Optimization Separation Columns Packed Columns Capillary Columns Connection Techniques for Capillary Columns Couplings of Capillary Columns Optimization of Column Parameters Column Temperature Carrier Gas Flow Column Ovens Sample Introduction Techniques Sample Volume Split Injection: Sample Introduction with External Vaporization with Splitting of the Carrier Gas Flow 53

3 VIII Contents Splitless Injection of Dilute Samples: Sample Introduction with External Vaporization without Splitting On-Column Sample Introduction Temperature-Programmed Vaporization: Cold Sample Introduction and Temperature-Programmed External Vaporization Introduction of Gaseous Samples Head Space Sample Introduction Gas Chromatographic Detectors Detectors with Concentration-Dependent Signal Intensity Detectors with Mass Flow-Dependent Signal Intensity General Properties and Parameters of GC Detectors GC Instruments for Practical Analyses: Systems and Functions Packed Columns in Combination with TCD and/or FID, Split and Splitless Sampling Combinations of Capillary Columns with FID, N, P-FID, ECD, Multichannel Detection and Various Sampling Devices such as Split, Splitless and On-Column Coupling of GC Systems to Mass or FTIR Spectrometers GC-MS Combination GC-FTIR Combination 80 References 82 6 Methods of Qualitative and Quantitative GC Analysis of Mixtures Qualitative Analysis Sample Types, Sample Pretreatment, Chromatographic Volatility of Components Considerations before the Execution of a GC Separation Standard GC Instrumentation for Use with Capillary Columns Test Measurements and Optimization of the GC System before the Actual Analysis Qualitative GC Analysis of Samples of Unknown Composition Identification of the Separated Species Identification from Absolute and Relative Retention Data The Retention Index System The Kovats Retention Index Types of Intermolecular Interaction between Solute and Stationary Phase Retention and Chemical Structure of Solutes Comparison of Retention Indices of Two Compounds of Different Structure Obtained with the same Stationary Phase Comparison of Retention Indices of a Single Compound Measured with Two Stationary Phases of Different Polarity Temperature Dependence of Retention Indices, Quantitative GC Analysis Criteria of Good Quantitative Analyses for the Analytical Practice Quantitative Evaluation of Chromatograms via Peak Heights or Areas. 109

4 Contents IX Determination, Application and Prediction of Response Factors for Use in Quantitative Analysis via Peak Areas Ill Response Correction Factors for the TCD and the FID Determination of Response Factors Response Factors for TCD and FID, Influence of Chemical Structure Incremental Prediction of FID Response Factors Evaluation of the Concentrations of Components in the Sample from Peak Areas Absolute Calibration: Peak Areas versus Sample Volume The Internal Normalization Method of Chromatogram Evaluation via Peak Areas The Internal Standard Method of Chromatogram Evaluation via Peak Areas /. 120 References Special Methods, Auxiliary Techniques and Applications of Gas Chromatography Analysis of Samples of Complex Mixtures Separation of Volatile and/or Non-polar Samples. Gas Analysis by Gas Chromatography Separation of Compounds of Low Volatility; High Temperature GC Separation of Highly Polar Compounds; Derivatization Separation and Detection of Trace Components by Specific Detection Determination of Trace components of Known Chemical Structure; Trace Analysis for Target Compounds Specific Detection of Trace Components Automation of GC Analyses; Process Control GC Automated Execution of Sample Introduction, Separation and Detection Handling of GC Data by Computers Coupled GC Systems, Multi-dimensional GC Separations Analytical Objectives of Multi-Dimensional Separations Coupling of Two Capillary Columns with Different Stationary Phase Contents Coupling of Two Capillary Columns with Stationary Phases of Different Polarities Coupling of Two Capillary Columns in a Double Oven Instrument Using an ECD as Monitor Detector and Parallel Detection with FID and ECD for the Second (Main) Separation. Multi-dimensional GC of Chlorinated Aromatic Hydrocarbons Coupling of a Packed to Capillary Column Coupling of Chemical Reactors to GC Columns. Reaction Gas Chromatography Pre-column Reaction Gas Chromatography: On line Hydrogenation, PyrolysisGC 146

5 X Contents On-line Hydrogenation of Unsaturated Species Pyrolysis Gas Chromatography Post-Column Reaction Gas Chromatography Trace Analysis for CO and CO 2 by Post-column Hydrogenation On-Line Hydrogenation of Unsaturated Species After Elution from the Separation Column and Before Entering the Ion Source of the Mass Spectrometer Specific Detection of Oxygenated Hydrocarbons 151 References Sources of Analytical Error in Gas Chromatographic Systems: Elucidation and Elimination Recognition of Instrumental Errors in the Chromatographic System from the Analog Chromatogram Distortion of Peak Shapes Thermodynamic Reasons for Bad Peak Symmetry Overloading of a Non-polar Methylpolysiloxane Capillary Column by the Highly Polar Free Fatty Acids Instrumental Sources of Bad Peak Symmetry Influence of Flow Geometry Influence of Inadequate Execution of Sample Introduction Unsymmetrical and Overlapped Peak Shapes Originating from Thermal or Catalytic Conversion of Labile Sample Components Appearance of Too Broad Peaks in the Chromatogram The Peaks in Isothermal Chromatograms are Broad with Generally Bad Resolution Individual Peaks in the Isothermal Gas Chromatogram are Broader than the Neighbouring Peaks with Longer Retentions Appearance of Too Narrow Peak Profiles in the Entire Chromatogram Causes of More Complicated Peak Shapes Disturbances to the Baseline of the Chromatogram Elimination of Sources of Deteriorated Chromatogram Performance Sources of Error in Retention Data Measurements Elimination of Negative Effects on Retention Data Measurements Sources of Error in Quantitative GC Analysis Problems with the Evaluation of the Correct Baseline for Quantitation of Insufficiently Resolved Chromatograms of Complex Preferably Isomeric Mixtures 170 References Analytical Supercritical Fluid Chromatography Principles and Methods for SFC Instrumentation for SFC Columns and Column Ovens Pumping Systems for Mobile Phase Delivery 178

6 Contents XI Sample Introduction Devices Restrictors Detectors Typical Applications of SFC 181 References The Coupling of LC and GC Pretreatment of Complex Samples by Liquid Chromatography with Direct Transfer of Eluate Cuts into Capillary GC Systems 189 References Gas Chromatographic Applications Using Different Methods and Techniques Characteristics and Criteria of Good GC Separations with Regard to Qualitative and Quantitative Objectives of Analysis Isothermal Separation of a Series of Homologous n-alkanes Temperature-Programmed Separation of a Series of. Homologous n-alkanes Temperature Programmed Separation of Complex Hydrocarbon Mixtures Temperature-Programmed Separation of a C 10 -C 25 Petroleum Fraction Temperature-Programmed Separation of a Petroleum Fraction Using a Narrow-Bore Capillary Column Separation of the Phytane Diastereomers (C 20 tetraisoprenoid) by Optimization of Efficiency, Temperature and Polarity Using a PEG (CW 20M) Column Saturated and Unsaturated Volatile CJ-CJ Hydrocarbons C r C 5 Hydrocarbons Separated with a Column Packed with a Porous Polydivinyl Polymer CJ-CJ Hydrocarbons Separated with GLC Capillary Columns with a Thick Film Stationary Phase Coating GSC Capillary Columns Coated with Alumina Test Sample of Components Applied as Propellents for Spray Cans Low Molecular Weight Halogenated Hydrocarbons with Electron Capture Detection, ECD Halocarbon Compounds Contained in Tap Water Using an Apolar Thick-Film Capillary Column and Electron Capture Detection Polychlorinated Biphenyls (PCB's) Using a Narrow Bore Capillary Column and Electron Capture Detection Highly Polar Compounds Using a Polar PEG Capillary Column and Thermal Conductivity Detection Aqueous Solution of Apple Flavor Compounds Using a PEG Capillary Column with Thermal Conductivity and Flame Ionization Detection 218

7 XII Contents Determination of Aromatic Hydrocarbons and Oxygenates such as Methanol, tert.-butanol and Isobutanol in Gasoline Multi-dimensional Separation of Aromatic Hydrocarbons and Oxygenates such as Aliphatic Alcohols and Methyl tert.-butyl Ether Solvent Mixture Containing Hydrocarbons, Ethylene Glycol and Isomeric Phenols Separated Using a Polyethylene Glycol Column Test Mixtures for the Characterization of the Surface Adsorptivity of Capillary Columns Grob-Test for Efficiency, Polarity and Adsorptivity of a Non-polar Methylpolysiloxane OV-1 Column Grob-Test of a Methylpolysiloxane OV-1 Column with Incompletely Dealkalized Support Surface Grob-Test of a Polar Polyethylene Glycol (CW 20 M) Column Hindelang Round-Robin Capillary Column Test Mixture High-Speed Separation of Alkylbenzenes with a Capillary Column of Small Inner Diameter Polyaromatic Hydrocarbons from Coal Tar, Separation with a Thin Film Methylpolysiloxane OV-1 Column Polyaromatic and Heterocyclic Hydrocarbons, Simultaneous Detection with FID and NFID Saturated and Unsaturated Hydrocarbons Originating from Date Fruits, Separated with and without On-line Hydrogenation Saturated and Unsaturated Fatty Acid Methyl Esters Obtained from the Triglycerides of Fish Oil Triglycerides of Fish Oil Separated with a Non-selective Methylpolysiloxane Column Fatty Acid Methyl Esters (FAME) Obtained from Fish Oil by Transesterification Separated with an Apiezon M Glass Capillary Column with and without On-line Hydrogenation Unsaturated C 18 -FAMEs Obtained from Lipids of Pimpinella anisium Cell Cultures and from Triglyerides of Fish- and Sunflower Oil Compared with FAMEs in a Test Mixture, Separated with a 120 msilarlocp Glass Capillary Column Triglyerides of Palm Oil Separated with a Methylpolysiloxane (OV-1) and a Polar Methylphenylpolysiloxane (OV-17) Column With a Non-Polar OV-1 Column, the Elution Sequence of the Different Triglycerides Depends on: With the Polar, Phenyl-Substituted OV-17 Methylpolysiloxane Column, the Elution Sequence is Different and Depends on: Test Mixture of Morphine Drugs Trace Concentration of Polychlorinated Biphenyls (PCBs) in Used Mineral Oils by Simultaneous Detection with FID and ECD

8 Contents XIII Analysis of Kirsch Test Mixture Containing C 2 -C 5 Diols Phenols, Cresols and Xylenols Chlorophenols with Flame Ionization- and Electron-Capture Detection FID ECD Phenols Derivatized by Silylation, Detection with FID and ECD Polychlorinated Dibenzo-p-dioxins and Dibenzofurans Polychlorinated Dibenzo-p-dioxins and Dibenzofurans, Detected by ECD Tetrachlorinated Dibenzo-p-dioxins Detected by GC-MS-SIM Recorded at m/z Multi-Dimensional GC-analysis for 2, 3, 7, 8-TCDD Aroma Extracts from Beer and Wine Separated with an Apolar Methylpolysiloxane OV-1-Column Acetylated Polyalcohols, Alditols and Some Amino Derivatives Chiral Stationary GC Phases for the Separation of Enantiomers Enantiomer Separation of Underivatized Prominal and Evipan N-Pentafluoropropanoyl Derivatives of the Isopropyl Esters of DL-Amino Acids. Separation of a Test Mixture of 17 DL-Amino Acids and a Total Hydrolysate of the Peptide Antibiotic Herbicolin A Multi-Dimensional Separation of the Isopropylurethanes of the Four Diastereomeric Menthols Trifluoroacetylated a- and p-pyranosidic Hexoses: Galactose, Mannose and Glucose Isopropylurethanes of Eight Enantiomeric Pairs of 2-Aminoalkanes Enantiomeric y-lactones Separated with Hexakis (3-O-butyryl-2, 6- di-o-pentyl) -oc-cyclodextrin Enantiomer Separation of 3-Methyl-1 -hexene, 2-Bromobutane and 3-Methyl-cyclohexene with Perpentyl-p-cyclodextrin Enantiomer Separation of Limonene, Camphene and a-pinene Using Heptakis (3-O-methyl-2,6-di-O-pentyl)-(3-cyclodextrin Important Equations and Terminology of Gas Chromatography Equations Total or Gross Retention Time, t^ Net Retention Time, t s and Dead Time, t m ' Capacity Ratio, k' Capacity Ratio and Partition Coefficient, K, Phase Ratio, ( Absolute Retention Data, Corrected Net Retention Volumes Relative Retention Data Relative Volatility Selectivity Coefficient Retention Index Kovats Retention Index, I of a Single Solute x 293

9 XIV Contents Difference, AI, of Retention Indices of the Same Solute Obtained with Different Stationary Phases Linear Retention Index Theoretical Plate Number N Van Deemter-Golay Equation Resolution of Chromatographic Separations Separation Number (Trennzahl), TZ Glossary of Terms Used in the Theory and Practice of Gas Chromatography List of Symbols and Acronyms Index 313