123 phase and hence have no direct bearing on the retention time of solutes. However in gas-solid chromatography, a considerable quantity of the mobile phase may be adsorbed on the surface of the stationary adsorbent which diminishes the column's effective length and ability to retain solutes. In this respect helium has been found to be preferable to most other gases (GREENE and Roy, 1957) because it is adsorbed to the least extent. 3. Packed columns offer a considerable resistance to flow, which may create a pressure differential between inlet and outlet of sufficient magnitude to cause an unfavorable flow rate through a significant length of the column. A reduced inlet/outlet pressure ratio can be obtained by using light molecular weight gases toward which the column packing shows the greatest permeability. The flow rate of the mobile phase is normally adjusted by altering the column inlet pressure, for which purpose commercial pressure regulators of sufficient accuracy are available. Quantitative measurements of the flow rate can be made by a number of methods, including rotameters, orifice meters, soapfilm flow meters and displacement of water. The former two methods are the most con­ venient but the least accurate; moreover they create a back pressure and are temperature dependent whereas although the moving soap bubble is cumbersome to employ and unusable for continuous readings, it is preferred when the highest accuracy is required.

- Contents.- Emission and Atomic Absorption Spectrochemical Methods..- A. Flame Emission Methods.- I. Lundegardh Method.- II. Flame Photometric Method for Sodium, Potassium and Calcium.- III. Flame Spectrophotometric Method for Magnesium.- IV. Flame Spectrophotometric Method for Iron, Manganese and Copper.- B. Arc Emission Analysis.- I. The Variable Internal Standard, Cathode Layer Method.- II. Direct Cathode Layer Analysis of Plant Ash.- III. The Method of Successive Additions.- C. Spark Emission Methods.- I. Porous Cup Solution Spark Method for Magnesium.- II. The Pelleted Rotating Disc Spark Method.- D. Atomic Absorption Methods.- References.- Mass Spectrometric Methods..- A. Instrumentation.- B. The Sample.- I. Vapor Pressure.- II. Techniques of Introduction.- III. Purity.- C. Origin of Mass Spectra and their Interpretation.- I. Ionization and Fragmentation of Organic Molecules.- II. The Molecular Weight.- III. Simple Fragments.- IV. Rearrangements.- V. Metastable Ions.- VI. Multiple-Charged Peaks.- VII. Mixtures.- VIII. High Resolution Spectra.- D. Specific Applications.- I. Amino Acids.- 1. Qualitative Spectra.- 2. Quantitative Analysis of Amino Acid Mixtures.- II. Amino Acid Sequence in Peptides.- III. Fatty Acids and Related Compounds.- IV. Alkaloids.- V. Miscellaneous Groups.- VI. Determination of Stable Isotopes in the Intact Molecule.- Appendix I.- References.- Plant Spectra: Absorption and Action..- A. Instrumentation.- B. Light Scatter Phenomena.- C. Absorption Spectra.- D. Action Spectra.- E. Fluorescence Excitation Spectra.- References.- Gefriertrocknung..- A. Die biologischen Probleme der Gefriertrocknung.- I. Das intracellular Gefrieren.- II. Die Vitrifikation.- III. Das extracelluläre Gefrieren.- IV. Die Trocknung.- V. Die Fehlerquellen.- VI. Testmethoden.- B. Die Vakuum-Sublimation.- I. Theoretische Grundlagen.- II. Apparative Ausrüstung.- 1. Der Vakuum-Pumpstand.- 2. Der Trocknungsraum.- 3. Kühleinrichtungen.- 4. Objektheizung.- 5. Meßgeräte.- III. Gefriertrocknungsanlagen.- C. Anwendungen.- I. Gefriertrocknung flüssiger Präparate.- II. Konservierung von Mikroorganismen.- III. Fixation für cytochemische Untersuchungen.- IV. Fixation für elektronenoptische Untersuchungen.- D. Verwandte Methoden.- I. Gefrierkonservierung.- II. Gefriersubstitution.- III. Gefrierschnitte.- Vapour Phase Chromatography..- A. Theoretical Approach.- I. Chromatography in General.- 1. Nature of Stationary Phase: Adsorption vs. Partition.- 2. Mobile Gas Phase : Elution, Displacement and Frontal Analyses.- II. Types of Theories.- 1. Linear vs. Non-Linear Distribution Isotherms.- 2. Ideal vs. Non-Ideal Chromatography.- III. Plate Theory.- 1. Calculation of the Number of Theoretical Plates.- 2. Calculation of the Distribution Coefficient.- 3. Evaluation of a Chromatographic Separation.- IV. Rate Theory.- 1. Eddy Diffusion.- 2. Molecular Diffusion.- 3. Resistance to Mass Transfer.- 4. Temperature, Flow Rate and Pressure.- V. Modifications and Additional Theories.- B. Apparatus Requirements.- I. Detection Systems.- 1. Integral Methods.- a) Titration.- b) Electrical Conductivity.- c) Volume and Pressure Changes.- d) Combustion to Carbon Dioxide.- 2. Differential Detectors - which Consume the Sample.- a) Combustion to Carbon Dioxyde.- b) Hydrogenation to Methane.- c) Flame Emissivity.- d) Hydrogen Flame and Thermocouple.- e) Flame Ionization.- 3. Differential Detectors - which Preserve the Sample.- a) Surface Potential.- b) Dielectric Constant.- c) Impedance of Gas Flow.- d) Heat of Vaporization.- e) Interferometer.- f) Spectroscopy.- g) Radioactivity.- h) Thermal Conductivity - the Katharometer or Diapharometer.- i) Gas Density Balance.- j) High Voltage Ionization.- k) Thermionic Emission.- 1) ? -Ray Ionization.- m) Radio Frequency Detector.- 4. Summary of Detector Characteristics.- II. Gas Phase.- III. Sample Introduction.- 1. Gaseous Samples.- 2. Solid and Liquid Samples.- IV. Stationary Phase.- 1. Column Construction.- 2. Column Dimensions.- 3. Capillary Columns.- 4. Solid Support.- 5. "Active" Solid Adsorbents.- a) Charcoal, Alumina Silica Gel.- b) Molecular Sieves.- c) Tailing Reducers.- d) Chromatothermography.- e) Multiple Columns.- 6. Liquid Phase for GLC.- a) Column Preparation.- b) Selection of the Stationary Phase.- c) Improvement of Peak Symmetry.- V. Temperature Control.- 1. Types of Heating Units.- 2. Programmed Temperature Chromatography.- C. Techniques.- I. Sample Preparation.- 1. Removal of Water.- 2. Esterification.- II. Fraction Collection.- III. Sample Identification.- 1. Use of Standards.- 2. Homologous Series Plots.- 3. Detectors with Different Responses.- 4. Auxiliary Instruments.- 5. Electron Affinity Spetroscopy.- 6. Functional Group Classification.- IV. Quantitative Analysis.- 1. Peak Heights.- 2. Peak Areas.- 3. Overlapping Peaks.- 4. Sloping Base Line and Secondary Peaks.- 5. Instrument Correction Factors.- 6. Internal Standard and Internal Normalization.- D. Applications.- I. Analytic Applications.- 1. Carbon Dioxide and Oxygen : Respiration and Photosynthesis.- 2. Hydrogen, Hydrogen Sulfide, Methane and other Fermentation Gases.- 3. Olefins and Saturated Hydrocarbons.- 4. Nitrogen, Nitrous Oxide, Nitrogen Dioxide and Nitric Oxide.- 5. Ammonia, Organic Amines and Amino Acids.- 6. Alkaloids, Indoles, Purines and Related Compounds.- 7. Carbohydrates.- 8. Lipids, Fatty Acids.- 9. Mono and Dicarboxylic Acids of Low Molecular Weight, and their Derivatives.- 10. Alcohols, Aldehydes, Ketones and Miscellaneous Esters.- 11. Phenyl Propanoid Compounds, Aromatic Acids, Phenols and Related Substances.- 12. Terpenes.- 13. Sulfur Compounds.- 14. Steroids.- 15. Miscellaneous Compounds.- II. Preparative Gas Chromatography.- E. Conclusion.- References.- Ion-Exchange Chromatography..- A. Ion-Exchange Materials.- I. Fundamental Properties of Ion-Exchange Resins.- 1. Chemical Structure.- 2. Physical Properties.- a) Cross-Linking.- b) Exchange Capacity.- c) Particle Size.- II. Ion-Exchange Celluloses.- B. Theory of Chromatographic Procedures.- I. Elution Analysis.- 1. Theory of Elution Analysis.- 2. Conditions for Successful Elution Analysis on Ion-Exchange Resins.- II. Displacement Development.- 1. Completely Ionized Components.- 2. Incompletely Ionized Components.- Comparison of Elution and Displacement Methods.- III. Frontal Analysis.- C. Apparatus.- D. Experimental Procedures.- I. Purification of Ion-Exchange Resins.- II. Preparation of the Column.- III. Operation of the Colum…