Gas Phase Chromatography

1. Theory of Capillary Chromatography.- The separation process in the capillary—The retention time as a characteristic value—Column performance of the capillary—The van Deemter-Golay equation—Optimum linear gas velocity and minimum HETP—Load capacity of the capillary—Summary of the factors which influence good column performance—Film thickness dF—Type and velocity of carrier gas.- Analytical task, time of analysis, and column performance required.- The required column performance—Determination of the number of theoretical plates—The required number of theoretical plates—Rapid analyses—The smallest possible length of capillary —Effect of temperature.- 2. Methods and Apparatus.- The carrier gas.- Type of gas—Gas purification.- Gas flow rate measurement and flowmeters.- Gas throughput measurements at the sample injector—High precision measurements.- The capillary.- Materials for capillaries—Production of long capillaries—Copper capillaries—Glass capillaries—Testing the capillary.- Flow of gas in a capillary.- Testing the capillary for cleanliness—Cleaning the capillary.- Coating the capillary.- The plug method—Film thickness and its control—The auxiliary solvent—Rate of coating—Adjustment of the gas flow rate needed for coating—Coating by the plug method using a microelectrolytic cell—Quantity of coating solution required—Evaporation and ageing of the solution film—The evaporation method—Concentration of coating solution and film thickness—Choice of solvent—Rate of coating—Coating temperature—Ageing of the capillary coating.- The sample injector.- Injection of gaseous substances—Injection of liquids—Injection of solids.- The splitter.- Summary on sample injection.- The detector.- The microflame ionization detector—Principle—Theory.- Amplifiers.- Measurement of amplifier sensitivity and linearity—Amplifier noise—Calculation of the amplifier sensitivity—Checking the sensitivity of the detector—Calculation of the factors for quantitative analysis.- Constructional details of the MFID.- Jet form Jet orifice—Insulated or earthed jet?—Collector electrode holder—Conductor cable, screening and earthing—Ionization voltage—Should the jet be negative or positive?—Ignition of the flame—Triode variant for a.c. operation of the MFID—Heating of the detector chamber—Production of optimum operating conditions—Base line stability—Conclusions —Stability of sensitivity.- ?-ray ionization detectors.- Principle—Sensitivity—Variants of the ?-ray ionization detector—Connection to the recorder—Constructional details—Sensitivity to disturbance.- 3. Applications.- Qualitative analysis.- Methods of identification—Direct chromatographic identification—Identification with selective preliminary separation—Preliminary chemical separation—Physical identifications—Identification by synthesis—Qualitative analysis with the aid of literature data.- Quantitative analysis.