Chapter 2

Lead topics for Tutorial 2 (Sections 2.1 to 2.4.3)

1. What are the limits of gas chromatography, i.e., when and why should GC be used instead of another chromatographic separation technique[80]

2. Review and compare the five main column types used on gas chromatography [81-83]

3. How is the carrier gas chosen in GC? Discuss the parameters that govern the choice of an appropriate carrier gas for use with thin film and thick film open tubular columns. [83-86]

4. Why are hydrocarbon phases not commonly used in GC?[87-88]

5. How does the retention of a fluorocarbon phase compare to a hydrocarbon phase of similar molecular structure, and what are the implications of this difference for the separation of thermally labile solutes and

compounds with high boiling points? [88]

6. Discuss the advantages and limitations of ether- and ester-based stationary phases for GC? [89-90]

7. What kind of organic salts are used as stationary phases in GC and what are the unique selectivities that can be obtained when using salt-based stationary phases? [90-91]

8. Discuss the two principally different techniques that are used to immobilize polysiloxane stationary phases in open tubular columns and the advantages of immobilized, crosslinked the stationary phases [91-97]

9. Discuss the concepts of solvent strength/polarity and selectivity in GC [97-98]

10. Discuss the applicability, advantages, and disadvantages of solid stationary phases in GC [111-112]

11. Consider the similarities between inorganic adsorbents when used as stationary phases in solid phase GC and normal phase LC [113]

12. Discuss the selectivities attainable with the various classes of sorbents used in solid phase GC and the criteria for proper selection of a phase for a particular application. When could it be relevant to regress to a packed column for reasons of selectivity in GC?[113-117]

13. What are the advantages and drawbacks of host/guest phases, bonded phases, and metal interactive phases in gas chromatography? [117-120]

14. Discuss interfacial adsorption (gas/liquid and liquid/support) in relation to stationary phase properties and phase loading (film thickness in an open tubular column) .[120-121]

15. Clarify the three principally different ways of accomplishing a separation system in GC that is based on a binary stationary phases mixture. Which of these three principles are applicable to packed and open tubular

columns (and why), and how are open tubular column systems with coupled columns optimised?....[125-129]

16. Flow and temperature programming are the two techniques used to overcome the “general elution problem” in GC. What are the pros and cons of these two approaches, and in what situations is one technique preferred over the other. Further, discuss the optimization of thermal programming in GC. .[129-133]