2.7 Questions
1. In approximately what decade was chromatography first discovered?
2. What is the purchased price of a basic GC?
3. What are the four basic types of sample matrices?
4. List and describe the common ways gaseous samples are collected for GC analysis.
5. List and describe the common ways liquid (aqueous) samples are prepared for GC analysis.
6. List and describe the common ways soil and sediments samples are extracted and prepared for GC analysis.
7. How are biological samples prepared for GC analysis?
8. Why are analysts concerned with extraction efficiency when they prepare samples for chromatographic analysis?
9. What chemical characteristics must a chemical have in order to be analyzed by GC?
10. How are derivatizing agents used in GC analysis?
11. Draw a diagram showing all of the components of a basic GC.
12. How are the mobile phase flow rates different between packed column and capillary column GC?
13. What is the most common carrier gas used in capillary column GC?
14. Draw and explain how a split-splitless injector works. Why do we use a combination of splitless and split injection? When would you advantageous or necessary to use a total splitless injection?
15. Why is it important to use a Teflon coated septum in some GC analyses?
16. What is the purpose of the glass liner in the GC injector?
17. What are the typical sizes (diameters and column lengths) of fused silica capillary columns?
18. What are typical injection volumes for capillary column analysis?
19. Contrast the cost of an automatic sampler with the advantages of using one.
20. List the six common types of stationary phases used in GC and describe what types of analytes they can be used to analyze.
21. What are the advantages (and disadvantage) of cross linking the stationary phase coating on a capillary column.
22. List five common GC detectors, give their acronym, list the types of chemicals they are commonly used to detect, and their detection limits.
23. Explain, with drawings, how a thermo-conductivity detector (TCD) works.
24. Explain, with drawings, how a flame ionization detector (FID) works.
25. Explain, with drawings, how an electron capture detector (ECD) works.
26. What is meant by confirmatory analysis in chromatography.
27. For each of the chromatograms shown in Section 2.5, identify the intermolecular force involved in the separation of each class of analytes.
28. Select a compound that can be analyzed by GC (relatively volatile and thermally stable) and use the Internet to find what GC column and temperature program is used in its analysis.
29. Say that you are analyzing a mixture of compounds by GC and that you are having trouble achieving separation of some of them (they co-elute or appear as a shoulder peak). What three major things can you change about your GC to possible improve separation?
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