3.7 Questions
1. Contrast the advantages and disadvantages of thin layer chromatography (TLC) versus modern HPLC.
2. What does HPLC stand for?
3. What are the advantages of dual reciprocating pumps have over syringe pumps?
4. How much does a basic HPLC system cost?
5. What are the sub-categories of liquid chromatography?
6. What is the difference between normal phase HPLC and reverse phase HPLC? Which is most commonly used today?
7. What chemical factors determine if a chemical will be analyzed in a GC or LC?
8. Can moderately volatile, thermally stable chemical be analyzed on an LC?
9. Why do we filter analyte solutions before injection into an HPLC?
10. Draw a basic HPLC system and label all of the components.
11. Why are pressurized gases used in HPLC?
12. What two preparatory steps must be taken before a solvent can be used as an HPLC mobile phase?
In general, what is the maximum pressure limit of standard HPLC systems?
13. What is the purpose of the proportioning valve? How does this reduce the cost of an HPLC?
14. What is the difference in isocratic and gradient programming? Why is gradient programming sometimes necessary?
15. Why are dual piston pumps preferred over single piston pumps?
16. What is the purpose of a pulse damper?
17. Why are six-port valves used for injecting samples in HPLC?
18. Draw and explain how a six-port valve works.
19. Why are in-line filters used in HPLC systems?
20. What is the composition of the stationary phase and purpose of the guard column?
21. What are common stationary phases used in reverse phase HPLC?
22. Why do chromatographers purchase their analytical columns instead of self-packing their own?
23. How will a poorly packed column affect performance?
24. What is the relationship between performance (resolution) and stationary phase particle size?
25. Compile a list of HPLC detectors and provide a list of chemicals each can be used to analyze.
26. Name three advanced types of LC.
27. Why is U-HPLC superior to standard HPLC?
28. How does IC differ from standard HPLC?
29. What is the purpose of the suppressor column in IC?
30. Draw a suppressor column for cation analysis in IC. Explain how it works. Write all requisite chemical reactions.
31. Although not shown in this textbook, attempt to draw a suppressor column for anion analysis in IC. Explain how it works. Write all requisite chemical reactions.
32. What is a super critical fluid?
33. What types of compounds are usually separated by SCF chromatography?
34. What type of gradient is used in SCF chromatography?
35. Review each of the chromatograms in Section 3.5 and determine what intermolecular force is involved in these attractions.
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