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Chemistry LibreTexts

Chromatography - In-class Problem Set #3

Problem #1 – Fundamental Resolution Equation

After completing this problem, the student will be able to:

  1. Describe each of the different ways in which the number of plates on a chromatographic column can be increased.
  2. Explain and rationalize whether there any tradeoffs associated with these changes?
  3. Describe ways in which the separation factor can be increased.
  4. Explain why there are limits to the effect that increasing the separation factor has on chromatographic resolution.
  5. Describe ways in which the retention factor can be increased in gas and liquid chromatography
  6. Explain and rationalize whether there any tradeoffs associated with changes designed to increase the retention factor.
  7. Explain why there are limits to the effect that increasing the retention factor has on chromatographic resolution.
  8. Examine a chromatogram with unacceptable levels of resolution and determine which term of the three in the fundamental resolution equation is the best one to alter and the best way to first go about altering it.

Problem #2 – Fundamental Resolution Equation

After completing this problem, the student will be able to:

  1. Recognize peaks in a chromatogram that have either too small or too large of a retention factor.
  2. Describe a way in gas chromatography to optimize the retention factor for each component of a multicomponent mixture.
  3. Describe a way in liquid chromatography to optimize the retention factor for each component of a multicomponent mixture.

After lecture material on the basics of liquid chromatography, the student will be able to:

  1. Draw and describe the basic setup of a liquid chromatograph.
  2. Draw and describe the operation of a reciprocating small-volume pump with inlet and outlet check valves.
  3. Describe the operation of and flow paths through a liquid chromatographic injection valve.

After lecture material on steric exclusion chromatography, the student will be able to:

  1. Describe the influence of the pore size on the separation
  2. Rationalize why larger molecules elute earlier in steric exclusion chromatography
  3. Rationalize why steric exclusion separations occur in one column volume
  4. Describe the procedure through which steric exclusion chromatography can be used to determine the approximate molecular weight of a substance
  5. Explain why steric exclusion chromatography is actually a size-based rather than weight-based method