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Chapter 26: Q34P (page 749)

Explain how neutral molecules can be separated by micellar electrokinetic chromatography. Why is this a form of chromatography? Why are micelles called a pseudostationary phase?

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01

Step1: Explain the separation of neutral molecules by micellar electrokinetic chromatography.

When there are no micelles, neutral molecules are all washed through the capillary (electroosmotic velocity). Negatively charged micelles move upstream (electrophoretic velocity), and it takes them more time to reach the detector than the neutral molecules.
Neutral molecule would spend some time being free in a solution and also dissolved in the micelles. Therefore, the net velocity would be reduced by the electroosmotic velocity.

02

Micelles as a pseudo stationary phase.

Micellar electrokinetic chromatography is a form of chromatography because in this case the micelles behave like a stationary phase because their concentration is uniform all way through the capillary.

  • Therefore, micelles are also called a pseudostationary phase

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