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Chemistry LibreTexts

Chromatography Set #1

  1. Consider a plot that has the concentration of analyte in the stationary phase on the Y-axis and the concentration of analyte in the mobile phase on the X-axis.

    1. Draw an idealized plot as greater concentrations of analyte are injected into the chromatographic column.
    2. Draw what you suspect would really happen.
    3. What might the peaks look like in the real versus ideal situations?
  2. What term would we use to describe the movement of a molecule in a liquid stationary phase?
  3. What processes would account for the movement of a molecule through a region of interstitial volume in a mobile phase?

  4. Tswett used starch as his stationary phase.
    1. What is the dominant surface functionality of starch?
    2. The two other common solid stationary phases are silica gel (SiO2) and alumina (Al2O3). What do you think are the surface functionalities of these materials?
    3. Draw a plot of the distribution of enthalpies of adsorption for a molecule on the surface of starch, silica gel, or alumina.

    4. What would a chromatographic peak look like on such a phase with such a plot of adsorption enthalpies?
    5. What is the problem with your peak?