Analysis of the components of a mixture using gas-liquid chromatography normally involves measuring the
A. Rf values of components, using a gas as the mobile phase.
B. Rf values of components, using a liquid as the mobile phase.
C. retention time of components, using a gas as the mobile phase.
D. retention time of components, using a liquid as the mobile phase.

Solution

Chromatogram 1 was obtained by analysis of a sample of a mixture of two sugars, A and B, using highperformance liquid chromatography (HPLC). Chromatogram 2 was obtained by analysing another sample of
the same mixture by HPLC under different conditions.

Consider the following changes which could be made to the operating conditions for HPLC.
I decreasing the pressure of the mobile phase
II decreasing the temperature
III using a less tightly packed column
Which of the changes would be most likely to produce chromatogram 2?
A. I only
B. II only
C. III only
D. I and II only

Solution