1. Consider the following changes that could be applied to the operating parameters for a chromatogram set up to carry out high-performance liquid chromatography (HPLC) with a polar stationary phase and a non-polar mobile phase:
I decreasing the viscosity of the mobile phase
II using a more tightly packed stationary phase
III using a mobile phase that is more polar than the stationary phase

Which of the changes would be most likely to reduce the retention time of a sugar in the HPLC?
A. I only
B. I and III only
C. III only
D. II and III only

Solution

2. The composition of fatty acids found in an egg yolk sample is given in the table below.

The composition of fatty acids in an egg yolk was determined by reacting the fatty acids with methanol to produce methyl esters and then analysing the methyl esters using chromatography. Explain, using the principles of chromatography, how each fatty acid in the egg yolk sample can be identified and the percentage determined

Solution