Question

PART 1:

In a gas chromatography experiment using a non-polar stationary phase

A) solutes are eluted in order of increasing boiling point.

B) solutes are eluted in order of increasing vapor pressure.

C) solutes are eluted in order of increasing polarity.

PART 2: You can improve the separation of components in gas chromatography by

A) raising the temperature of the injection port.

B)raising the temperature of the column isothermally.

C) raising the temperature of the column programmatically.

Answer 1

Solution:-

Part A,

In a gas chromatography experiment using a non polar stationary phase,

c) Solutes are eluted in order of increasing polarity,

Explanation- if the polarity of the stationary phase and compound are simlar,the retention time increases because the compound interacts stronger with the stationary phase, as a result polar compounds have long retention times on polar stationary phases and shorter retention times on non polar columns using the same temperature.

Part- B,

You can improve the separation of components in gas chromatography by,

A) raising the temperature of the injection port,

Explanation- if we increase the column temperature results in very short retention time but also in a very poor seperation because all components mainly stay in the gas phase. However, in order for the separation to occur the components need to be able to interact with the stationary phase. If the compound does not react with the stationary phase, the retention time will decrease, at the same time the quality of the separation deteriorates.