Chapter 23 - Gas Chromatography

Question 0

How does gas chromatography work?

Answer 0

Analyte is injected into a long tubular column and is moved by a carrier gas while adsorbing on column walls. Low adsorbing analyte is detected before high adsorbing analyte.

Question 1

In gas chromatography, what is the mobile phase called?

Answer 1

A carrier gas

Question 2

In gas chromatography, what do open tubular columns offer?

Answer 2

• higher resolution
• shorter analysis times
• greater sensitivity
• lower sample capacity

Question 3

What are the effects of open tubular columns inner diameter on resolution?

Answer 3

The narrower the column, the greater the resolution.

Question 4

What are the effects of varying the column length in gas chromatography?

Answer 4

A longer column provides a higher resolution.

Question 5

In gas chromatography, what are the effects of varying the thickness of the stationary phase?

Answer 5

The effect of thickness in stationary phase open tubular columns is that increasing the thickness, increases the retention time and increases resolution of the early - eluting peaks.

Question 6

What is the Kovats retention index?

Answer 6

A variable that relates the retention times of a solute to the retention times of linear alkanes.
For a linear alkanes it is equal to 100x the carbon number.

Question 7

In gas chromatography, what is a temperature program?

Answer 7

A temperature program raises the temperature of a column during separation to increase the solute vapour pressure and decease retention times of late eluting components.