Gas Chromatography – Section 1

11. A retention gap is placed between the injector and the front of the column to

A. retain contaminants and prevent them from reaching the column
B. retain the sample and release it gradually to the column
C. prevent backflush of the injected solution
D. all of the above

Correct Answer: A. retain contaminants and prevent them from reaching the column

12. Which of the following detectors give mass flow-dependent signals?

A. Electron capture detector
B. Field ionization detector
C. Thermal conductivity detector
D. All of the above

Correct Answer: B. Field ionization detector

13. Headspace analysis is carried out in order to

A. analyze volatile compounds from solid or liquid samples
B. determine the psychological state of the tutor
C. analyze the column contents ahead of the sample
D. determine non-volatiles

Correct Answer: A. analyze volatile compounds from solid or liquid samples

14. A split injection is carried out by

A. splitting the sample into smaller portions to inject sequentially
B. splitting the sample into smaller portions to inject at the same time through parallel ports
C. splitting off some of the samples so that it does not enter the column
D. none of the above

Correct Answer: C. splitting off some of the samples so that it does not enter the column

15. What does the retention factor, k’, describe?

A. The distribution of an analyte between the stationary and the mobile phase
B. The migration rate of an analyte through a column
C. The velocity of the mobile phase
D. All of these

Correct Answer: B. The migration rate of an analyte through a column

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