CEM 333 QUESTIONS AND ANSWERS
WITH SOLUTIONS 2024
Retention factor - ANSWER Ideally, this should be between 2 and 10 for all analytes in a chromatographic
separation.
retention time - ANSWER Time it takes after sample injection for the analyte peak to reach the detector.
Dead time - ANSWER The time for unretained species to reach the detector.
Stationary phase - ANSWER Immisible and immobile, it is packed within a column or coated on a solid
surface.
Selectivity factor - ANSWER Always greater than 1, it is an indication of the relative affinity of two species
for the stationary phase.
Elution - ANSWER Washing a species through a column by continual addition of fresh solvent.
Eddy diffusion - ANSWER Zone broadening due to the multitude of pathways by which an analyte can
find its way through a packed column.
An FID is insensitive to non-combustible gases such as water and carbon dioxide. - ANSWER True
The technique referred to as �gas chromatography� is actually gas-liquid chromatography since the
stationary phase is a liquid adsorbed on the surface of an inert solid. - ANSWER True
Temperature programming is necessary only for samples containing compounds with a narrow range of
boiling points. - ANSWER False
An air peak is commonly used to determine the dead time when using a TCD detector. - ANSWER True
WITH SOLUTIONS 2024
Retention factor - ANSWER Ideally, this should be between 2 and 10 for all analytes in a chromatographic
separation.
retention time - ANSWER Time it takes after sample injection for the analyte peak to reach the detector.
Dead time - ANSWER The time for unretained species to reach the detector.
Stationary phase - ANSWER Immisible and immobile, it is packed within a column or coated on a solid
surface.
Selectivity factor - ANSWER Always greater than 1, it is an indication of the relative affinity of two species
for the stationary phase.
Elution - ANSWER Washing a species through a column by continual addition of fresh solvent.
Eddy diffusion - ANSWER Zone broadening due to the multitude of pathways by which an analyte can
find its way through a packed column.
An FID is insensitive to non-combustible gases such as water and carbon dioxide. - ANSWER True
The technique referred to as �gas chromatography� is actually gas-liquid chromatography since the
stationary phase is a liquid adsorbed on the surface of an inert solid. - ANSWER True
Temperature programming is necessary only for samples containing compounds with a narrow range of
boiling points. - ANSWER False
An air peak is commonly used to determine the dead time when using a TCD detector. - ANSWER True
