CAIE A-Level Chemistry 37.2.3 Retention Time and Stationary-Phase Interaction
Practise explaining why components have different GLC retention times through stationary-phase interactions.
- Syllabus
- 2028–2030
- Course
- Chemistry 9701
- Level
- A2
Exam points
- link a longer retention time to stronger attraction or intermolecular forces with the stationary phase
- link a shorter retention time to weaker stationary-phase interaction and more time in the moving gas
- compare the components named in the question rather than treating retention time as a fixed molecular property
37.2.3—Retention times question 1
A polypeptide formed from four amino acids, A, B, C and D, is completely hydrolysed and then analysed by gas-liquid chromatography.
The chromatogram produced is shown in Fig. 8.2.
Fig. 8.2
The number above each peak represents the area under the peak.
The area under each peak is proportional to the mass of the respective amino acid in the mixture.
The retention time for amino acid D is the longest.
Explain why D has a longer retention time than the other amino acids A, B and C.
All question bank results loaded