Photo AI
A high-performance liquid chromatography (HPLC) instrument is set up with a polar mobile phase and a non-polar stationary phase - VCE - SSCE Chemistry - Question 24 - 2022 - Paper 1
Question 24
A high-performance liquid chromatography (HPLC) instrument is set up with a polar mobile phase and a non-polar stationary phase. Three amino acids – leucine, Leu, al... show full transcript
Worked Solution & Example Answer:A high-performance liquid chromatography (HPLC) instrument is set up with a polar mobile phase and a non-polar stationary phase - VCE - SSCE Chemistry - Question 24 - 2022 - Paper 1
Step 1
The order of the retention times, from shortest to longest, for these three amino acids is:
Answer
To determine the order of retention times, we need to consider the polarity of both the mobile and stationary phases in HPLC. Since the mobile phase is polar and the stationary phase is non-polar, non-polar compounds will elute faster than polar ones.
- Leucine (Leu) is a non-polar amino acid, so it will have the shortest retention time.
- Alanine (Ala) is less non-polar than leucine and will thus elute next.
- Asparagine (Asn), being polar due to its amide group, will have the longest retention time.
Therefore, the correct order from shortest to longest retention time is D: Asn, Ala, Leu.