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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
Determine the order of retention times based on polarity
Answer
In HPLC, the retention time of a compound is influenced by its polarity relative to the mobile and stationary phases. Since the mobile phase is polar and the stationary phase is non-polar, non-polar amino acids will elute faster than polar ones. Therefore, in this scenario:
- Leucine (Leu) is non-polar, which means it will have the shortest retention time.
- Alanine (Ala) is moderately polar, so it will elute next.
- Asparagine (Asn) is polar and will retain longer in the stationary phase. This leads to the retention order of Leu, Ala, Asn.
Step 2