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Reverse-phase high-performance liquid chromatography (HPLC) uses a non-polar stationary phase together with a polar mobile phase - VCE - SSCE Chemistry - Question 5 - 2009 - Paper 1
Question 5
Reverse-phase high-performance liquid chromatography (HPLC) uses a non-polar stationary phase together with a polar mobile phase. Which of the following molecules wi... show full transcript
Worked Solution & Example Answer:Reverse-phase high-performance liquid chromatography (HPLC) uses a non-polar stationary phase together with a polar mobile phase - VCE - SSCE Chemistry - Question 5 - 2009 - Paper 1
Step 1
Identify the properties of the stationary and mobile phases
Answer
In reverse-phase HPLC, the stationary phase is non-polar while the mobile phase is polar. Thus, the molecules that are more polar will interact less with the stationary phase and elute faster, while non-polar molecules will interact more strongly and have longer retention times.
Step 2
Analyze each molecule for polarity
Answer
Molecule A is fully alkane, making it non-polar. Molecule B contains OH and NH₂ functional groups, indicating some polarity. Molecule C has an alcohol functional group, which is polar. Molecule D is similar to C with an alcohol and ether functional group.
Step 3
Determine which molecule has the greatest retention
Answer
Among the options, Molecule B is relatively larger and has both hydrophilic (OH and NH₂) and hydrophobic (alkane chain) characteristics, leading to stronger interactions with the non-polar stationary phase, resulting in the greatest retention time.
Step 4