Question

Aspirin is more polar than ibuprofen. In reverse phase liquid chromatography, what is the elution order? a. aspirin will elute before ibuprofen b. aspirin will have a longer retention time than ibuprofen c. aspirin will elute after ibuprofen d. ibuprofen will have a shorter retention time than aspirin

Answer 1

In reversed-phase HPLC the order of elution is the opposite of that in a normal-phase separation(with more polar solutes eluting first in normal . Increasing the polarity of the mobile phase leads to longer retention times. Shorter retention times require a mobile phase of lower polarity.

So,according to this concept,the answer is option (a) i.e. aspirin will elute before ibuprofen. and option (b) i.e. aspirin will have a longer retention time than ibuprofen.

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