HPLC

[5words]

Since most HPLC uses a hydrophobic stationary phase; TPR , for instance, commonly use the term to refer to RP-HPLC since are the majority are Reverse Phase and the Normal Phase is seldom used. Hence this question, The passage nor the Q stem specify which type of column is used. So can one chose among the answer choices here, and i swear if this was TPR, the answer choice would have being A? but EK's B.


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So question, am i wrong for assuming that the HPLC, when not specified, is supposed to have non-polar stationary phase (since most HPLC are RP)

@aldol16 @Pono_0001

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[aldol16]

This is a sticky one because I don't know which definition the AAMC will use. You are correct in saying that in practice, we generally use non-polar (C18) columns and do reverse-phase HPLC. We start out with 100% water and then slowly add acetonitrile into the solvent composition. That's by far the most common way to run HPLC. My gut tells me that this problem is isolated to the test prep companies who don't have all that great of chemists writing their problems. The AAMC will likely specify whether it's a normal-phase or reverse-phase separation because something like this probably wouldn't pass quality control.