Question-2: In an IILPC analysis, a reverse phase column is being used with a so

Question

Question-2: In an IILPC analysis, a reverse phase column is being used with a solvent gradient, starling with solvenLA and increasing uc concentralion of solvent B over Lime The program starts with 50% A and 50% R and runs linearly, reaching 10()% R at 20 min. Explain which f the two solvents is more polar. A or R and why? Question-3: Predict the elution order of the following compounds in reverse phase and in normal phase chromalography "n heplane, heptanol, and toluend nitrobenzen, benene, and phenol Find the chemical formula ofthe compounds · Rank them in order of increasing or decreasing hydrophobicity. Ideally, use octanol-water partition coetficient (Kow) data when available -Determine the elution order for nmal and reverse phase HPIC

Explanation / Answer

Question 2:

In a reversed-phase chromatography, the packing material (stationary phase) will be non-polar, whereas the eluent (mobile phase) will be polar.

Since the program starts with 50% A and 50% B, and the 'B' reaches 100% within 20 min, the solvent B is more polar.

Question 3:

In a normal-phase chromatography, the stationary phase is polar, whereas the mobile phase is non-polar.

(i) The order of elution in normal-phase chromatography: n-heptane > toluene > heptanol.

The order of elution in reversed-phase chromatography: heptanol > toluene > n-heptane.

(ii) The order of elution in normal-phase chromatography: benzene > nitrobenzene > phenol

The order of elution in reversed-phase chromatography: phenol > nitrobenzene > benzene

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