Question

L. Choose the correct answer: 1) Reversed phase liquid chromatography refers to (a) the use of non polar solvent as the eluent in HPLC. (b) the use of polar material as the stationary phase in a chromatographic column. the use of non-polar material as the stationary phase in a chromatographic column 2) A solute with a retention time of 325 seconds has a base width of 15 seconds. The column is 11.5 cm long. The c (2 points) olumn has how many theoretical plates? (a)7510 theoretical plates. L (3 points) (b) 625 theoretical plates. (c) 15.3 mm. 1- Refer to the following chromatogram: 3 8 5 6 tM 10 9 6 9 1O 1 12 13 1415 16 2 3 7 8 Time (min) a. Which 2 peaks give the lowest value of the resolution factor, Rs? (Hint: No calculations are required, but briefly explain your answer.) ress ctor we 2,becaum the peaks an not . Estimate approximately the resolution, Rs, for the two peaks 5 and 6.

Answer 1

Ans 1 : c) the use of non polar material as the stationary phase in a chromatography column.

The reversed phase liquid chromatography ustilises a hydrophobic or a non polar solvent as its stationary phase.

The polarities of the mobile and stationary phases have been reversed here as compared to the normal phase chromatography , hence the name.

So in this procedure , the polar hydrophilic molecules tend to elute faster , whereas the hydrophobic organic molecules stay back bonded to the stationary phase. The latter will be then eluted by decreasing the polarity of the mobile phase.