You are now the chemist responsible for describing the efficiency of a newly pro

Question

You are now the chemist responsible for describing the efficiency of a newly produced GC column that is 25 meters long. You do this by injecting an aliquot of an octadecane standard into the column and observing its resultant chromatographic output. What type of chromatography are you performing in this experiment? (2 marks) What would you assume the polarity of the mobile and stationary phases are in this efficiency experiment? Why? (3 marks) You find that the retention time for the standard is 8.22 minutes and the width at half height is 0.047 minutes. The chromatographic peak shape is Guassian. Calculate the number of theoretical plates per length (m) of column in this column. (5 marks)

Explanation / Answer

Use Gas Chromatography (GC) in this experiment.

Gas chromatography is also known as the gas-liquid chromatography in which the stationary phase is in a closed tube or column.

mobile and stationary phases are in this efficiency experiment is given below.

mobile phase:
gas

stationary phase:
liquid/solid

In this Chromatography, compounds are separated on the basis of polarity and molecular size and boiling point.

Calculate the number of theoretical plates per length (m) of column .

N=16*{tr/w}2

=16*{8.22/0.047)}2

=479404.4

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