After reviewing the data, it
is evident that from all trials run, the C16 compound was always
detected first. This was then followed by the C18 and C20
compounds. A major reason for this was the size of the molecule in question. As
C16 had the smallest carbon chain size, this meant that its boiling
point was lower, due in part to the decrease in London dispersion forces
between the lining of the column and the molecule, compared to the other two
and therefore has a lower vapor pressure. As significant solute movement takes
place specifically in the mobile gas phase, this meant that the C16
compound travelled the quickest compared to the rest in all runs. It is also
important to note that over the course of all runs done during this experiment,
the peak width obtained from the GC always broadened. This is always an issue
in any type of chromatography. As we have several different compounds of
varying sizes and retention properties, there will always be an “ideal” set up
for the absorption/desorption of said compounds. These pre-set conditions are
quite often not ideal for the elution of the later compounds which will
frequently take too long to reach the detector. A possible way to reduce this
is by a step-by-step change in one of the operating conditions of the
chromatographer. In the case of GC, the programming is set up in such a way so
that the column temperature can be raised at a point in time specific to where
the latter peaks appear allowing for faster transport in the gas phase.



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