Gas speed at which the gas moves, the

Gas chromatography is a useful
method in analytical chemistry used to isolate and evaluate a specific compound
that has the ability to vaporize without decomposing, contained within a
matrix. The gas chromatograph can be used in a variety of situations such as
analyzing the purity of the compound in question, or separating the individual components
of a mixture and determining the amount of compound you have in relation to the
mixture. A gas chromatograph is comprised of several main components: a carrier
gas which is most often helium due to its inert nature, a flow valve that
controls the speed at which the gas moves, the column which is a long piece of
tubing made of either steel or glass, and the detector which is comprised of
electrodes near a hydrogen flame that measures differences in potentials as the
hydrocarbons pass through it. In Gas chromatography, you have two distinct
phases, mobile and stationary. The mobile phase occurs in
gas state while the stationary phase is a liquid coating along the walls of the
column. Compounds of interest are separated due to the difference in their
chemical and physical properties. As the various analytes travel through the
column, they are each impeded by the process of adsorption onto the column
walls. How fast an analyte is able to travel through the column depends on the capacity
of adsorption, which as mentioned before depends upon its chemical and physical
properties. Due to this, each compound will therefore reach the detector at
different time periods. The time it takes for this to happen is referred to as
the retention time. The main focus of
this experiment is to obtain the retention times of C16, C18,
and C20 individually, and to then figure out what operating
conditions are ideal to separate the 3 alkanes in a single solution of hexane by
variation of the mobile phase velocity through the adjustment of the column
head pressure. It would be expected that as the CHP decreases the retention
times of the individual alkanes become more distinguishable (narrower peaks)
but at a cost to the resolution of the peaks on the graph. To test these
rationales, I will be using the following formula: