Monday, 2 May 2011

Gas Chromatography

Students observing very thin gas column coil

Today one of the tutors, chemistry teacher Naomi Clark from Christies Beach High School assisted the SMAF chemistry class by demonstrating the Vernier Mini gas chromatography. In Gas Chromatography an inert carrier gas serves as the mobile phase that elutes components of a mixture from a column containing an immobilised stationary phase. The uses of gas chromatography are diverse.
Naomi Clark

Naomi injected a sample of the ester (an organic compound) as a liquid into the gas chromatography which was immediately vaporised by heating. The mobile gas phase then carried the sample into the column contained in the oven. The components of the sample separated on the column and are then carried to the detector where a response occurs. 

Organic compounds flowing out of the chromatography column are seen as a peak on a chromatograph. The amount of time it takes for a compound to exit the column after it is injected is called the retention time. With a GC, a compound can be identified from a mixture of chemicals by its retention time.

Peaks on chromatograph formed

The students were asked to use the chromatograph to analyse whether an esterification reaction occurred between ethanol and acetic acid to produce ethyl acetate (a fruity smelling ester). 

Students smelling ester

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