Gas Chromatography

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Preparing the Chromatograph
Cleaning the Syringe
Drawing a Sample into the Syringe
Injecting a Sample
Additional Topics
Interpreting the Chromatogram
Calculating the Area
Related Modules
Chart Recorder
Paper Chromtography
Thin-Layer Chromatography

Calculating the Area


The area of a peak is proportional to amount of the compound that is present. The area can be approximated by treating the peak as a triangle. The area of a triangle is calculated by multiplying the height of the peak times its width at half height.

IMAGE. A representative chromatogram.

For example, using a ruler, the Peak A was measured to have a height of 28.2 mm and a width at the half-height of 3.5 mm. Peak B has a height of 41.2 mm and a width at half-height of 4.5 mm. Therefore, the areas of the peaks can be calcuated as follows:

Using these areas, the percent of each compound in the sample can be calculated.<

In addition, the ratio of B to A can be found using the areas.