37.2.2—Gas / liquid chromatograms

In a gas chromatogram, each resolved peak represents a component and its retention time helps identify it. The peak area is proportional to the amount detected, so relative areas estimate percentage composition when detector response factors are comparable.

Add the relevant peak areas, then divide each area by the total area and multiply by 100. Do not use peak height unless the method specifically validates it.

Peak areas 20, 30 and 50 give estimated compositions of 20%, 30% and 50%.

A larger retention time does not mean a larger percentage; time identifies the component, while area estimates amount.