In the GC composition, C7 would represent all isomers including nC7. This is true for other Carbon Numbers as well. I have cryogenic flash composition data for some samples and they have BTEX compositions. Standard Single Stage Flash (SSF) composition for other samples doesn't include these BTEX composition. They have been reported as C7 total, C8 total...
So when I have to compare different samples to understand compositional variation, they have different composition scheme. I just proposed the above composition to make two different sets of compositions to have a unified composition scheme.
I would like to know whether I need to follow some other procedure.