you can absolutely generate a repeatable “terpene profile” using a liquid injection.
It should be more quantitative than a manual headspace injection.
the terpenes WILL dissolve in ethanol.
they will also fly in the GC however you get them into the injector.
given that they are in your matrix at 20-200 fold lower concentration than the cannabinoids, you have to load more (I used to do 1g flower rather than 100mg). [THIS is where just taking the volatiles helps…]
figuring out what the various peaks actually are? that will require a liquid injection of your standards.
I figure that the Edibles analysis using new SRI GC configuration backflush capabilities would allow backing the cannabinoids out rather than driving them (and the gunk that elutes after the cannabinoids) at your injector. haven’t gotten around to trying it yet.
you will certainly loose some (presumed “terpene”) peaks to your (massive) solvent peak…starting at 30-50C helps there.
not saying that headspace isn’t the RIGHT tool. just that “run what you brung” will get the job done.
HPLC terpene analysis: https://www.tandfonline.com/doi/abs/10.1081/JLC-120014270