Can GC measure acidic cannabinoids?

Yes. The common assumption is that gas chromatography can only measure neutral cannabinoids because the heat of injection converts acidic forms (THCA, CBDA) into their neutral equivalents (THC, CBD). That is true for standard GC analysis without any sample preparation step. But with derivatisation, GC can measure both forms.

How derivatisation works

Derivatisation is a sample preparation step applied before injection. It chemically stabilises the acidic cannabinoids so they no longer convert to their neutral forms when heated in the GC injector. The derivatised acidic and neutral cannabinoids then separate on the column and produce distinct peaks on the chromatogram.

This gives you three pieces of information from a single run: the concentration of neutral cannabinoids (THC, CBD), the concentration of acidic cannabinoids (THCA, CBDA), and the total available cannabinoid content.

What is total available cannabinoid content?

Total available cannabinoid is the sum of the measured neutral cannabinoid plus the amount that would result if all the acidic form were decarboxylated. It represents the maximum potency the product could deliver if all acidic cannabinoids were converted.

Why not just use HPLC?

HPLC is the other common approach for measuring acidic and neutral cannabinoids separately. It operates at lower temperatures, so acidic forms do not convert during analysis and no derivatisation is needed.

GC with derivatisation offers shorter run times, lower operating costs, and simpler maintenance than HPLC. For laboratories that already run a GC for terpene, solvent, or pesticide work, adding derivatised cannabinoid analysis keeps everything on one platform rather than introducing a second instrument type.

The same FID and EL-5 column configuration used for potency, terpene, and pesticide testing on the 200 Series GC handles derivatised cannabinoid analysis as well.

Which approach is right for you?

If your laboratory already uses or is planning to buy a GC, derivatisation gives you acidic and neutral cannabinoid measurement without needing a separate HPLC system. If you already have HPLC capability and do not need GC for other analyses, HPLC remains a valid approach.

Want to discuss which method fits your workflow? Get in touch with the team.