Cannabis makes its cannabinoids as carboxylic acids, marked with an "A" (THCA, CBDA, CBGA, CBCA, THCVA). The acids are the biosynthetic products of the trichome enzymes. Their neutral forms (THC, CBD, CBG, CBC, THCV) appear when the carboxyl group leaves as CO2 during decarboxylation, mostly through heat, slowly through storage.
In practice
Raw and cured flower is mostly acids; smoke, vapour and cooked products are mostly neutrals. That's why a flower COA lists both and why labels report calculated "total THC". The distinction also drives lab method choice: HPLC measures the acids and neutrals separately at room temperature, while GC heats the sample, converts most acids in the inlet and reports neutrals unless the sample is derivatised first.
Neutral = acid × conversion factor: about 0.877 for THCA to THC and CBDA to CBD, 0.878 for CBGA to CBG and 0.867 for THCVA to THCV (molecular weight ratios).
Don't confuse with
- Total THC: a calculated combination of acid and neutral.
- Degradation products (CBN, CBL): formed by oxidation or light, not by decarboxylation alone.
THCA (tetrahydrocannabinolic acid) is the acid cannabinoid that drug-type cannabis makes in its trichomes; heat or time decarboxylates it into THC, losing about 12% of its mass.CBGA (cannabigerolic acid) is the precursor cannabinoid that the plant converts into THCA, CBDA or CBCA, formed by joining olivetolic acid to geranyl pyrophosphate.THCVA (tetrahydrocannabivarinic acid) is the acid precursor of THCV, made in trichomes from CBGVA when the plant's pathway starts from divarinic acid instead of olivetolic acid.THC (Δ9-tetrahydrocannabinol) is the neutral, decarboxylated cannabinoid mainly responsible for cannabis's reported intoxicating effects; the living plant makes it almost entirely as THCA.CBD (cannabidiol) is a non-intoxicating neutral cannabinoid formed when CBDA decarboxylates; hemp-type and CBD-dominant cannabis make it mainly as CBDA in their trichomes.CBG (cannabigerol) is the neutral, decarboxylated form of CBGA, the cannabinoid precursor; most plants convert nearly all of it onward, but some cultivars are bred to accumulate it.THCV (tetrahydrocannabivarin) is the propyl-chain (C3) analogue of THC, formed by decarboxylating THCVA; it is a minor cannabinoid in most cultivars but notable in some African-derived lines.Decarboxylation is the loss of a carboxyl group as CO2 that turns acid cannabinoids such as THCA and CBDA into neutral THC and CBD, quickly with heat, slowly with time.Total THC is a calculated figure, Δ9-THC plus 0.877 × THCA, estimating the maximum THC a sample could yield after full decarboxylation.Gas chromatography (GC) separates volatile compounds in a heated gas stream; it is used for terpenes and residual solvents and decarboxylates acid cannabinoids in its hot inlet.HPLC (high-performance liquid chromatography) separates compounds dissolved in a liquid under pressure; it is the standard cannabis potency method because it measures acid cannabinoids without heating them.
