Article by Marco Troiani, Cannabis Culture
Decarboxylation is a process by which carbon dioxide (CO2) leaves a stable molecule and floats off as a gas. Atoms in a molecule can be thought of like billiard balls, with each one having a size, weight, and exact position. As these atoms float away, the substance left behind will become lighter, like a dry towel being lighter than that same towel soaking wet. The idea is that as the CO2 leaves, the weight left behind is reduced.is a process in which carbon dioxide (CO2) leaves a stable molecule and floats off as a gas. Atoms in a molecule can be thought of like billiard balls, with each one having a size, weight, and exact position. As these atoms float away, the substance left behind will become lighter, like a dry towel being lighter than that same towel soaking wet. The idea is that as the CO2 leaves, the weight left behind is reduced.
As we can see in the illustration, the weight of the CO2 is lost as it floats away, leaving less mass and weight of substance than before decarboxylation occurred. Decarboxylation typically occurs when a substance is heated, but it can also be caused by exposure to certain frequencies of light, and catalyzed by certain substances like molecular oxygen in the air.
If the weight of the molecule before and after its decarboxylation is known, then a percent of mass lost in decarboxylation can be calculated. If the CO2 contributes 10% of the weight of a molecule, than 90% of the mass remains after decarboxylation. This would mean that continuously heating 100 g of this substance would eventually yield 90 g of the decarboxylated substance, as the remaining 10 g represent the weight of CO2 which gassed off.
Cannabis only has the ability to produce cannabinoid acids, like THCA and CBDA. THC is only created when the buds are decarboxylatedized outside the plant. This decarboxylation is usually achieved by the heat of fire when smoked, or from the heat of baking in edibles. Most cannabinoids lose approximately 12.3% of their mass upon decarboxylation. That means that if you had 100g of crystalline isolate of a cannabinoid acid, such as THCA, after decarboxylation you would have 87.7 grams left of THC.
This knowledge is important for people decarboxylating cannabinoids by themselves, particularly producers of cannabis-infused edible products and hash oil producers that wish to sell decarboxylated oil. This is also important for brokers of raw cannabis products such as cured cannabis flower, who must either report the value of the cannabinoid acid directly observed by the testing lab, use the theoretical conversion, or display both.
The labeling issue with raw flower is not as easy as it seems at first glance. Let’s consider a typical example of THC-dominant cannabis. A lab will test the flower and find 26% THCA and 3% THC. 3% THC occurs because a small amount of the cannabinoid acids are decarboxylated by air and sun before harvesting and curing. The smaller amount of THC observed directly by the lab typically indicates that the cultivator has submitted fresh cannabis that has been protected from light and exposure. A higher THC content indicates that the cannabis flower has undergone more exposure and is therefore not as fresh as flower with a low THC content.