Research published in Cannabis and Cannabinoid Research suggests the way CBD extracts are stored could have an effect on how much THC the final product contains.
It was already known that, when CBD is stored in an acidic environment, some of it can cyclize to form THC.
If the amount of THC impurities in stored extracts turned out to be significant, this could have implications for the ways commercial producers package and store CBD products.
While CBD extracts are typically derived from hemp, biotech companies are striving to develop a process for producing synthetic CBD that will lower production costs.
The reaction used to manufacture synthetic CBD also results in additional byproducts, including trace amounts of D9-THC and D8-THC. These impurities need to be removed by chromatography if a pure CBD solution is required.
The authors of the recent study looked at the stability of both synthetic CBD and plant-derived CBD extracts, using liquid chromatography and mass spectrometry to analyze samples stored under various conditions.
This included accelerated stability tests during which CBD solutions were stored at temperatures and relative humidities that were higher than one would typically store CBD solutions.
They found that neither newly synthesized nor hemp-extracted CBD samples contained THC impurities.
But when samples were stored for three months in the dark and at room temperature, they contained small amounts of both D9-THC and D8-THC.
The authors surmise the presence of carbon dioxide and moisture led to the conversion of small amounts of CBD to THC.
In addition, they conclude there should be no significant conversion to THC of pharmaceutical CBD products if proper storage conditions are followed.
Even under the accelerated stability tests, the maximum concentration of combined ?9-THC and ?8-THC was 0.15% – below the threshold required by regulations in the US and Canada.
CBD producers might need to assess whether proper storage instructions – refrigeration and a best-before date, for example – might minimize the presence of THC impurities in commercial products.
Stability tests would show whether this is the case.