Hemp is a plant that has been used for many years for medicinal, cosmetic, nutritional and industrial purposes. Its use was banned in many places in the past, but today it is allowed for medical purposes in most European countries. It is known for its effects on the nervous system and the immune system, for example in pain and inflammation. These pharmacological properties are mainly characteristic of cannabinoids, which are molecules found in all parts of the plant. With appropriate solvents, they can be extracted from the plant and used. Within master thesis, we focused on the optimization of cannabinoids ethanol extraction.
First, we performed ethanol extraction of cannabinoids from dried flowers of industrial hemp and determined the content of cannabinoids in different fractions of the extract. It turned out that their content is approximately the same in all layers in the flask.
We continued with the extraction profile, initially looking to determine if the amount of cannabinoids extracted varies with the temperature of the extraction solvent and at what time point the cannabinoid content is highest. First, a non-ground drug was used, and the results of the extractions were quite incomparable. Therefore, we further homogenized the drug. We determined the influence of ethanol volatility on the content of cannabinoids in the supernatant, as well as the influence of shaking and ultrasonic homogenization on the extraction efficiency. The results showed that for higher extraction efficiency it is better to use a homogenized drug, a sealed container and include shaking.
Since the extraction efficiency after the previous experiments was still only slightly more than 75%, we tried repeatedly rinsing the drug with ethanol and wringing the drug. The extraction method was improved by wringing the drug fo approximately 15%, while repeated washing of the drug did not contribute to greater extraction efficiency.
Finally, with the help of the Design of experiments approach and the Modde program, we set up the extraction model. We monitored the influence of the extraction time, the temperature of the solvent during extraction and the use of an ultrasonic homogenization on the extraction efficiency, the proportion of cannabidiol, cannabidiolic acid and impurities in the extract. We found that longer time, higher temperature and longer ultrasonic homogenization during extraction increase the extraction of other substances and also of the cannabinoids, while optimal extraction of cannabinoids takes place at low temperatures (-24 °C), medium time (1-4 min) and without ultrasonic homogenization.
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