CO2 Extraction. This method is one of the most common ones, it is also very safe. Normally CO2 is a gas. However, with the help of elevated temperature and high pressure, it reaches a supercritical state, in which its density is like that of a liquid, and its viscosity and surface tension are like that of a gas. This unusual physical substance (fluid) is an excellent non-polar solvent. It allows for extracting the necessary elements from raw materials with the highest accuracy. After reducing the pressure, the waxy substance with high CBD content is separated from the gas, as it returns to its usual gaseous form. This substance has a brilliant golden color. After this, it undergoes additional purification, known as “winterization”. The key task of this process is to remove vegetable waxes from the resulting substance since they cannot be included in some types of products and in general they may be undesirable for the human body. In addition, “winterization” allows drugmakers to remove chlorophyll (a green pigment). Removing oil with CO2 is expensive and requires highly specialized knowledge. However, it is not associated with burning and is significantly safer.
Ethanol Extraction. Ethanol has been used to extract medical substances from plants for a long time. Back in the middle of the 19th century, the American Pharmacopoeia recommended hemp-based alcoholic tinctures to treat mood collapses, hemorrhages, pain, and neuralgia (a disease of peripheral nerves, which is manifested as intense, intermittent pain). Such tinctures were actively used by the population until the 1930s when a ban on cannabis-based products was imposed by US law. However, these tinctures continued to be used underground, especially in the communities where Latin Americans lived. Ethanol destroys hydrogen bonds and weakens the electrostatic interaction of lipids and proteins. It should be borne in mind that alcoholic extracts from plant material, as a rule, contain resinous substances, pigments anthocyanins, carotenes, chlorophyll, flavones, etc. (waxes, sterols, fats, balms, etc.). One of the currently popular products obtained by this method is Rick Simpson Oil. However, it contains all the cannabinoids and not just one cannabidiol, including a small amount of THC. Because of the possibility of the psychoactive action of Rick Simpson Oil and the presence of other substances in its composition, manufacturers recommend using it in very small dosages (one dose should not exceed the rice grain size).
Hydrocarbon Extraction. This technology involves the use of hydrocarbon solvents like butane (C₄H₁₀), hexane (C₆H₁₄), propane (C₃H₈), or their mixtures. If the proper implementation of the technique is ensured, it allows for getting a pure product, which is properly separated from unwanted substances like chlorophyll. The main advantage of this method is a high degree of purification and separation of excess components. The product retains a unique smell and all therapeutic properties. However, hydrocarbons are flammable substances that can also have a neurotoxic effect. If the product is poorly cleaned, it can both explode in case of non-compliance with safety measures and cause harm to health.
Olive and other oils. These substances may be used to get homemade CBD oil. Oils are a much safer choice than solvents which can easily get inflamed and cause a conflagration. The study by the Italians L.L. Romano et al. (2013) evaluated the effectiveness of five solvents, including petroleum ether, ethanol, naphtha, and oil from olives. They showed practically the same efficacy, but olive oil methods were considered safer due to the absence of risk of blowing up. Two techniques based on olive oil usage were described. The first involves olive oil and water, which should be heated in a water bath (with added cannabis) for an hour. To separate oil and water, the solution should be put in the freezer. According to another technique, olive oil is used solely for extraction. Cannabis (10 g) and the oil (100 mL) should be heated in a water bath for 2 hours. Then just collect the oil which has become rich in CBD.