It is common for people in the CBD and hemp industry to use words like full spectrum and broad spectrum when talking about extracted CBD oils. When these words are used, they are spoken with a sense of understanding, a general agreement that both parties are talking about the same thing. Is that always true however? In fact is it ever true? What does full spectrum even really mean? In a literal sense, it would imply that it contains the full spectrum of compounds found in the original cannabis plant. However, that can’t possibly be true, or it would be the plant. Therefore, full spectrum has to mean some subset of compounds extracted from the cannabis plant. So are all full spectrum extracts the same? The answer is quite obviously no.

The compounds that are available in any given “full spectrum” extract depend on a number of factors including: the strain that is being used, the way the strain was handled prior to extraction, the type of solvent used for extraction, the length of time of the extraction, the temperature and pH of the extraction as well as a variety of other system dependant factors such as input of mechanical energy. All of these different variables create a good deal of room for variation in the produced extracts that are all being termed as full spectrum crude. One would likely think that while they are indeed different, that these differences would be slight and that overall they would be close enough to each other to be classified as the same thing. But, are all full spectrum extracts created equal?

To test this answer, different extraction techniques have been analyzed to determine the overall efficiency of the extraction method, as well as which plant compounds were most readily extracted using each given method. The methods that were used in this comparative analysis included: maceration (soaking plant material in solvent) using two different solvents, methanol and ethanol; soxhlet extraction (which involves refluxing the material in the extraction solvent) using methanol, ultrasonic assisted extraction (adding ultrasonic sound waves to extraction solvent) using methanol, and supercritical CO₂ extraction using two sets of parameters, 100 bar and 40^o C, as well as 100 bar and 60^o C. These extractions methods were chosen because they are either commonly used, have high reported extraction yields, or both. This selection of methods allowed for testing of a few different factors including: extraction method, extraction solvent, and extraction parameters. 

All extraction methods were performed using the same cannabis strain from the same source for extraction. All of the extracts were analyzed to determine their efficiency in extracting a variety of cannabinoids as well as the ratio of the cannabinoids found in the extract of each method. In addition to being analyzed for cannabinoid content, the extracts were also analyzed for total plant phenols as well as for total antioxidative properties. Unsurprisingly, the results showed that not all “full spectrum” CBD extracts are as full spectrum as others. In all of the extracts obtained from the different extraction methods, there were wide variances in extraction yields, cannabinoid contents, antioxidative properties, and plant phenol counts.

When it came to overall extraction yields, the CO₂  supercritical extractions were the lowest yielding extraction methods with decreasing yields occurring with increasing temperatures. In the comparison of the extraction methods all using methanol as a solvent (maceration, soxhlet, and ultrasonic assisted), the soxhlet extraction had the highest overall yield of all samples, followed by maceration and ultrasonic assisted. The ethanol maceration extraction yielded less than the methanol maceration extraction. 

In addition to the differences in extraction yields, there were also significant differences in the ratio of cannabinoids extracted as well as total phenol and antioxidative properties. The CO₂ extractions yielded large amounts of CBDA with very little CBD. The ratio of CBDA to CBD in the CO₂ extractions was roughly 5 to 1, with approximately 5 times as much CBDA as CBD. Similarly, the maceration extraction using ethanol as well as the methanol ultrasonic assisted extraction also had a higher ratio of CBDA to CBD, however, these sample ratios were much closer at around 2 to 1 CBDA to CBD. Conversely, the methanol maceration extraction as well as the soxhlet extraction both gave higher yields of CBD than CBDA. The soxhlet extraction yielded a nearly 1:1 ratio, having only a small amount more of the CBD than CBDA. While the methanol maceration extraction gave just over a 2:1 ratio of CBD to CBDA. Of note here is that the overall amount of total potential CBD in each sample remained relatively close, with all samples except the ethanol extraction being within 10% total CBD of each other. 

The ratios of CBDA and CBD were not the only differences in the cannabinoid extraction efficiencies of the different methods used however. While the ethanol extraction had the lowest amount of total CBD content extracted, it also had the highest amount of total THC extracted, as well as the highest amount of CBGA extracted. Conversely, the maceration with methanol extraction led to the highest amount of CBC  extracted. In an interesting comparison, the supercritical fluid extraction (SFE) at 40^o C led to very good extraction of CBC, while the SFE at 60^o led to very little CBC being extracted. Showing that the increase of temperature actually decreased the amount of CBC pulled from the plant matter. 

There were also differences in the total plant phenols as well as total antioxidant activity of the different extracts that had very clear trends. In the methanol extractions, going from maceration, to soxhlet, to ultrasonic assisted, there was an increase in both plant phenols and antioxidant activity. Also in the maceration extractions, going from methanol to ethanol resulted in increases of both total plant phenols and antioxidant activity. The CO₂ extractions had considerably less extracted plant phenols as well as significantly less antioxidant activity when compared to the other extraction methods. In the CO₂ extractions, the amount of plant phenols and antioxidant activity both decreased with the increase in temperature. 

So why are there such big differences in the various extracts of the same plant? And perhaps more importantly, what does that mean for consumers? The first question, while being nuanced, is still much easier to answer than the second. In trying to answer the first question it is important to get into a basic chemistry discussion about extraction. I’ll do my best to not bore you. At the core of extraction chemistry is the fact that “likes dissolve likes”. Solvents that have similar properties to the compounds being extracted will do a better job of extracting them than solvents with different properties. 

Cannabinoids are large compounds that are mostly made up of carbons and hydrogens, with a few oxygen atoms to make it interesting. When carbons are attached to other carbons or hydrogens, the bonds made are nonpolar. This means that the electrons in the bond are shared evenly between the atoms and spend roughly the same amount of time around each atom. When carbons are attached to oxygen atoms however, they make a polar bond where the electrons in the bond are more attracted to the oxygen, and therefore spend more time around the oxygen atom than the carbon atom. This makes what is called a polar bond where the oxygen atom feels the electrons more while the carbon feels them less. This means that overall cannabinoids are mostly made of nonpolar bonds, but have a few places on them that have polar bonds. 

In looking at the different solvents used, methanol, ethanol and carbon dioxide, there are different amounts of polarity in these solvents. Carbon dioxide has polar bonds, however they cancel each other out, and overall carbon dioxide is nonpolar. Methanol and ethanol are similar to each other, with the difference being that ethanol has an extra carbon and two extra hydrogens. This makes methanol more polar than ethanol. This is where things get tricky, as cannabinoids are making a mix of polar and nonpolar interactions, both become important. The polar interactions are less available, however they are stronger interactions than the nonpolar interactions. Many solvents used to extract cannabinoids thus have a mix of polar and nonpolar properties. This means that regardless of extraction method, extraction solvent will always play a key role in deciding which compounds will be extracted during the extraction process. 

As seen with the various methanol extraction methods as well as the different parameters used in the CO₂  extractions however, the parameters of the extraction also greatly influence the final product. The change in temperature, pressure, and mechanical energy added to the extraction will also affect how well each compound in the plant dissolves in the solvent being used for extraction. This was clearly evidenced by the huge change in the amount of CBC extracted in the two different CO₂ extraction parameters. While the number of parameters that affect cannabinoid extractions is complicated, it also creates a lot of room for fine tuning extractions by extractors. 

So getting back to the second question of what this means to consumers, it’s hard to say. Maybe everything, maybe nothing. There are many factors that play a part in which products become popular and which don’t. While there is obvious value in being able to design extractions that extract oils with specific compounds in mind, there is a question of economic feasibility at play. While consumers may ultimately desire tailored products to fit their therapeutic needs, advances in cannabinoid conversions and isolations will likely prove to be a more economical approach to arriving at these tailored final products. In actuality, it is product manufacturers that stand the most to benefit from understanding the differences between this full spectrum CBD extract and that full spectrum CBD extract. As most consumers typically purchase final products such as edibles or tinctures rather than CBD extracts, it is on the product manufacturers to understand the value in sourcing higher quality CBD extracts as product ingredients.

What consumers can take from this however, is that there are important compounds beyond just the CBD content in these products. Also, that they should be aware that those secondary compounds may alter the effect they feel from one CBD product to another, even one with the same amount of CBD. This knowledge will help consumers determine which products best fit their therapeutic needs. Consumers can often ask the retailers or product manufacturers what source of CBD oil they use. Having this information can help consumers in the future when choosing products that are different from the ones that they have had experience with, helping make it more likely that they will also enjoy the new product. 

Reference:

Rožanc, Jan, et al. “Different Cannabis sativa Extraction Methods Result in Different Biological Activities against a Colon Cancer Cell Line and Healthy Colon Cells.” Plants 10.3 (2021): 566.