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Now that we have discussed calibration lines, we now need to discuss how to measure their quality, that is, we need to study calibration metrics. We will discuss variance and how it is measured. Then, using illustrations and equations we will see how to calculate the standard deviation of a data set, which will give us a measure of accuracy; how to calculate the correlation coefficient, which was introduced in the last column; and the F for Regression, a measure of a thing called the robustness of a calibration, which is an obscure but important measure of calibration quality.

Hold on to your hats. To understand calibration metrics, we must talk about statistics. I will try to make this as painless as possible, using words and figures in addition to equations to explain things.

The mathematical concept of variance is also known as scatter or dispersion. In a set of data, variance is a measure of how the data are distributed with respect to the average of data. This is illustrated in 

In Figure 1, the black dots represent data points, and the X represents the average of the data set. To put this all in concrete terms I will use the isopropanol (IPA) in water infrared spectroscopy calibration line example from last time (1). The peaks used in the peak area calculations are shown in 

, the standard concentration and peak area data are in 

Note in Table 1 that the %IPA concentrations vary from 9% to 70%, this is an example of variance. The average of the %IPA values in Table 1 is 37%, this would be the X at the center of Figure 1. This variation in IPA concentrations listed in Table 1 is intentional: we varied the standard concentrations to obtain a concentration range that brackets those of the expected unknowns, a principle discussed before (2). Unintentional variance comes from random and systematic error, which we have also discussed (3). Imagine the data points in Figure 1 are the predicted values obtained by applying the calibration seen in Figure 3 to the spectra in Figure 2. Thus, in our example the total variance is equal to the sum of the variance from using standards with different concentrations AND from the error. Both these sources contribute to the variance seen in Figure 1. How do we go about quantifying this variance? Well, keep reading.

Note that the outer circle in Figure 1 is labeled “total variance” and is obtained by simply drawing a circle that includes all the data points as shown. To measure the distance, that is, variance from any given data point i to the average, we can simply subtract their values as seen in 

 is the value of data point I; and Y is the average of all data points.

The total variance then would be the sum of all variances for all the data points as given by 

Now the tricky bit here is some of the variances will have positive values, and some negative values, and when the sum is calculated they will cancel, not giving the true size of the variance. That is why rather than using Equation 2 to measure the total variance, we square each individual variance so all the values are positive, then add these numbers together as seen in 

where SST is the sum of squares total, the total variance; Σ

 is the actual value of data point I; and Y is the average of all data points.

Now given the outer circle seen in Figure 1 spans the total variance, the SST is the calculated total variance, is the area of this circle. Hence in Figure 1 it says “SST, Total Variance, Outer Circle”.

Now, no model will predict all standard concentrations with 100% accuracy because of random and systematic error. In other words, for the calibration line seen in Figure 3 the line will never pass through the center of all the data points, although this calibration line is close to that ideal. This means calibration models can model some variance but not all of it. How then do we measure the variance accounted for by a model? That would be seen in 

where SSR is the sum of squares explained by regression (the variance modeled); Y’ is the predicted value; and Y is the average value.

The term SSR is annoying, but is what is used in the literature. It is simply the variance accounted for by a model, but the “regression” thing is assuming we are using a regression algorithm, which in this case we are: linear regression.

In our example, each Y’ would be a predicted %IPA value as determined by applying the equation for the calibration line seen in Figure 3 to the peak area data seen in Table 1. Each (Y’ – Y) is the difference between each predicted value and the average, then everything is squared to get all positive numbers, and all this is added together. In terms of the diagram in Figure 1, the SSR is the area of the inner circle, hence it says, “Variance Modeled, SSR, Inner circle.” This makes sense because the SSR is based on the difference between the predicted values, the variance accounted for by the model, and the average.

What we have left to calculate is the variance not accounted for by the model. In other words, the magnitude of the total error in the model predictions. For the calibration line in Figure 3 this would be the space between the known %IPA standard values and the average. How do we calculate this? 

where SSE is the sum of squares due to error (variance not modeled); Y

 is the actual value; and Y’ is the predicted value.

The SSE, the sum of squares due to error, quantifies the variance not modeled, and is the sum of the squares of the difference between the predicted and actual values. For our IPA example, Yi would be the known IPA%, and Y’ would be the predicted % IPA for each sample. The SSE corresponds to the area of the torus in Figure 1, where it says “Unmodeled variance, SSE, torus”.

Equations 3-5 are known as the “sums of squares” equations because in each case a quantity is calculated, it is squared, and then summed. To summarize, the SST is the sum of squares total, measures the total variance, and depends upon the actual values and their average. The SSR is the sum of squares accounted for by regression, measures the amount of variance accounted for by a calibration model, and depends upon the predicted values and the average. Lastly, the SSE is the sum of squares due to error, and depends on the actual and predicted values.

Now we come to the reason why we slogged through all the math and statistics above, to be able to derive equations that tell us the quality of calibrations obtained with analytical instruments. The standard deviation, σ, is something we have discussed in the past (4). My way of explaining is that it is the average error per data point in a data set. In our %IPA example it would be the average error between the known and predicted %IPA values. If you look at the SSE equation (Equation 5) above, note that it also depends upon the known values, Y

, and the predicted values Y’. So, can we use SSE to calculate the standard deviation? Yes, we can as given by 

where σ is the standard deviation; SSE is the sum of squares due to error; and n is the number of data points.

If our data points are in units of %IPA, the SSE is in units of (%IPA)

, hence the need to take the square root of the term on the right-hand side in Equation 6. The number of data points, n, in terms of analytical instrument calibrations, is the number of standards used. For our IPA example, it is 5 as taken from the data in Table 1. Equation 6 is consistent with other equations I have presented to calculate the standard deviation as it has the total error in the numerator and the number of samples in the denominator.

The correlation coefficient, R, was mentioned in the last column (1). If you look closely at Figure 1 the big circle represents SST, the inner circle SSR, and the torus SSE. Visually, you can see that the area of the big circle is equal to the area of the inner circle and the torus. In other words, the total variance equals the sum of the variance modeled and the variance not modeled (due to error) as expressed in 

where SST is the sum of squares total, the total variance; SSR is the sum of squares due to regression, the variance modeled; and SSE is the sum of squares due to error, the variance not modeled.

Recall (1) that the correlation coefficient is on a 0 to 1 scale, where 1 means a perfect correlation between actual and predicted values, and 0 means there is no correlation. Note that I said R depends upon actual and predicted values, well so does the SSE seen in Equation 5, thus we can write how R is calculated in 

where R is the correlation coefficient; SSR is the sum of squares due to regression (variance modeled); and SST is the sum of squares total (total variance).

Note that in Equation 8, R is calculated as a ratio. What R really represents is the fraction of variance accounted for by a model. If SSR = SST there is no error, and we get R = 1. If none of the variance is modeled SSR = 0 and R = 0. Thus, we now know why R is on 0 to 1 scale.

A final calibration metric that is useful to calculate is the F for Regression (5). It is given by 

where F is the F for regression; SSR is the sum of squares due to regression; SSE is the sum of squares due to error; n is the number of data points (number of samples); and m is the number of independent variables.

The first term in Equation 9, SSR/SSE, is the ratio of the variance modeled to the variance unmodeled, that is the error. This is a lot like a signal to noise ratio, which we have talked about before (3). The greater the variance modeled compared to the variance unmodeled, the better the model. The variable m is 1 for our %IPA example.

The F for regression is a measure of the robustness of a calibration, which is a measure of how strongly the model responds to changes in the input values. In the real world a robust stance is when you are standing on two feet, a small poke will not topple you over. A non-robust stance would be standing on one foot, and the same small poke may be enough to topple you over. Similarly, calibrations may be accurate but not robust because a small change in conditions can have a huge effect on the results. Therefore, robust calibrations are always preferred, sometimes even at the expense of accuracy.

Variance is a measure of the spread or scatter in the data, and for calibrations the total variance equals the variance modeled plus the variance unmodeled. The three sums of squares equations measure the total variance, SST, the variance modeled, SSR, and the error, SSE. The calibration metrics of the standard deviation, correlation coefficient, and F for regression can be calculated from these quantities.

Smith, B., Calibration Science, Part III: Calibration Lines and Correlation Coefficients, Cannabis Science and Technology, 2024, 7 (2), 6-11.

Smith, B., Quantitative Spectroscopy: Practicalities and Pitfalls, Part I, Cannabis Science and Technology, 2022, 5 (5), 8-13.

Smith, B., Calibration Science, Part II: Systematic Error, Signal-to-Noise Ratios, and How to Reduce Random Error, Cannabis Science and Technology, 2024, 7 (1), 8-11.

Smith, B., Statistics for Cannabis Analysis, Part I: Standard Deviation and Its Relationship to Accuracy and Precision, Cannabis Science and Technology, 2021, 4 (8), 8-13.

Brian C. Smith, Quantitative Spectroscopy: Theory and Practice, 2002.

, PhD, is Founder, CEO, and Chief Technical Officer of Big Sur Scientific. He is the inventor of the BSS series of patented mid-infrared based cannabis analyzers. Dr. Smith has done pioneering research and published numerous peer-reviewed papers on the application of mid-infrared spectroscopy to cannabis analysis, and sits on the editorial board of 

. He has worked as a laboratory director for a cannabis extractor, as an analytical chemist for Waters Associates and PerkinElmer, and as an analytical instrument salesperson. He has more than 30 years of experience in chemical analysis and has written three books on the subject. Dr. Smith earned his PhD on physical chemistry from Dartmouth College. Direct correspondence to: 

Smith, B., Calibration Science, Part IV: Calibration Metrics, 

Cannabis Analysis 

Here, we discuss the importance of calibration metrics and how to measure calibration quality.

Calibration Science, Part IV: Calibration Metrics

At one point in time, it was easy to make the statement that CBD comes from hemp and THC comes from cannabis. However, these parallel industries have been developing rapidly and the dividing lines have blurred. Products like “hemp-derived” THC gummies or high-CBN tinctures can be found in both hemp and cannabis marketplaces. This article will cover what the differences are between hemp and cannabis, the products that are on the market today, and why it is important to know where your product is coming from.

In the realm of cannabis science, understanding the distinctions between cannabinoids derived from hemp and those from cannabis is crucial. While both plants belong to the 

 species, they exhibit significant differences in their chemical compositions and legal classifications. Moreover, the availability of hemp-derived tetrahydrocannabinol (THC) products online adds another layer of complexity to the conversation. Let’s delve into the nuances of these cannabinoids and unravel why hemp-derived THC products have become increasingly accessible.

Cannabinoids are a class of chemical compounds found in cannabis plants, including both hemp and cannabis. These compounds interact with the body’s endocannabinoid system, influencing various physiological processes, such as mood, memory, appetite, and pain sensation. Among the hundreds of cannabinoids identified, THC and cannabidiol (CBD) are the most well-known and studied.

Hemp vs. Cannabis: Understanding the Contrast

Hemp and cannabis share the same genus and species, but they differ significantly in their cannabinoid profiles and uses. Historically, hemp has been cultivated primarily for industrial purposes, such as textiles, paper, food, and wellness products. It contains high levels of CBD and low levels of THC, typically below 0.3% THC content by dry weight, as mandated by law in many jurisdictions.

On the other hand, cannabis, commonly referred to as marijuana, contains higher levels of THC. THC is the cannabinoid responsible for the “high” associated with cannabis consumption, along with varying levels of CBD and other “minor” cannabinoids. Cannabis strains can have THC concentrations ranging from a few percent to over 20%, depending on the cultivar.

Hemp-Derived THC Products: Legal and Regulatory Framework

The legality of THC products, whether derived from hemp or cannabis, hinges on the concentration of THC and the specific regulations governing their production and distribution. In many jurisdictions, hemp-derived products with less than 0.3% THC are considered legal, while cannabis-derived products may be subject to stricter regulations or outright prohibition.

The emergence of hemp-derived THC products online can be attributed to the Farm Bill of 2018 in the United States, which legalized the cultivation and commercialization of hemp and hemp-derived products with low THC content. This legislation opened doors for the production of a wide range of hemp-derived CBD and THC products, including oils, tinctures, edibles,
and topicals.

However, it’s essential to note that regulations surrounding hemp-derived THC products vary globally. These hemp-derived products that contain Delta-9 or Delta-8 THC are produced through chemical synthesis, which converts CBD into THC. While they are hemp-derived, the hemp market is far less regulated and quality controlled than the regulated cannabis markets. This could result in less safe hemp-derived THC products available to the market, but more profitable for hemp-derived THC businesses as there are tax benefits and fewer regulatory boundaries. The accessibility of these intoxicating hemp products is concerning to regulatory agencies and the regulated cannabis industry.

While hemp is renowned for its high CBD content and has expanded offerings to include hemp-derived THC products, it also contains a plethora of other cannabinoids with potential therapeutic benefits. Some of the cannabinoids that can be derived from hemp include:

: CBD is the most abundant cannabinoid in hemp and is known for its potential therapeutic properties, including anti-inflammatory, analgesic, anxiolytic, and neuroprotective effects. It has gained popularity for its purported role in alleviating various health conditions, such as anxiety, chronic pain, epilepsy,
and insomnia.

: CBG is considered a precursor to other cannabinoids, including THC and CBD. Although present in low concentrations in most cannabis strains, hemp cultivars bred for high CBG content are now available. Preliminary research suggests that CBG may have potential anti-inflammatory, neuroprotective, and appetite-stimulating effects.

: CBN is a degradation product of THC, formed as THC oxidizes over time. While typically found in trace amounts in fresh cannabis, aged or heated cannabis products may contain higher levels of CBN. Some studies suggest that CBN may have sedative effects and could potentially aid in sleep disorders.

: CBC is another non-intoxicating cannabinoid found in hemp and cannabis. Research indicates that CBC may exhibit anti-inflammatory, antidepressant, and analgesic properties. It also shows potential in promoting neurogenesis, the formation of new neurons in the brain.

: THCA is the precursor to THC and is found in raw, unheated cannabis plants. When exposed to heat through decarboxylation, THCA converts to THC, the psychoactive compound responsible for the euphoric effects of cannabis.

In addition to these cannabinoids, hemp also contains trace amounts of other minor cannabinoids, terpenes, flavonoids, and phytonutrients, which collectively contribute to the entourage effect—the synergistic interaction of various cannabis compounds that may enhance therapeutic outcomes.

Minor cannabinoids are produced on the hemp market as isolates and supplied by a number of reputable manufacturers. Quality assurance and supplier vetting is an important step in formulating hemp-derived products. Access to a supply of minor cannabinoid isolates has facilitated a burst of product innovation on the hemp market. The market has become hyper-competitive and an opportunity for consumers to gain access to a wide variety of product types and cannabinoid ratios.

Understanding the differences between cannabinoids derived from hemp and cannabis is paramount for consumers, healthcare professionals, and policymakers alike. While hemp-derived THC products offer a legal alternative for those seeking the potential therapeutic benefits of cannabinoids, it’s essential to navigate this rapidly evolving landscape with caution and awareness of regulatory frameworks.

As research into cannabinoids continues to expand, we can anticipate further insights into their mechanisms of action, therapeutic potential, and optimal applications. In the meantime, exploring the diverse array of cannabinoids derived from hemp underscores the multifaceted nature of cannabis science and its profound implications for health and wellness.

 is the founder, CEO, and Chief Extractor of Heylo. With a background in chemistry and clinical research, Lo was inspired to explore cannabis as a medicine and to enter the emerging industry. She joined Eden Labs, a leading CO

 extraction equipment manufacturer to support and expand a Research and Development department. There she managed the development of their latest and greatest CO

extraction system. In 2017, after working with Eden Labs and another cannabis processor, Lo launched Heylo with a mission to help people get more out of life with cannabis.

Friesen, L., Decoding Cannabinoids: Exploring the Differences Between Hemp and Cannabis, 

Extraction Science

This article will cover what the differences are between hemp and cannabis, the products that are on the market today, and why it is important to know where your product is coming from.

Decoding Cannabinoids: Exploring the Differences Between Hemp and Cannabis

Sweeping and dismantling numerous cannabis crops throughout the cultivation space, you need to look no further than at the plant disease called hop latent virus (HLVd). Also known as Dudding Disease, the virus needs in order to survive and reproduce, a compatible host which it has done in several other plant species but has now made its entrance into cannabis cultivation.

In continuation of our cultivation education series, Adam Jacques, a world-renowned expert with more than 20 years’ experience cultivating various unique strains of cannabis, as well as the Chief Geneticist at AgSense LLC, and Zacariah L. Hildenbrand, a research Professor at the University of Texas at El Paso, the principal founder of Inform Environmental, a partner of Medusa Analytical, and is a director of the Curtis Mathes Corporation, get to the root of the issue of experiencing an HLVd infestation and if anything can be done to salvage your crops.

Can you tell us about the Hop Latent Viroid (HLVd) virus and how have you seen it affect cannabis crops?

: These kinds of viruses started, we started noticing with this probably 15 years ago, right? And it got called everything tomato mosaic, hemp mosaic, you know, all of these, and everybody was considering it. Well, this must be a mosaic virus of some sort of tobacco mosaic, maybe. What we started seeing was what we call Dudding, the production of plant material wasn't great. You would see lower numbers, reduced yield, and would get worse over time. And so, you know, everybody was trying to come up with, 'well, what is this?' Obviously, now, we know it's HLVd, right? So once that got figured out, really, it was just, at that point, figuring out what are the metrics of damage that it's doing to the crops? It's not like hemp mosaic virus isn't a thing. It's a thing that exists and it expresses itself roughly in the same way. So, when we start talking about hop latent virus, we do to really know what you have, you're gonna need a lab test on it. I would say that, as of right now, I would be surprised if any number less than 50% of clones—and it's in this country—didn't have it.

: It's ubiquitous. From what I see, right, with so much of this poly hybrid desertion, with all these genetics, just being mixed and mingled together, there really hasn't been much concern for 'Are there any, is there any kind of genetic baggage associated with doing this', right? It's just like, 'Hey, this genetic was fire and this other genetic is fire, and I'm gonna put fire and fire together and it's gonna be 10 times better' and there's just no consideration for the genetic lineage and, and you can be stuck with hop latent viroid. The issue with this too, is you can have plants that appear asymptomatic for quite some time, and yet they're still carrying the virus. They're almost like a vector, if you will, and then boom, you then introduce that with another genetic. Based on the genetic background, maybe then the virus expresses into its actual phenotype and condition. And then you got a real problem. I think the folks at Medicinal Genomics probably have the best handle on this. They published a bunch of papers on this looking at hop latent viroid's prevalence across various genetics. And I mean, to Adam's point, it's well over 50%. I mean, it's everywhere. I think one of the questions I asked him is if you could detect this in the seeds? Or if or how long do you have to wait until this starts being detectable in the plant? And they were still working on that. But it's a ubiquitous issue with varying effects on client's outcome, and it still remains to be determined how to completely eradicate it.

: A lot of ways to do this in this industry is observational. It's not like I'm going to every plant and doing a test on it every day to see if it has a virus or an issue. A lot of the things that I'm doing is with my eyeballs. So, if I have spider mites or russet mites, or something like that, I can visualize it. This is, it hides in the plant itself. So, it's not really expressing a lot of things that would cause me concern, especially in the vegetative state. I mean, you do things like stunted growth, reduced vigor, brittle stems, you know, less flower mass, those things happen. But in a newly planted clone and fresh soil who's real healthy, it may be using that energy fighting that virus, but it's in such a healthy state at this point that you're not really seeing any of the side effects. So, when you flip it into flower, and you start going and you're adding stress to the plant into a flowering cycle, and trying to push weights and things like that, that's when you really see the energy of the plant, focusing from production of the plant into fighting the virus in the plant. That's where you really start to see a lot of the side effects coming out at that point. It's too late, right? You've already wasted six weeks. Everything is stunted. Another awesome thing about this disease is that let's say you grow in aeroponics. Well then, your entire water supply and all of your lines are infected now because it will transfer through the roots. So, it hides by not being a big problem until it is.

: It's a really good virus. Good viruses are one that really don't perturb their hosts much and their whole goal is just to spread its DNA. A really bad virus is one that's lethal, kills its host before it can spread on, but this one's actually quite effective in that it spreads so readily without having a significant impact on the host until it does. I've always seen it with the virus, that it's a really steep decline. It's like, 'Oh, there's something weird going on with this plant' and Adam's, right. You may see it initially in the veg, like, 'Ah, maybe it'll be okay here'. And then all of a sudden, it's just like, 'Wow, this looks terrible. We don't have any trichrome production, we have weird leaf morphology. Now we have discoloration, this plant is dead'. So, or it might as well be dead. You just end up sacking it anyways. So, it's definitely one of those things that if you're not on top of it, can be a major issue. And a lot of people to, kind of going back to my comment about the polyhybridism, people are so eager to get genetics from other folks. We've discussed about, you know, the prevalence of mites and bugs and pathogens, and but what about the prevalence of viruses that you're passing back and forth? You know, I think people need to be more cognizant of the provenance of the genetics that they're getting, before they get super excited about the new hype strain out of someone's garage.

Why should cultivators and consumers be concerned of HLVd?

: Consumers don't need to be. It's an issue with the cultivators. It is bad for the cultivators, you're looking at a 10 to 15% loss in cannabinoids, you're looking at a 30% loss and weight off of the plants. You're looking at a much lower quality flower. So, something that may have been top shelf money, you're now getting B or C grade money for less and you're getting less and the THC percentage sucks. Stuff duds out. It's just terrible. It's gross, right? So, it turns good flower into [unusable] flower. On the consumer side, you know, I don't think we'll ever see a financial hit to them on it being that the industry is what it is right now. I don't think smoking something that had hop latent viroid is going to do anything to you. But, if you are getting cannabis from like let's say your grower or your caregiver or something that it is this, you're getting a much lower quality product than you should be getting. So, I guess you're damaged a bit in that way.

: Yeah, I don't think the virus can transform from plant kingdom to eukaryotic animals. I don't think that's the thing. But to Adam's point, it's just it's going to result in a diminished product, it's going to be less efficacious. And so obviously is not going to be the same medicinal value, as if you had an uncontaminated sample.

: And as a grower, those things that I mentioned, that is your margin, right? You'll go bankrupt if you have it and don't deal with it.

What can be done to prevent or contain the effects?

: So before I bring anything into my room, I would prefer to get a test on getting hop latent tests and getting tests isn't difficult, like I have to go to the university now to get something like that. You can actually buy testing kits online to test your plants for hop latent. Before you bring anything into your room, or if you're starting from seed or something new like that, it probably would behoove you to test for viruses in your plants. If they do have viruses in your plants, it's not a death sentence for the plant necessarily, right? We can fix this. But it's tough. Honestly, it's tough not to bring this into your space right now.

: Yeah, it's just so ubiquitous. So, I think really, it just goes back to having a strong understanding of the reliability of the source of your genetics. I think that's your best course of action, getting it from people that take care of their plants, sterilize things that they can, and just run a clean operation. I think the worst mistake you can make is just haphazardly taking a clone from some bro that you met, and you just have no idea what sort of conditions they were dealing with there and then boom, you could have systemic termination of your entire facility.

Are there any other cannabis pathogens to be worried about? (Fusarium, Pythium, etc.)?

: Mosaic viruses, I would keep an eye on, they can do damage and the damage looks a lot like this. So, it's roughly the same. That's the one everybody was looking out for. For a long time. Specifically, tobacco, hemp, and tomato mosaic viruses. As far as viruses go, that's about, you know, those are the worries that that I have.

, even powdery mildews. That's tough because that's systemic? 

 will kill you so it’s a good one to worry about.

Is there any products you use/recommend to detect or use to deal with an HLVd infestation?

: Yeah, I would just say again, it just goes back to the analytical techniques, [polymerase chain reaction] PCR. I think it's becoming so readily available, that you could have kind of at home kind of garage enthusiast, if you will, running their own PCR as a supplement to their grow. And it's been nice. I mean, we've seen the entire industry, like the folks at Shimadzu or the folks at Agilent. They're trying to take their cannabinoid analysis and their terpene analysis and make it kind of miniaturized so that the at-home user, maybe it's more accessible, and that the instruments are becoming cheaper. I think in five years' time, if you're a commercial outfit, you're going to have your own [high-performance liquid chromatography] HPLC to do cannabinoids, you'll have your own [gas chromatography mass spectrometry] GC-MS, to do terpenes, and you'll have your own PCR to do virus testing. And that's just going to be part of your daily protocol.

: I would say as far as products go to deal with this, no. There's not something you can water in or spray on the plant that's going to save it. If you have a virus in real life, same idea, right? You need to find something that's a directed cure for that thing, which just doesn't exist yet for this. You can make your plants healthier, which is going to help mitigate the damage that this virus is doing. But then you're just putting cost on top of costs to try and keep a sick plant alive. But no, there's no answer to fixing it in a product or a bottle that you can buy.

If you know somebody who's really good at tissue culture, you could go in and do a sanitizing tissue culture on it and that has been proven to remove the virus from plants. So, if there's a plant that you really want to keep in your stable, you can put out the financial needs to get something tissue cultured and completely cleansed like that. It does work, I’ve seen it. It's a lot to do for, let's say, 500 plants in a grow. Let's say it's some killer genetic that's unique to you, and you want to keep it and it has an illness, there are ways to remedy this. But the plant doesn't like it. Plants don't like getting bleached necessarily. And I would, there's certain genetics that if that issue came up with them, I would find a way to save them. I would go that far to save those genetics. But I would say, for the average home grower at home, if all of a sudden you figure out that's what's happening, just rip it out and start again. Getting your plant tissue cultured and cleaned, like that's going to cost more than grow in that plant’s worth.

: If anyone experiences this for the first time, just start over. Don't try to play Sherlock Holmes to figure out where it came from and how to solve it. Just start over with new stuff and hopefully go back to the basics.

: I think clone sharing in general is as old as growing this plant is. It's like baseball cards amongst each other. Right? Who's got the new, unique elite thing? When me and Christian West started out, that was the thing, right? You would go and you go around, you collect all the clones from the different areas and that's how you got genetics. Now, I don't think my number 50% + is wrong of clones out there, have this. Generally, you're not going to see this expressing itself in a clone. So, you have no way of knowing with clone sharing whether you're getting a clean clone or not. Could there be systems put into place to make that easier, like maybe a certificate of testing on it or something, but then all of a sudden that clone’s cost is not $20 anymore. It's hundreds of dollars to get a clean clone. I can't fault people for sharing clone and seed. That's a tough thing to do and it's exciting thing to do. And then you get new things. Turns out that can come with a lot of issues.

Colli, M. HLVd: The Menace to Cannabis Crops, 

The Cultivation Classroom

In continuation of our cultivation education series, Adam Jacques and Zacariah L. Hildenbrand, get to the root of the issue of experiencing an HLVd infestation and if anything can be done to salvage your crops.

HLVd: The Menace to Cannabis Crops

In this month’s column, guest contributor, Rob Thomas takes a critical look at the big four heavy metals which are regulated by the vast majority of US states and suggests that there is compelling evidence in the public domain that the panel should be increased because there is not a good understanding of sources of elemental contaminants in the production of cannabis consumer products. As a result of the inadequate nature of these state-based regulations, consumer safety is most likely being compromised.

Part 1 of this column examines the fractured nature of state-based regulations and compares it with the federal limits for pharmaceutical products and dietary supplements. Part 2 will look at specific examples in the public domain of elemental contamination of cannabis consumer products, which shows that other elements are worthy of consideration and should be an integral part of the regulatory framework.

Even though cannabis is in the process of being rescheduled from a Schedule I to a Schedule III drug by the Drug Enforcement Administration (DEA), uncertainty about federal oversight of cannabis consumer products in the US has left individual states to regulate its use. Cannabis is legal for medicinal purposes in 39 jurisdictions, while 19 states and Washington, D.C. allow its use for adult recreational consumption (1). However, the cannabis plant is known to be a hyper-accumulator of toxic metals in the grow medium and other manufacturing pathways, so it is critical to monitor levels of elemental contaminants to ensure cannabis products are safe to use. Unfortunately, there are many inconsistencies with heavy metal limits in different states where cannabis is legal. The vast majority of these states set limits for the “big four” heavy metals: lead (Pb), arsenic (As), cadmium (Cd), and mercury (Hg). New York State also requires the testing for chromium (Cr), nickel (Ni), copper (Cu), and antimony (Sb), while Michigan requires inorganic As (not total) and also adds Cr, Ni, and Cu to the big four. Maryland and a few other states also include Cr as well as the big four. Some states base their limits directly in the cannabis, while others are related to human consumption per day. Some take into consideration the body weight of the consumer, while other states do not even have heavy metal limits. To complicate the situation, certain states only require heavy metals in the cannabis plant/flower, while some give different limits for the delivery method such as oral, inhalation, or transdermal (2). This review article will provide evidence from publicly-available sources that a wider panel beyond the “big four” heavy metals are worthy of consideration, suggesting that the industry does not have a good understanding of sources of elemental contaminants in the cultivation and production of cannabis consumer products and as a result the fractured nature of state-based regulations could potentially be compromising consumer health and safety.

The inconsistencies of state-based limits would make it extremely complicated to implement at the federal level, unless there was a completely fresh assessment of the regulations. For example, why does New York State currently have action limits for eight elemental contaminants whereas the vast majority of the other states only require the big four? In other words, what do New York regulators know about the toxicological impact of the four additional elements, compared to California that only regulates four? Or why does Michigan require inorganic arsenic while all other states just list total arsenic? Furthermore, how can some states justify no heavy metal action limits at all? It might all become a moot point when federal regulators eventually have oversight of the industry, but what will that regulatory panel look like? The disparity in state-based limits might not be a good indicator, but there could also be clues in the way federally approved cannabidiol (CBD) drug formulations have historically been regulated, together with an understanding of how standards and reference material organizations have approached developing standardized analytical methodology for measuring heavy metals.

To highlight the disparity between state-based limits and federal guidelines for pharmaceutical formulations, the Food and Drug Administration’s (FDA) Botanical Review Team in the Office of New Drug Products recently published a study entitled, “Quality Standards in State Programs Permitting Cannabis for Medical Uses” (3), which compared the maximum allowable limits of the big four heavy metals for states that had Medical Cannabis Programs (MCP) with 

 (USP) Chapter <232> permitted daily exposure (PDE) concentrations in inhalation and oral drug formulations routes of administration (ROA) and 

 Chapter <2232> Elemental Contaminants in Dietary Supplements (4). Although the actual states are not mentioned, it can be seen from 

 that in the majority of cases, the eight medical programs reported are very different to the 

 limits. In fact, it can be seen by much of the data in bold, that they are significantly higher than the federal limits. There is no obvious reason as to why the state programs action limits are so different, but it was interesting that the researchers’ critique was three-fold:

Testing for the four heavy metals in inhalation and oral products was lacking in the majority of state medical programs.

Even when present, it was inconsistent across the different jurisdictions.

It did not always align with USP recommendations.

So clearly there is a need for more consistency across state lines, particularly as the industry inevitably moves in the direction of federal oversight. This is further compounded by the fact that there is a great deal of evidence in the public domain that only monitoring the big four heavy metals is not enough to ensure consumer safety. But how many metals should there be in an expanded panel, particularly as there is no comprehensive understanding of the sources of elemental contaminants in the cannabinoid cultivation and production processes? Moreover, unlike drug products, there has been no risk assessment studies carried out with regard to heavy metal contaminants in cannabis consumer products and for that reason, consumer health is likely being compromised.

So, assuming that only monitoring the big four heavy metals is inadequate to ensure consumer safety, what is a realistic panel of elemental contaminants that should be used for state regulatory purposes? The only solid evidence we have at this current time for what could be a federally regulated panel is with the FDA approved CBD-based drug Epidiolex, which is available in the US to treat childhood seizures. Manufactured by UK-based GW Pharmaceuticals (now a division of Jazz Pharmaceuticals), it went through the regulatory process prior to its introduction in 2018 to get it approved in the US (5) and had to show compliance by meeting permitted daily exposure (PDE) limits for up to 24 elemental impurities as defined in 

 Chapter <232> (3) and International Council for Harmonization of Technical Requirements for Pharmaceuticals for Human Use (ICH) Q3D guidelines (6). In practice, because eight of those metals are associated with the drug synthesis process using platinum group catalysts which was not used in the Epidiolex manufacturing process, only 16 were used for manufacturing quality assurance purposes.

Furthermore, USP recently published a draft monograph for CBD as an active pharmaceutical ingredient (API) for a federally approved drug formulations which stated that (7):

“Elemental impurities in official drug products are controlled according to the principles defined and requirements specified in Elemental Impurities—Limits, Chapter <232>, as presented in the General Notices 5.60.30.”

In the long term, this could possibly indicate that the FDA will regulate CBD products for up to 24 elemental contaminants when it eventually has oversight of the cannabis industry. But more importantly, in the short term it implies that CBD being manufactured in the US for recreational or medicinal purposes does not meet the purity requirements for federally approved drugs, because currently it only has to comply with the state’s maximum limits for heavy metal contaminants, which in most US states is typically only Pb, Cd, As, and Hg.

However, it’s important to stress that a panel generated by pharmaceutical regulators isn’t necessarily one that should be used by the cannabis industry, as the process for manufacturing cannabinoids is very different to drug products. In addition, many consumer products are not intended for medicinal purposes, but can be classified as foods, beverages, candies, or snacks so perhaps an argument could be made that they should be treated more like food products than drug substances. However, based on recent reports, it is clear the FDA is not doing such a good job of keeping us safe from the effects of toxic metals in our food supply as exemplified by a reprimand from Congress in 2021 for failing to identify processed baby food cereals with elevated levels of heavy metals (8) and more recently, for not flagging a case of intentional adulteration of cinnamon with lead chromate (Pb CrO4) for economic gain (9). So, until there is a mandatory requirement for food manufacturers to test their products on supermarket shelves, there is always the potential for incidents like this. So irrespective of what regulated limits are used, at some point the cannabis industry needs to carry out a comprehensive risk assessment study of its own to provide evidence as to what metals should be monitored, similar to what regulators did to characterize elemental impurities in drug products and formulations (10). To better understand this risk assessment process and how it might have a bearing on a cannabis panel of heavy metal contaminants, let’s take a detailed look at how regulations for pharmaceutical and supplements came into existence, which eventually became the basis for state-based oversight of the cannabis industry.

The pharmaceutical industry began the process to overhaul regulations and methodology for elemental impurities over 20 years ago when it updated its 100-year-old semi-quantitative sulfide precipitation colorimetric test for lead and a small suite of heavy metals to eventually arrive at a method to monitor 24 elemental impurities in drug products using plasma spectrochemistry. Moreover, they completely reassessed the toxicological impact of these elemental contaminants based on well-established animal models and defined them by permitted daily exposure (PDE) limits according to the mode of administration (oral, parenteral, inhalation, transdermal) and classified them by toxicity and the probability of finding them in the drug manufacturing process.

These limits were described in USP <232> - Elemental Impurities (4) and ICH Q3D Guidelines (6), together with USP Chapter <2232> for dietary supplements (4). While the measurement procedures were defined in USP Chapter <233> which describes the plasma spectrochemistry methodology (inductively coupled plasma optical emission spectroscopy [ICP-OES] or inductively coupled plasma mass spectrometry [ICP-MS]), microwave digestion procedure and a full set of validation protocols (11). 

 represents the full list of USP/ICH elemental PDE limits in microgram per day (µg/day) per delivery method and toxicological classification, which are explained in greater detail in 

It’s also important to emphasize that the data in Table 2 are maximum limits per day. So, for a suggested daily dosage of 10 g, these limits should be divided by ten to calculate the maximum allowable limits in the drug products in microgram per gram (µg/g). However, even though 10 g is a typical maximum daily dosage for drugs, we have no way of knowing in what quantities consumers use cannabis products. So, if larger or smaller quantities are being used these PDE limits will be different, based on the weight consumed. Furthermore, the mode of administration will also impact the regulated limit, so inhalation PDEs in most cases are significantly lower than the oral ones. In addition, the classification number will impact the frequency of testing with Class 1 and 2A metals of higher priority than the Class 2B and 3 metals. In fact, the classification can offer clues as to what elements from this list would be worthy of inclusion in an expanded panel to regulate cannabis and hemp consumer products. For example, Class 1 and 2A would warrant inclusion in any regulated panel, whereas Class 2B metals would likely not be required at all, because they are not used in the cannabinoid manufacturing process. On the other hand, Class 3 metals may not be required for all oral products but would definitely be required for inhalation products such as vaping devices.

Part 1 was essential background information to the topic of this review article. Part 2 of the column takes a closer look at some of the evidence in the public domain, which underscores that the industry does not have a thorough understanding of heavy metal contaminants in consumer products which could support the measurement of a wider panel of elemental contaminants in cannabis materials.

Thomas, R., The Importance of Measuring Heavy Metal Contaminants in Cannabis and Hemp, Analytical Cannabis, 2021, 

https://cdn.technologynetworks.com/ac/Resources/pdf/the-importance-of-measuring-heavy-metal-contaminants-in-cannabis-and-hemp-312957.pdf

Pruyn, S.A.; Wang, Q.; Wu, C.G.; and Taylor, C.L., Quality Standards in State Programs Permitting Cannabis for Medical Uses, Cannabis and Cannabinoid Research, 2022, 

United States Pharmacopeia (USP) General Chapter <232> Elemental Impurities in Drug Products and Chapter <2232> Elemental Contaminants in Dietary Supplements, 

https://www.usp.org/chemical-medicines/elemental-impurities-updates

FDA Approves First Drug Comprised of an Active Ingredient Derived from Marijuana to Treat Rare, Severe Forms of Epilepsy, FDA News Release, 2018, 

https://www.fda.gov/news-events/press-announcements/fda-approves-first-drug-comprised-active-ingredient-derived-marijuana-treat-rare-severe-forms

ICH Guideline Q3D on Elemental Impurities (R1), European Medicine Agency 

https://www.ema.europa.eu/en/documents/scientific-guideline/international-conference-harmonisation-technical-requirements-registration-pharmaceuticals-human-use_en-32.pdf

USP Draft Monograph for CBD, Pharmacopeial Forum (PF) 48(1), January 2022, 

https://www.gmp-compliance.org/gmp-news/usp-draft-monograph-for-cbd

Thomas, R. Regulating Heavy Metals in Baby Food: The Challenges of Food Manufacturers and the FDA Being on the Same Page, AP Column, Spectroscopy Magazine, 2021, 36 (7), 10-16, 

https://www.spectroscopyonline.com/view/regulating-heavy-metals-in-baby-food-the-challenges-of-food-manufacturers-and-the-fda-being-on-the-same-page

FDA Takes Steps to Ensure Safety of Cinnamon Products Sold in the US, FDA News Release, 2024, 

https://www.fda.gov/news-events/press-announcements/fda-takes-steps-ensure-safety-cinnamon-products-sold-us

Thomas, R.; Destefano, A. Understanding Sources of Heavy Metals in Cannabis and Hemp: Benefits of a Risk Assessment Strategy, Analytical Cannabis, 

https://www.analyticalcannabis.com/articles/how-to-better-understand-sources-of-heavy-metal-contaminants-in-cannabis-part-1-what-can-we-learn-313862

United States Pharmacopeia General Chapter <233> Elemental Impurities – Procedures: Second Supplement to USP 38–NF 33, 2015, 

https://www.usp.org/chemical- medicines/elemental-impurities-updates

 is the principal scientist at Scientific Solutions, a consulting company that serves the educational needs of the trace ele­ment user community. He has worked in the field of atomic and mass spectroscopy for almost 50 years, including 24 years for a manufacturer of atomic spectroscopic instrumentation. Rob has written over 100 technical publications, including a 15-part tutorial series entitled, 

. He is also the editor and frequent contributor of the "Atomic Perspectives" column in 

 magazine, as well as serving on the editorial advisory board of 

. In addition, Rob has authored six textbooks on the fundamental principles and applications of ICP-MS. His most recent book is entitled 

A Practical Guide to ICP-MS and Other AS Techniques

, which was published in September 2023. Rob has an advanced degree in analytical chemistry from the University of Wales, UK, and is also a Fellow of the Royal Society of Chemistry (FRSC) and a Chartered Chemist (CChem).

Thomas, R. Understanding Sources of Heavy Metals in Cannabis and Hemp Consumer Products, Part I: Is the Fractured Nature of State-based Regulations Ignoring the Evidence? 

Navigating the Lab

The first part of this column examines the fractured nature of state-based regulations and compares it with the federal limits for pharmaceutical products and dietary supplements.

Understanding Sources of Heavy Metals in Cannabis and Hemp Consumer Products, Part I: Is the Fractured Nature of State-based Regulations Ignoring the Evidence?

From simple DIY to lessons learned from mainstream agriculture to chemical discoveries, extraction techniques are driving more product innovation.

The search to isolate more and more cannabinoids is driving extraction development. That’s been a trend for years (1).

But there is also a search for better methods of extraction (read: cleaner, greener) and more focus on extracting specific cannabinoids, as their value to human wellness is explored. Newer concentrate products, such as badder and cured resin—made using a solvent within a pressurized closed-loop extraction system—are showing up at dispensaries. They are among the top sellers in the California, Oregon, and Nevada markets (2).

points to the use of extraction methods such as ultrasonic-assisted, microwave-assisted, supercritical fluid, and pressurized liquid extraction processes as greener options than conventional extraction processes, because they reduce the need for synthetic and organic solvents, cut down on operational time, and produce a better-quality extract with a higher yield (3). Less solvent is used, and extraction times are reduced from conventional methods.

That’s all good for the recreational market. But the potential recent rescheduling of cannabis from Schedule I to Schedule III, announced in April 2024, will drive the search for a reproducible, pharmaceutical-quality cannabis product that will drive further innovation.

This installment of the “Tech Innovations” column will discuss new methods and lab processes to do more targeted cannabis extraction. There is also a growing need to accurately measure homogeneity in the cannabis product, especially for medicinal cannabis, and that begins in the extraction process.

Extraction technology in the cannabis industry is becoming part of the global sustainability efforts, with the goal of developing medicinal preparations from the biomass of cannabis. That biomass extraction technology is becoming standard operating procedure for mainstream cash crops, with interesting product payoffs. But the road to getting there in the cannabis industry is full of obstacles.

The amount of research into cannabis waste is extremely small relative to the research into cannabis itself, in part because of the need to control that biomass from getting into the black market. Cannabis biomass has to be destroyed or otherwise disposed of (landfill, composting, anaerobic digestion) instead of recovered as a resource (4).

Waste valorization (5) has been a research interest of Josh Katz, senior research and development scientist at Trulieve (6). “We grow all of this biomass,” Katz explained. “We reduce the volume of the mass by a certain amount, but it's still a gigantic amount of biomass that we either have to throw away or compost or whatever. There's a lot of interesting chemistry out there that can take this spent material and digest it into commercially interesting products that the cannabis industry hasn't even thought of.”

The biomass of cannabis are the so-called non-utilized components of the plant, such as the roots, which can be rich in polyphenols, and other bio-active compounds, which can be used for health promoting products.

To get an idea of what can be created through extraction of biomass, the cannabis industry should take note of how it works for some mainstream cash crops.

The annual yield of banana peels is 60 million tons; orange peels 10 million tons; avocado pits and peels 4 million tons; and wine by-products more than 14.6 million tons, according to researchers (7).

PeelPioneers, in the Netherlands processes citrus peels into oil, D-limonene. Garden of Natural Solution Co., Ltd. uses an ultrasonic extraction method to produce citrus peel extract with antioxidant effects as a cosmetic ingredient (8). Lianyuan Kangbiotech Co., Ltd. extracts various fruits and fruit peels to obtain sweetener, oils, and polyphenols (9).

Keracol, a company formed by the University of Leeds (10), extracts resveratrol, a natural molecule found in the outer skins of red grapes, which is an antioxidant and known to have protective anti-ageing properties.

Biomass extraction progress is coming to cannabis. There is an extraction method for working with biomass that comes from Milestone on their Ethos platform (11). “It doesn’t even extract cannabinoids,” Katz said. “It’s a terpene extractor. It allows you to take flower immediately after harvest, extract the terpenes out of it, dry the biomass out, re-extract the cannabinoids and you can basically make a vape cart out of the biomass of flower that was harvested yesterday.” They have used it in a couple of their products so far, he said. “From a dollars and cents point of view, it's a substantially cheaper route to cannabis-derived terpenes than CO2 extraction is. Throughputs are comparable, and the total terpene content in what comes out is higher than CO2 extraction. It uses a pretty interesting strategy for getting the terpenes out of material that is not unique to cannabis by any stretch of the imagination.”

Aside from biomass, another extraction method in the sustainable camp is pressurized liquid extraction (PLE) (12), a high-throughput and green extraction technique for the sustainable extraction of bioactive compounds from natural sources.

PLE—also called accelerated solvent extraction (ASE), pressurized fluid extraction (PFE), pressurized hot solvent extraction (PHSE), high-pressure solvent extraction (HPSE), high-pressure high-temperature solvent extraction (HPHTSE), and subcritical solvent extraction (SSE) (13)—is one method of extraction that is easy to use and efficient, using elevated temperatures and moderate to high pressures.

PLE works with a reduced amount of solvent, with the ability to extract a wide range of compounds—ideal for a plant like cannabis where there are more than 550 chemical compounds in cannabis, with more than 100 phytocannabinoids being identified in addition to tetrahydrocannabinol (THC) and cannabidiol (CBD) (14).

Compared to a conventional extraction performed at ambient pressure, the PLE high pressure maintains the solvent in liquid-phase. This improves mass transfer of the extraction by increasing the solubility and decreasing limiting factors such as viscosity and surface tension.

As new extraction ideas and technologies gain traction, it’s important to understand that simple THC extraction and infusion into an edible product arose from an at-home DIY process nearly anyone with basic kitchen know-how can whip up.

First important point to know is that preparing cannabis infused foods is not a simple matter of mixing in crushed cannabis to a brownie mix, for example, and loading that mixture into the oven.

The reason is that THC is not water-soluble, and the human body is composed of up to 60% water (15). But THC is fat soluble and can bind to fat molecules, such as those in oils and other fatty ingredients. THC oil can be mixed or baked into product such as a brownie or cake by making it bind with an oil—generally olive oil, butter, or coconut oil.

To begin the extraction process and get the THC to bind with oil, the cannabis is first ground up, then put on a baking sheet and baked at 230 °F for about an hour to decarbolize it and to activate the compounds (THC and CBD). It is then taken out and allowed to cool.

A separate glass jar with a lid is then put into a large pot. The pot is filled up halfway with water. The now decarbed cannabis is put into the jar, the jar is filled up with the chosen oil nearly to the top, and the lid is screwed on fairly tightly. Then the water in the pot is heated to about 190° F and left to simmer for about three hours. It’s left to cool.

The decarbed cannabis is then filtered out of the oil using some sort of strainer (cheesecloth works), and the oil is poured into a container for future use as a cooking oil to make any THC-infused meal or treat.

Extraction from flower into a dab is also a simple procedure. There are YouTube videos demonstrating how anybody can extract rosin using a simple hair straightener and some parchment paper (16). And old tech is the foundation to some new cannabis extraction tech. One example is short path distillation (17). A short path distillation looks very similar in execution to what most people imagine to be a simple distillation apparatus, Katz said. “You have a big flask, you're heating it. It's boiling, compounds are evaporated. You get a vapor, and the vapor contains a mixture of what was in what you started boiling. The composition of that vapor will change over the course of the distillation. And when I say it changes, I mean it has higher or lower relative fraction of the thing that you're interested in, for example, the cannabinoids.”

Short path distillation is a dynamic process, starting roughly at room temperature, then heating up the cannabis. “The more volatile things come off first, such as any residual solvents, and the terpenes. When they stop coming over, there's usually overlap between the first part of the cannabinoids coming over and the last part of the terpenes coming over,” Katz mentioned. “Part of the skill of extraction is knowing when to make the cut at the overlap.”

A wiped film evaporator (18) is a variation of short film distillation that reduces oil exposure to heat. Wiped-film short path molecular distillation is common in the cannabis industry for separating cannabinoids from terpenes and heavy compounds. It’s a process to get cannabinoid-rich distillate from the molecular distillation process without affecting cannabinoid quality.

“With the wiped film distillation process, you have basically set your parameters so that only the thing that you're interested in, distills over,” Katz explained. “Everything that is more volatile than that will get caught in a cold trap. Anything less volatile than that will get passed on to the residue. So wiped film evaporators are an industrialized approach to short path evaporation. A wiped film evaporator allows you to process a lot more oil a lot faster.”

Another high-tech process is the use of a microwave (MW) reactor developed by Ethos Lean specifically for the decarboxylation of the acidic cannabinoids in cannabis inflorescences prepared for extraction into oil. Both of the steps to produce the oily extract with the MW system were carried out in the Ethos Lean's cavity with special accessories: a rotating drum for the decarboxylation process and a glass reactor with a stirrer for the extraction step, according to an article in 

In collaboration with a hospital pharmacy, the efficiency of the MW device was evaluated by comparing the results obtained with those of exhaustive decarboxylation in a conventional oven and ethanol extraction. A comparison was also made with conventional procedures in olive oil. “Thanks to the rotating drum, which is sensitive to dielectric heating, the complete and homogeneous decarboxylation of phytocannabinoids was rapidly achieved (30 min, 120 °C) without releasing the characteristic intense odor into the laboratory,” the article concluded.

Another new method of extraction was discussed at the 2024 Cannabis Science Conference by Anthony Repay, Laboratory Director of Method Testing Labs (20), involving the use of polysorbate 80 to extract cannabis and distill it into solution.

Polysorbate 80 is a synthetic compound that is commonly used as an emulsifier in a variety of foods, cosmetics, and pharmaceutical products. It's made from ethylene oxide, which is petroleum-based compound. “Why on earth would we go with the cosmetics method when we're dealing with something that is inhaled?” Repay said. “It’s about applicable methods, and things that are similar.”

He demonstrated the mixing process via a video during his presentation, showing where there was a significant association with polysorbate 80 percentage and cannabinoid concentration in a 1-in-10 dilution. “So as the relative percentage of polysorbate 80 in the solution increases, there's a corresponding increase in the amount of Delta-9 THC extracted,” he explained. “Based on this data, we can conclude that there's a statistically significant relationship between the concentration of polysorbate 80 and the extraction of Delta-9 THC, confirming the success of the extraction process.”

“For me, I think we need to get to a point where we get to an extraction efficiency and really see where it starts to tail off,” Repay expressed. “But I'd love to see at what level we start to see a true extraction efficiency where it comes into a linear kind of an algorithmic growth,” he mentioned. “The microbes, like 

 or others, showed no significant impact by increasing concentration of polysorbate 80. At the end of the day, I think we all agree that science needs more data points.”

The news coming down from the US Drug Enforcement Administration (DEA) in late April 2024 about rescheduling cannabis (21) appeared at first to be a shot in the arm for the industry. While it is generally welcomed news, and practically speaking, is likely to be years away from implementation, it will cause tech innovators from cultivators to extractors to keep a wary eye on what it means to their operations, and to the designs of the processors and equipment they use.

With a rescheduled cannabis, making compliant cannabis products using one of the currently available extractors could be a dodgy prospect if science, the regulatory process, and physicians who may soon be able to prescribe cannabis, try to understand different medical cannabis extract products. “Unfortunately, the labs are going to continue to be in a position where they have to make a choice between maintaining scientific integrity, or doing what they need to do to chase regulations that may or may not make sense, but in a way to keep their doors open,” explained Susan Audino, a chemist/chemometrician and independent consultant to chemical and biological laboratories, during the 2024 Cannabis Science Conference which took place in Kansas City, Missouri. “‘So how do I cut corners to meet these regulations that don't make any sense and still maintain a customer base so I can be not just a profitable business, but an open business?’ I see that conflict is going to continue.”

“Opening up this opportunity for research will begin to provide more data to support the contentions from the medical field right now that are using cannabis at any level,” Audino said. “Right now, we know that it works. But if I asked to see the empirical data to demonstrate why and how it works, there's been a teeny tiny amount of information out there, if any. So, I hope rescheduling will open up the opportunity for better research to improve the vast knowledge of empirical data to help support what we've been working with and knowing for a long time.”

But there is still an issue about how regulators do their job right now.

A look at how extraction techniques are driving more product innovation and whether the rescheduling of cannabis will affect extraction.


May/June 2024

Cannabis Science and Technology May/June 2024 Interactive Digital Edition

Calibration Science, Part IV: Calibration Metrics

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HLVd: The Menace to Cannabis Crops

Understanding Sources of Heavy Metals in Cannabis and Hemp Consumer Products, Part I: Is the Fractured Nature of State-based Regulations Ignoring the Evidence?

Extraction Tech Inspires New Product Development

Cannabinoid Ethers: Identification, Binding Interactions, and their ADME Properties

Cannabis Science Conference 2024: Advancing the Latest in Cannabis Research and Innovations