In my previous two columns I introduced you to Beer’s Law. In the first column (1), we examined the Beer’s Law equation and how it relates light absorbance to concentration, and how to use Beer’s Law to determine cannabinoid and terpene amounts in cannabis samples. In the second Beer’s Law column (2), I introduced the idea of totally inelastic collisions between photons and molecules and used that picture to derive Beer’s Law mathematically. We then discussed the limitations of Beer’s Law. Here in part III, we will finally come clean about what the absorptivity truly is, and how it impacts how we can use Beer’s Law.

Beer’s Law allows spectroscopy to be quantitative because it relates the amount of light absorbed by a sample to the concentration of chemical species in that sample (1,2). Beer’s Law has the following form:

where A is the absorbance; ε is the absorptivity; L is the pathlength; and C is the concentration.

By rearranging Beer’s Law, we can see how to solve for the concentration of an analyte in an unknown sample as such:

 is the concentration of analyte in an unknown sample.

Thus, measuring a concentration in a sample using Beer’s Law is a matter of measuring the absorbance of the sample, and knowing the product of the absorptivity and pathlength, εL. This product is obtained via the calibration process. Beer’s Law has the same form as the equation for a straight line as such (3):



-axis data value; m is the slope of a line; x is the 

To obtain a Beer’s Law calibration, the absorbances of standard samples containing known amounts of the analyte are measured. Then, the measured absorbances for the standards are plotted on the 

-axis, and the known analyte concentrations on the 

-axis. If the sample system being analyzed obeys Beer’s Law, this plot will be a straight line whose slope is εL, the quantity we need to use along with Equation 2 to determine concentrations of analyte in unknown samples.

Recall (1,2) that the absorptivity is the proportionality constant between absorbance and concentration. It is a fundamental physical constant for a pure molecule at a given wavenumber of absorbance, temperature, and pressure. For example, the absorptivity of pure liquid water at 1 atmosphere of pressure, 25 °C, and at 1630 cm

 is a fundamental physical constant of the water molecule. The absorptivity changes from wavenumber to wavenumber for a given molecule. Thus, the absorptivity of water at 1630 cm

. Different molecules typically have different absorptivities at the same wavenumber. For example, the absorptivity of water and acetone at 1630 cm-1 are different. Lastly, in general, different molecules have different absorptivities at different wavenumbers. Thus, the absorptivity of water at 1630 cm

 is different than that of acetone at 1715 cm

Since the absorbance is a unitless quantity, when the units of the absorptivity, pathlength, and concentration are multiplied together they must cancel out. How does this happen? The units of concentration are in moles/volume. Remember that volume has units of width x height x length, which is length cubed, or L

. Which means the units of concentration are moles/L

. The units of the pathlength are simply length or L. When we multiply the units out in Beer’s Law the results are seen in 

For the absorbance to be a unitless quantity the absorptivity must have units of L

/mole. These units may seem physically counterintuitive. Length

 is an area, and a mole measures number of molecules. How can a collection of molecules have an area? As promised previously (1,2), all will now be revealed about the mysterious absorptivity.

Recall from the last column (2) that the absorbance process is the result of what are called 

 collisions between photons and molecules. In a totally inelastic collision, all the energy in the photon is deposited into the molecule, and the photon ceases to exist. The resultant decrease in light intensity as measured by a spectrometer gives rise to an absorbance peak in the sample’s spectrum. When we derived Beer’s Law (2) we calculated the total number of collisions as being

where I is the light intensity in slab dL; C is the concentration; dL is an infinitesimally thin slab of sample and where I represents the number of photons in dL, and C represents the number of molecules in dL.

Now, only a fraction of collisions will be of the totally inelastic variety. As I said previously (2), the absorptivity represents the fraction of all collisions that are totally inelastic.

To summarize this is what we know about the absorptivity:

It is the proportionality constant between absorbance and concentration.

It is a fundamental physical constant of a pure molecule at a given wavenumber, temperature,
and pressure.

It represents the fraction of photon molecule collisions that are totally inelastic.

I could have added a fifth thing to this list, which would be the quantum mechanical definition of the absorptivity derived from things such as energy levels, wavefunctions, and wavefunction overlap (4). However, I am feeling merciful and will spare you the math behind that. How on earth can one simple physical constant have so many aspects to it? That’s what we are here to talk about.

How can something with units of length2/mole represent a fraction of totally inelastic collisions? As it turns out, characterizing collisions between microscopic particles is something physicists have been studying for a long time. For example, if you have heard about atom smashers and particle accelerators, this is what I am talking about (5). As it turns out, photon-molecule collisions are simply a subset of the types of collisions that physicists already understand.

One thing particle physicists are interested in is the probability that two particles will collide when they encounter each other. A unit that physicists use to describe the probability of two particles colliding is called the 

 (6). What on earth does this unit mean? Did you ever hear a baseball pitcher described as “not being able to hit the broad side of a barn?” Well, that is where the unit is derived from. I can relate to not being able to hit the broad side of a barn since my statistics from my Little League career as a starting pitcher are 1 1/3 innings pitched with 1 strikeout, 2 walks, 3 hits, and 4 earned runs. Needless to say, I was transferred back to right field after that performance.

 shows me trying to hit the broad side of a barn with a baseball.

Note that when I stand close to the barn, as seen to the left in the figure, the barn appears large in area to me, and the probability of my hitting it is large. If I step back several paces, the side of the barn appears smaller to me than before and the probability of hitting it goes down. If I step back a long distance, as seen to the right in the figure, the area of the barn appears quite small to me, and my probability of hitting it is very low. Now, the units of area are length

. So, the probability of my hitting the barn is determined by the apparent area of the barn from where I am standing. Thus, this is how probability has units of area.

Now, remember from above that the units of the absorptivity are length

/mole, or in other words probability/mole. Now, not to belabor the point, but a mole contains Avogadro’s number, or 6.02x10

,molecules (Avogadro constant [7]), or 6.02x10

 molecules/mole. If we divide the absorptivity in units of length2/mole by Avogadro’s number in units of molecules/mole, we obtain a quantity that is in units length

/molecule or probability/molecule. We obtain a quantity I will call the 

What the molecular absorptivity measures is the apparent area of a molecule from the point of view of a photon. If the molecule looks large to the photon, the probability of a totally inelastic collision will be high, and the absorptivity will be large. On the other hand, if the molecule looks small to the photon, the probability of a totally inelastic collision and hence the absorptivity will be small.

We stated above that the absorptivity describes the fraction of all collisions that are totally inelastic. How is this a probability? Let’s assume the fraction of totally inelastic collisions is 1/5 or 20%. This means that 20% of all collisions, or 1 in 5, are totally inelastic. This also means the odds of a collision occurring are 1 in 5, and that, folks, is a probability. So, our idea of the absorptivity describing the fraction of totally inelastic collisions is consistent with the units of the absorptivity being a probability.

If the absorptivity describes how big a molecule looks from the point of view of a photon, what things will affect this quantity? Remember that light contains an electric vector (2) whose polarity varies over time from positive to negative to positive as illustrated in 

 of a molecule is simply a description of where the electrons and nuclei are located most of the time. The electronic structure of carbon dioxide is seen in 

Because of the electronegativity differences between oxygen and carbon, the electrons in the carbon-oxygen bonds spend most of their time near the oxygen. This results in a partial positive charge, d⁺, forming on the carbon atom, and a partial negative charge, d⁻, forming on the oxygen atoms.

To tie this all together, it is the interaction between the electric vector and the electronic structure of the molecule that causes absorbance to take place. If the interaction is strong the molecule will appear “large” to the photon, the probability of a totally inelastic collision will be large, and hence the absorptivity will be large. Alternatively, if the interaction between the electric vector and the electronic structure of the molecule is weak, the molecule will appear “small” to the photon and hence the probability of a totally inelastic collision will be small as will be the absorptivity.

What variables then affect a molecule’s electronic structure and hence its absorptivity? One thing is intermolecular interactions; the strength of the interactions between a molecule and its neighboring molecules. An example of intermolecular interactions, the hydrogen bonding between water molecules, is seen in 

In Figure 4 the electronegativity difference between oxygen and hydrogen means the O-H bonds are polar and contain partial positive and negative charges. The positive hydrogen on one water molecule will coordinate with the negative oxygen on a neighboring molecule forming a strong intermolecular interaction called a 

What variables then affect intermolecular interactions and hence the absorptivity?

 Imagine a sample of water vapor. At low pressure the water molecules are relatively far apart, and the intermolecular interactions will be weak. At higher pressure the molecules are forced closer together, the intermolecular interactions are stronger, and hence the absorptivity will change.

 Again consider a sample of water vapor. Temperature is a measure of the average kinetic energy of a collection of molecules (3). When molecules collide, their electronic structures are scrambled by the impact. At low temperature the water molecules will be moving slowly, and their collisions will be few and weak. At higher temperatures the collisions will be many and strong, which is why temperature affects the absorptivity.

 Imagine a solution of isopropyl (rubbing) alcohol (IPA) in water. In pure IPA the nature of the intermolecular interactions will be different than in say, a solution of 10% IPA in water. This is illustrated in

, which shows the mid-infrared absorbance spectra of a series of five IPA in water samples, with the IPA concentration varying from 10% to 70%. These same spectra were seen in a previous column when we talked about calibration with Beer’s Law (1). Note that at the lowest concentration, where the peak is smallest, the peak top is at 2980 cm

. However, at the highest concentration, where the peak is largest, the peak top is at 2973 cm-1. This change in the position of the peak top is due to the absorptivity of IPA changing with concentration. We have seen previously that this data yielded an excellent calibration (1). Thus, if the change in absorptivity with concentration is small, Beer’s Law can still work.

 Imagine a solution of 50% IPA in water, and a 50% solution of IPA in vinegar, which contains acetic acid. As you may know, pH is a measure of acidity and basicity, where 7 is neutral and lower numbers mean more acidic (8). The pH of the IPA/water solution is going be right around neutral or 7. The pH of the IPA/vinegar solution will be acidic and about 3. In both these cases, the concentration of IPA is the same, but the chemical composition of these two samples is different. The intermolecular interactions between IPA and the water molecules will be different than between IPA and the acetic acid molecules. This means the absorptivity of IPA in these two different solutions will be different, and its spectra will be different. This means composition affects the absorptivity, and since pH determines molecular composition, it too affects the absorptivity.

To summarize then, the variables of pressure, temperature, concentration, composition, and pH all affect intermolecular interactions, and hence electronic structure. This in turn will affect how light interacts with a molecule, hence the absorptivity. The dependence of the absorptivity on these variables is why when we say that the absorptivity is a constant for a pure substance, temperature, pressure, and other conditions must be specified.

Analytical chemists sometimes define a sample’s 

 as its physical and chemical condition, including things like temperature, pressure, concentration, composition, and pH. Another way of summarizing the bullet points above is that the absorptivity is matrix sensitive, which means Beer’s Law calibrations are matrix sensitive. Therefore, spectrometers can only be used to analyze things for which they have been calibrated (which is true of all analytical instruments). In my career with Big Sur Scientific, where we sell mid-infrared-based cannabis analyzers (9) I have had people complain about their analyzer because they used it to analyze pizza and yet it gave a total tetrahydrocannabinol (THC) reading. This is because the instrument can only accurately analyze sample types for which it has been calibrated, and if you use it to analyze samples for which it is not calibrated you will get nonsensical results. The matrix sensitivity of Beer’s Law is also why when you use a spectroscopy-based cannabis analyzer there are specific sample type choices such as cannabis, hemp, medium-chain triglyceride (MCT) oil tinctures, and so forth. It is up to the user to make sure the sample type chosen in the software matches the sample type actually being analyzed so that the correct calibrations are applied, and accurate results are obtained. Again, if the sample type chosen in the software does not match the sample type analyzed, inaccurate results will be obtained.

So, there you are, the rest of the story on the absorptivity. I bet you never guessed so there was so much science behind such a simple proportionality constant.

We reviewed Beer’s Law and how it is used to determine concentrations of molecules in unknown samples. We then reviewed what we knew about the absorptivity, including that it has units of length

/area. Using the example of me trying to throw a baseball at a barn, we showed that the idea of the absorptivity describing the probability of totally inelastic photon-molecule collisions makes sense. Then, using the concepts of the electric vector of light, molecular electronic structure, and intermolecular interactions we found that the absorptivity is affected by the variables of pressure, temperature, concentration, composition, and pH. This means that the absorptivity is matrix sensitive, which means we can only use spectroscopy to quantitate sample types for which we have a calibration.

Quantitative Spectroscopy: Theory and Practice

 (Elsevier, Boston, Massachusetts, 2002).

4th Edition (Wiley, New York, New York, 2013).

https://en.wikipedia.org/wiki/Particle_accelerator

https://en.wikipedia.org/wiki/Barn_(unit)

https://en.wikipedia.org/wiki/Avogadro_constant

, 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: 

Articles

Cannabis Analysis 

Part III discusses more on Beer’s Law and why absorptivity is important along with some of its advantages and limitations.

Beer’s Law, Part III: Demystifying the Absorptivity

How did you get interested in the cannabis industry?

 Well, I think the cannabis industry became more interested in me before I was interested in it, and I can explain that. I’ve been in LED lighting to various degrees for about 20 years, really since the first LED lighting fixtures came out. I was in Europe for five years, running a couple of different companies there.

I had Osram as a customer and when Osram bought Fluence in 2018, they wanted to hire a CEO to drive the business because the founders were going to exit. So, they reached out to me and said, “You want to come take a look at this company in Austin, Texas?” and one thing led to another, and that’s how I took the job.

It wasn’t like I was seeking it out. It kind of found me. But once it found me, it’s been a really great relationship. The cannabis industry for my company and for myself has been a spectacular, spectacular experience.

A lot of people set out as a mission to go get into cannabis. And it’s not that I didn’t want to, I just really never had thought about it back in 2018. But what they wanted to do with the company was very intriguing. And when I took a look at the market and the growth potential, I was hooked and then I really started learning about growing cannabis and what the different customer needs were and all that.

Can you tell us a little bit about Fluence?

 Fluence was founded by three gentlemen in Austin, Texas in 2015. They had an idea that they could make a kind of superior grow light and bring it to market. And by about 2016 or 2017, they had not only come up with a great set of products—a small portfolio of products—but they were also taking advantage of what was going on in cannabis at the time because a lot of the big players in lighting were quite hesitant to get into this space because of their boards of directors, their ethical policies, and whatnot. There were a lot of companies that wouldn’t touch it.

Fluence came up with a great product at just the right time when really Canada and Colorado were taking off and got the lion’s share of the market by bringing really superior products with a ton of research behind it, and that really just put the company on an unbelievable growth trajectory.

By late 2017 or early 2018, they realized that in order to keep growing at the pace that they were growing, which is essentially doubling revenues every year, that they would need to go find either some outside money to fuel the growth or sell the business. So, they elected to sell it, which obviously opened up a great opportunity for me. I took over in 2018 and from 2018 to 2021, with the exception of 2020 (the COVID year), we’ve continued on roughly 100% top line growth. It’s grown very, very quickly and very large in a short amount of time, at least to my experience of growing companies.

What is the best type of light for cannabis cultivation?

 It really depends on how you’re going to grow cannabis. There are a couple of different schools of thought out there. Number one is the traditionalists that you grow cannabis with the sun and as the sun goes, the plants go. And that’s one way to do it.

Then when you go inside and you want to grow it using artificial light, you can do it in a greenhouse, which is a big open glass structure flat. All the plants are on the same level and you’re using a mixture of sunlight and artificial lighting, usually LED lights.

And then there’s another way that’s becoming very, very popular now, which is vertical growing cannabis. Instead of going out left to right, you go straight up, and you could have two, three, four, or five levels of these big, huge racks. The lighting for the racks and the lighting for the greenhouse are very different because of the proximity of the light to the plant.

In a greenhouse, the light is much, much higher up in the air. By default, that is extremely powerful. The rack growing, the lights are right on top of the plant, usually six or seven inches, maybe even a little bit less. The intensity can’t be as much because it would kill the plant.

It’s difficult to answer that question, what’s the best type of light. I would say the best type of light generally is an LED light. You can get a lot more control with LEDs. You can change spectrums. You can manipulate the plant quite a bit more than you can with traditional light sources like high-pressure sodium (HPS). I would just say generally, an LED light, but then you get into the specific type of growing that you’re doing.

 You can come up with whatever spectrum you want. At Fluence, what we’ve done is we’ve pioneered the broad spectrum, which is a spectrum that exactly mimics the sun. And that was one of the things that Fluence really changed the game on.

Growing plants inside had historically been done with either high-pressure sodium lights, which are very yellowish in tint or LED lights that were kind of a mixture of blue, purple, and red. And those blue-purple-red lights are very, very difficult to work under. It’s extremely taxing on your eyes.

You can’t see without some kind of glasses like real close-up views of the plant if there’s bugs or mites or infestations or mold, and it’s just really difficult to work under. So, what Fluence did after a couple years of research has showed that the best way to grow this plant is by using broad spectrum, which looks white with some kind of red and green dots in it.

But if you look at the spectrum on a piece of paper, it’s almost exactly the spectrum of the sun. And what we found is that’s the most successful. We led the market with that in 2016 and 2017, and now virtually, every single lighting company out there is using broad spectrum.

I don’t know what the exact percentages are, but I would guess more than 75% of the people selling LED lights to grow cannabis are selling lights that are broad spectrum.

How did you research LED grow lights in the cannabis industry? What other research is your company working on related to cannabis cultivation?

 We do a ton of research, but basically, because we’re in Texas and we don’t have a license to grow cannabis, we’re highly dependent on partners. We have a wonderful working relationship with Texas Original Compassionate Cultivation, which is one of the three licensed cannabis growers in the state of Texas for medicinal.

We have a huge space in their grow where we are doing research around the clock on all types of spectrum and form factors and light intensities. And we also do this with a lot of our customers in states where it’s legal, such as in California, Michigan, and Massachusetts.

Even in Canada, we have R&D grow rooms at our customers’ sites that we run, but we’re running it under their license because we can’t run the product in Austin. We’re working with these customers to understand what the difference between different cannabis cultivars are and how light intensity impacts the growth of those cultivars.

[Note: It's not legal to grow cannabis in Texas without a medical license. Fluence's research team has partnered with one of the three licensed cannabis producers in Texas to study best practices in growing cannabis.]

For example, put it in vegetable terms, you have cherry tomatoes, beefsteak tomatoes, and Roma tomatoes. Those are just three types. Inside of those types, there’s hundreds of different cultivars. What we’re trying to do is find out how we can use our lights and change or manipulate the spectrum to impact specific events in a plant of a specific cultivar.

You’re really getting down into the subset of, now we have this one strain cultivar, how do I get this plant to grow either faster or more flower or higher THC, different cannabinoid profile? There’s a lot of things that you can manipulate in the plant by using lighting, but it really depends on what cultivar you’re using.

When you ask the question, what other research are we doing, we’re constantly researching the effect of various different types of spectrums on various different types of cultivars and trying to build a database of relationships between these. For example, let’s say 20 cultivars are most similar, they grow generally the same, but these 20 grow better. And that’s a metric where you have to decide what does grow better mean? Bigger, faster, more flower, higher THC under a different light spectrum? We’re finding that different spectrums affect different cultivars quite substantially.

If we have a customer that’s going to bring up a grow, let’s say, a million square feet of cannabis plants, which is a lot of plants. And we know what cultivars they’re going to be growing, specifically what strains, we can prescribe a lighting recipe that will maximize either their cycle times to grow, the plant biomass or, like I said, the different THC and cannabinoid profiles.

This is the part for me when I started to understand what type of research we were doing when I came to the company, I was fascinated. And We're doing the same thing in commercial agriculture. Not just cannabis. It’s very similar to figuring out how do I get this basil plant to grow fuller, but also to last longer on the shelf by two or three days?

Because if the basil grower—cannabis is a little bit different in this regard, but I’ll use this as an example because it’s a very good one—if the basil grower can guarantee the supermarket that you’re going to get four more days of shelf life off my product before it starts to wilt, they can get a higher price. Consequently, if the cannabis grower is growing the same strain as everybody else around them, but we can teach them how to get the THC 20% higher, or we can reduce 20% of the time it takes to grow, we can help them make more money. There’s a lot that goes into it, and it all starts, and it is driven by lighting, which kind of surprised me when I came in here.

Why are LED lights becoming the industry’s “go-to” in horticultural growing?

 There’s a number of different reasons. I have it from my perspective and there’s certainly the grower’s perspective, which is going to be a little bit different. Ultimately, you can control what you’re doing much more accurately using LED lights because you can tune them.

You can dim them, they can go higher intensity, lower intensity, you can have different spectrums. The traditional way to grow cannabis inside with high-pressure sodium lights, there’s one light, it’s one color, it is what it is, and you grow what you grow. But also with high-pressure sodium lights, really good growers will wind up changing the bulbs out because high-pressure sodium bulbs deteriorate very, very quickly.

Then you’re swapping bulbs out two or three times a year. What do you do with those bulbs? You throw them in the trash. They’re going to a landfill. LED lighting lasts 50,000 hours before it really starts to degrade, and that’s about 11 years. We have not yet gotten to the point where the lights that we’ve sold into the market are even close to being needed to be upgraded.

But what we can do when that time comes is we can save the light, take out the LED part of it, recycle that, and then put another LED in. You have a sustainability component; you have a control of your grow component. LED lighting has proven, by far over the last two or three years to grow healthier, fuller, higher THC plants than HPS.

And then lastly, you have electricity. And this is now becoming a bigger and bigger issue. We really struggled at the beginning to make the return on investment based on electricity, even though the LED lights consume about 40% less energy than a high-pressure sodium light does.

You’re literally saving 70% on your electric bill. But when this all started, electricity rates in the United States and Canada were very, very low, four or five cents a kilowatt hour. You needed a lot of kilowatt hours to make that back. But what’s happening now with the kind of global supply chain shortage and the price of oil going up and the price of electricity going up, that is now becoming a much, much bigger factor. So much so that we have customers that are growing under traditional high-pressure sodium lights that have stopped growing because their electricity bills are killing their profits. And now they’re really stuck. Do they go out and spend the money on LED lighting to get a lower electricity bill or do they wait for the cost of electricity to come down? I would say there’s three big things that make kind of LED lighting the go-to: control, sustainability, and electric consumption.

Can you tell us about some of the results you found in the

“2021 ‘State of the Cannabis Lighting Market’” report?

 I think the most important takeaway for us is that LED adoption is on the rise. We’ve modeled this thing. We do it every year. We sit down and do a lot of market modeling around the world, and we still can’t believe that these adoption numbers are as high as they are.

We had it about 20% less. LED usage for cannabis cultivation is up more than 45% for all stages of plant growth since the first report in 2016. A majority of about 60% of those growers that we speak to that aren’t using LEDs during flowering are considering doing it in the next six months.

That data says this is still growing very quickly and very closely emulates what we’re seeing from a customer count revenue and overall growth of the company. It’s really great to see that it’s being adopted so much. When I first came in 2018, there were a lot of concerns about the reliability of LED lighting. And the experience that people had had in the past was buying cheaper LED lights or stuff that was made in Asia. Then there were problems with the power, and a lot of fixtures catch on fire if you don’t build these things right. LED lighting got a real bad reputation in growing plants for a long time.

With that, I think it’s just about gone. In 2018 and 2019, the kind of the tide came in of LED lighting and from 2019 to now, it’s what people talk about when they build to grow. Can I afford to use LED lights or not? Because the important part is that a high-pressure sodium light is about $250 where an LED light is like $800 or $900.

You have a pretty staggering difference in cost, but the electricity difference alone is a huge number. And then if you talk about LED lightings are more efficient and you can grow one more full cycle of plants in a year. I mean, if you’re pulling down a 10,000-plant crop and you can grow 10,000 more plants in a year, that’s a direct hit to your bottom line. It’s really what growers are paying attention to.

I would use the word astronomical. I can’t believe it is taking on so quickly and so much. And because you also have a lot of these growers, we’ll talk about these people. These are people that most of them were growing illicitly for a long time. They have small growers in either their house or their basement or their backyard.

You get into a large-scale commercial grow with 10,000 plants, there’s not very many people in the world who have 5- or 10-years’ experience with that. And having a reduction in the amount of variability is always going to be better when you’re taking on something that big. That’s exactly what LED lighting does. It allows you to control the variables a lot easier.

The Cultivation Classroom

When it comes to cannabis cultivation, growers have their own methods on how to get the best products from their plants. Through using different soils, irrigation practices, lighting, and other approaches, each item plays an important role in how the plant matures. In this interview, David Cohen, CEO of Fluence, discusses the rise in LED lighting methods and how it can be the best tool for the industry.

LED Lights Lead the Way in Cannabis Cultivation

Extraction technology is one of the faster changing parts of the cannabis science business. More concentrates and products are coming out all the time. But there is always a search, more of a scientific yearning, for a better, cheaper, or safer process than the current methods.

It’s all about what you want to extract, then essentially working backward from there. There are new processes being invented all the time, and ideas generated by other industries to review and incorporate, as extractions and the products made from extractions becomes more popular.

It’s time for a reboot about what extraction means, where it’s being used, and why it’s not the chemist’s mystery that some believe it to be.

This “Tech Innovations” column will quote top thought leaders in extraction developments and find out what’s being developed now, what’s coming next, and how extractions are better and safer than ever before.

Cannabis extraction should not be viewed as a “black art,” but a quantifiable scientific process, according to Markus Roggen, president and chief science officer of Delic Labs, who describes himself as just the chemist who counts molecules and not the guy who does the medical studies.

“An artist says that they will always make a masterpiece because it cannot be ignored and cannot be used as a consumer packaged good,” he said. “The businesspeople at Coca Cola know exactly how much it will cost them to make their product. It should not be a surprise. And so therefore, optimization is important.”

Roggen is now employing machine learning (1) to the extraction process. He explained why he is doing that, and how he is getting there. “Extraction has the goal of removing the compounds of interest, such as cannabinoids, terpenes, and maybe other parts, from the whole plant matrix, and separating them from all of the unwanted compounds like waxes and sugars.”

The cannabis plant is rich in compounds, he said, and different extraction processes had to be developed for them—solvent, solventless, CO

, and other new and familiar methods (2). How extraction usually works is that the extraction operator would step up to one machine, look at the machine, look at the cannabis they have, and then from experience or from a more structured optimization process, would dial into the machine the extraction process until he got what he wanted. “That’s how we normally did it,” he said.

But there are a limited number of experiments to do in finding the right optimization process just because of the time of day, the number of materials, the cost, and the operating hours. “So, you might be doing two experiments to maybe 20 experiments to find the right setting for you,” said Roggen.

The operator must consider that there are cannabinoids, terpenes, sugar, waxes, water content, then different strains of cultivars, and different sizes and different instruments, but also different concentrate products to be made, he added. “We might want something solid, or powder or edible,” he said. “We might want to have a very high terpene oil for one product, and we want to have just cannabinoids for another product. So now if we want to optimize for all these various factors and outcomes, it becomes impossible to do experiments for it, because we have to do too many experiments to figure that out. That was our problem and why we considered machine learning.”

The intended goal of machine learning is to understand the process, Roggen explained. “That’s so that the operator makes the right product in the most efficient way, but also so that the business side of the company understands all the costs, is able to reduce the costs as much as possible and produce the most reliable and consistent product they can,” he said.

Extraction is an old technique for the food processing industry (3). It appears that there should be no reason to re-invent the process for the cannabis industry. But there are many variables with cannabis—the most difficult being that cannabis is illegal—so the mechanical and agricultural techniques that have been researched for decades for other food products don’t exist for cannabis, Roggen explained. “We have a lot to catch up to. Cannabis by itself is a very complex plant. And we are interested in such a variety of compounds that a classic way of separation or extraction that you might see in the perfume industry doesn’t work anymore,” he said.

Enter the beginning of machine learning. “With cannabis, we don’t have a big data project. We don’t have enough data. All machine learning is based on the idea that we take the existing data we can find, develop a basic understanding of how extraction works based on the data, and obviously some scientific principles, and then use a machine learning algorithm that is constantly improving,” he said. “So, it takes the existing data, makes a best guess about the process, then takes the learnings from that experiment to the next experiment into improving its algorithm. So, if we compare our current machine learning to an existing operator, we can improve the operations by 50% easily, then maybe 20% the next time.”

Roggen is also working on extractions with psilocybin (4) since the Canadian government regulations allows research licenses for psilocybin and a host of other psychedelic compounds for his lab in Vancouver. “So right now, we have LSD, MDMA DMT, Ibogaine, 5-MeO-DMT, and all of those compounds,” he said. “The first question we focus on is analytics, because if you get your hands on psychedelic mushroom, there’s a little bit of psilocybin in there, and a lot of psilocin, which is almost twice as potent as psilocybin. Having a lot of psilocin in a mushroom is good. The problem is that it’s very unstable and degrades and oxidizes very quickly. So, you actually want your mushroom with a lot of psilocybin. That’s the most stable form and then you only have to control the transformation to psilocin when you make your tea or when you ingest it.”

In a testing laboratory during the sample preparation method, operators are degrading the mushroom, so they’re changing the result while they’re testing it. “The test methods are not yet well developed. That is our main focus right now—to develop better test methods to be able to establish the right concentration in the mushroom and not the artifact that we see after we destroy the mushroom.”

Nick Tanem, the owner and operator of Essential Extracts, a public speaker and activist, said he is the guy who coined the word “solventless” (5). “I reserve the term solventless for mechanical separations, but it’s actually not an extraction,” he said. “Whereas butane, ethanol, or CO

 would be used in extractions, where you’re actually extruding the oil from within the trichome head.”

Solventless is more of a mechanical separation rather than an extraction, he said, meaning that an operator is mechanically separating the trichome head from the plant material. “Once we are talking about rosin, we are talking about extruding those oils via mechanical means without the use of any chemical solvents,” said Tanem.

Most, if not all, of today’s forms of extractions going for different consistencies and new end products can be done by mechanical means, Tanem explained. “It’s for some of the newest products on the market in the last two to five years, like live rosin cartridges, because we’ve been able to mechanically separate this oil without the use of any chemical solvents and get it into a vaporizer or cartridge form,” he said.

With states like Pennsylvania outlawing any additions or subtractions to a vaporizable form, such as added botanical terpenes or even added cannabis-derived terpenes back into a formula, live rosin cartridges are becoming even more popular. “I’m getting a lot more work,” he said. “That’s where a lot of the industry is going, understanding that we’re able to now recreate these consistencies and products without the use of chemical solvents.”

Borrowing from the Freeze-Dried Fruit Food World

Tanem shared that his clients are constantly asking about the cartridge technique and how to get the rosin form into the right viscosity that’s usable in the vaporizable form for either the cartridge or any other the hardware that’s out there on the market. “A lot of my clients are also asking about specifics on the freeze dryers,” said Tanem (6). “We brought freeze dryers in about 2015 from the freeze-dried fruit world into the cannabis world.”

The freeze dryer allows an operator to mitigate the chance for microbial contamination. “When we’re talking about mechanical separations, we’re using water. When we use water combined with plant material, there’s the chance for more microbial growth,” he said.

With a freeze dryer, an operator can remove 100% of the plant matter, and 100% of the water. There is no chance for mold microbial growth at that point. “So that’s a really, really big step in the scaling up or the industrializing of our industry and creating safer products,” he added.

Tanem said that the whole solventless process is huge. “In the beginning, it didn’t get as much traction as I thought it would. And at this point, you know, almost 10 years later, after coining that term, it’s a huge part of the industry,” he said. “People are asking about scaling up that process.”

That’s what Tanem has been focusing on: Scaling up the processes, going bigger, trying to compete with the big money coming in. “But doing that while retaining our craft, the knowledge and skill set that we’ve learned over the last couple of decades here in this space,” he added.

Darwin Millard is a mechanical engineer by training who specializes in mechanical and solvent-based extraction methodologies for isolating the various phenolic secondary metabolites from botanicals. “It was like, as a mechanical engineer, I could build and design slurry pumps for the fracking industry, or I could jump headfirst into Colorado’s fledgling medical cannabis program at the time. So, I did that. And I wouldn’t change anything for the world,” he said.

Millard is the chief science officer for Final Bell, based in Canada, and Final Bell is the Canadian arm of a multinational operator that has several larger copacking and coprocessing facilities that are intended to provide those services for the legal cannabis marketplace. In his role as chief science officer, he is helping the company with research and development into new and labor and cost saving process improvements and systems.

Final Bell does solventless extractions in bulk, as well as big cartridge filling and co-packing for various clients. With a broadening product range, and an equipment and process system evolution underway, what is being done with extractions today? “It more or less depends on what your end product is,” Millard said.

Millard said it’s important to ask yourself these questions: What are you trying to make? Are you trying to compete in the highly competitive concentrates and extracts game, where it’s all about hype? Do you have the right strains? Or are you just trying to make a bulk ingredient that you are going to sell at the cheapest price possible to a larger copacker or coprocessor who is making products for other people? Or are you going to try to make some small batch artisanal terpenes run?

“If you don’t know what you’re trying to extract, or why you’re trying to extract it, then you could theoretically make anything with anything,” he said. “And there are other implications you might want to take into consideration when looking at these various different types of extraction systems that are out there.”

Extraction is not a dark science because people have been extracting various analytes of interest from complicated botanical mixtures for a very long time, Millard explained. “It’s almost unimaginable to think about a plant as something that we’ve kind of coevolved with for so long and know so little about, in comparison to if we were to find an unknown plant, flower, or frog species or insect or something in the Amazon,” Millard said. “But with cannabis, it’s almost like we’ve just discovered some new life form at the bottom of the ocean.”

The issue of heavy metals and other contaminants in extracted products seems to be under control for now, but there is still a significant issue with them in the black market. “The cannabis plant is a very strong phytoremediator of heavy metals and other elemental impurities,” he said (7). “So, depending on where and how you are growing it, there could certainly be opportunities for elemental impurity contamination.”

Contaminants that are of concern to anyone growing an agriculture product include pharmaceuticals and personal care products, hormones, steroids, alkyl-phenols, flame retardants and pesticides. They can get pulled up into a crop as a crop grows, and end up in the food chain even after processing. That’s where standards development organizations such as the American Society for Testing and Materials (ASTM [8]) International and their technical committee, called D37 on Cannabis (9) comes in, trying to create standards that will help promote product quality and ensure consumer and environmental health and safety.

There are many forms and many methods of cannabis extraction being used today. But these machine processes need more controls, and more controllable features, to reproduce the same concentrate every time. That’s one of the goals of a medical cannabis business—to make formulations that are consistent and can be counted on by the patient. But beyond the medical market, general consumers in adult use states have an expectation that their products will be safe and consistent as well.

What is left to explore today is operator education of the extraction process, and the bringing together of more of the brain power of engineers and extractions operators to answer common problems or explore new concepts. When these minds meet, the future of cannabis extractions will surely be all the stronger.

https://www.sas.com/en_us/insights/analytics/machine-learning.html

https://www.cannabissciencetech.com/view/new-extraction-technologies-lining-be-game-changers

http://digitalknowledge.cput.ac.za/bitstream/11189/2573/4/Lloyd_Philip_J_Van%20Wyk_J.pdf

https://www.cannabissciencetech.com/view/solventless-extracts-an-overview

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7022747/

https://www.frontiersin.org/articles/10.3389/fpls.2020.00359/full

https://www.astm.org/ptphfl2022.html#heading0

 has written for many cannabis publications, and organized or moderated sessions at national and international cannabis trade shows. He was voted the 2018 Journalist of the Year by Americans for Safe Access, the world’s largest medical cannabis advocacy organization.

Tech Innovations

Different extraction processes, new products, and new equipment combine to create the perfect storm of better, safer extractions.

Taking a Measure of Evolving Extraction Technology

I recently spoke with 2022 Cannabis Science Conference West psychedelic science track speaker, AC Braddock to discuss her upcoming presentation entitled “Psychedelic Sustainability.” AC is an industry pioneer and CEO of Eden Labs, a trusted innovator of extraction and distillation technology for the cannabis and health products industries since 1994.

We’re really excited that you’re going to be joining us this year at our newly launched psychedelic science track. AC, you have been a friend of the show for many years and you typically have spoken in our analytical science track about the extraction process with cannabis products. We’re excited to switch it up a little bit this year and give you the chance to speak about one of your other fortes in the industry. If you don’t mind, would you share with the readers what initially got you involved in the cannabis and psychedelic industries?

: The initial push was in the ‘90’s, I was looking at triple A personality types who are really driven and stressed out and had lost connection with their health, their wellness, themselves, maybe even nature—I was looking at finding a way to use plant medicine and nature to help these individuals reconnect. That is the bottom-line and driver of everything I do - - it all has to do with all plants and plant medicine.

Can you share a little bit about your work with Eden Labs and exactly what Eden Labs does for those that might not be familiar?

: Eden Labs is a 27-year-old botanical extraction and distillation company and we work with a wide array of different botanicals. The founder, Fred Chester, started working with cannabis in the mid-90s and then brought commercial extraction to the cannabis industry in 1996.

My work with Eden Labs is trying to share, teach, and educate about plant medicine and bring botanical industries back around to the forefront - - because we have forgotten about the healing power of plants in our culture and it’s truly a loss. It’s sad for humans; we have lost this knowledge and we need to be reminded about the unbelievable benefit plants provide, but we’ve also lost that spiritual connection to our planet. I think that is very obvious in our world today.

As an example of how I try to teach and educate, specifically with Eden, before there were any conferences talking about extraction, I lobbied hard to have those conversations included. I’m sure I was quite annoying, but no one was talking about extractions and how to do them…. Now that is the primary thing people talk about.

You really have been a pioneer in this industry for many years. So, what was it like really being one of the first female leaders in this industry that was a pioneer in the early, early days and now cut to 2022? There’s a lot of different groups that are talking about inclusion, the LGBTQ community, people of color, unwriting the war on drugs. We’re seeing more women’s organizations now, but I’m talking back to a time where you would look around a room and you probably would feel alone. What was it like then? And what is it like now seeing a lot more women and minority involvement in general?

: There was definitely a time in the early days when there would be 100 guys in a room and two women. It was interesting, but it’s not really all that different from any other business industry. So, it was kind of on par. You learn as a woman and as a person of color how to deal with that inequality. And it’s never comfortable.

But as the industry grew, a lot more people started jumping in. This was before you had to have millions of dollars to be able to start a business. There was tremendous growth - - of people of color and women owning and running businesses. Then that switched and those numbers dropped. We talk about balance but it's not really balanced without equity. If there’s not equity, you’re off balance. There’s a loss of creativity and there’s a loss of stability and there’s a loss of vision. Unless you have all of these people at the table, we’re never going to develop into a truly wholesome industry.

It’s a cultural shift, obviously. In order to seek equality and equity in business there has to be a shift from businesses just focusing on money and profits, to businesses focusing on people and the solving of problems. And as science-based people, that’s what we do. I mean, we’re here to solve problems.

Ideally the business world catches up to the kind of philosophy in which it understands that it’s about health and wellness and happiness - - what’s more important here? What’s going to really push humanity forward? Or are we just going to accept a stalemate or go back completely?

Your talk at Cannabis Science Conference West is called “Psychedelic Sustainability.” Can you share a little preview of what people might hear in your talk? What are your thoughts on how quickly the psychedelic industry is emerging?

: Well, I think 2020 and 2021 were extremely painful for people, and we were stuck inside, which means we were inside ourselves. This period allowed us to slow down and take some time for reflection. While all of this crap was going on in the world that was, you know, really scary and really disturbing - - It also allowed some people to think, “Oh, I’m at home, I can experiment a little bit.” So, I think that that was really the push and the drive for it to happen faster.

I think people also couldn’t really connect with anybody during this time and psychedelics, traditionally, in a shamanistic practice, have always been centered on community connection. It’s how people gathered together. It’s how they shared how they’re going to treat each other, the vision for what they were going to be doing for the next year or two... What I want to talk about is that connection and the fact that psychedelics and ethnogens are always used ritualistically. It’s therapeutic. Therefore it has to be ongoing, which means you can’t keep flying to South America to do this because that’s just not environmentally conscious - - it’s not sustainable - - And you’re diluting those cultures, and overusing someone else’s methodologies to find what you really need…a community that you have at home or that already exists for you to tap into.

There are methodologies and rituals that have been historically in your area where you live, but these rituals have been denigrated to the point that they’re non-existent or on life-support. You…we…have to revive them - - then we have a consistent, sustainable, therapeutic way to reground and connect with ourselves and nature and community.

Obviously, we are the Cannabis Science Conference, so we have to feature all the great science and research. But with the psychedelic science track, it was also important to us to feature a number of indigenous voices who have been the gatekeepers of this knowledge of medicine for millennia.

: Indigenous voices should absolutely be involved. We have a lot to learn from indigenous communities because they are closer to those plant medicine connections - - culturally, Western society has lost it. But these communities are also asking that we be respectful and conservative and understand the primary points of why they developed and have this connection. And so our curiosity and desire to learn doesn’t become spiritual tourism.

We have had some really interesting conversations about one of the downfalls of certain psychedelic drugs can be the digestive issues. A lot of times if people are trying psilocybin, for instance, sometimes the way their body metabolizes it, they can tend to have upset stomachs and issues with that. What are your thoughts on this topic?

: Well, we, at Eden, are very interested in all of the plants and have come up with a way to concentrate and do a really beautiful extraction of psilocybin that removes the nausea. It additionally increases the onset and shortens duration a little bit, which I think is a benefit for a lot of people.

Then when you start to put it in products, it doesn’t taste like mushroom because a lot of people don’t like the flavor. I personally like the taste, but a whole lot of people don’t. So, we’re solving some problems (perceived problems) with it and increasing efficacy. It’s been really exciting and it’s ongoing. But right now, what we’ve come up with is pretty good. It’s pretty exciting.

Well, that’s so important because just like cannabis, even now, there’s a lot of products in the market that are not regulated and a lot of people that are extracting, however they’re doing it, putting it into chocolate bars, putting it into candy or whatever the case may be. So really having that science behind the extraction process and trying to get into a more regulated place with that is really a good place to be. Is your role at Eden Labs in the psychedelic science space centered around processing and extraction, just like in cannabis then?

: Yes. We’re constantly working on botanical extractions and finding safe ways to provide therapeutic plant medicine to people, so you can feel good about it. You can titrate it as it’s needed. But I’ve also been doing some sitting with people in some guided journeys for a few years, which has been very rewarding for me. It’s been lovely to see people really settle into themselves and lose some of their fears.

Everybody has these insecurities or fears—we all have them. And getting into these alternative states where you have more clarity, you’re thinking, “well, why am I worried about that? Why do I have that fear? I don’t need to.” It’s a really nice centering. I have just loved to be a part of seeing people find that strength within themselves.

What would you like to see for the cannabis industry in the next five years?

: We have learned so much of what not to do in the cannabis industry.

To answer the question, what I have always wanted to see—what I continue to want to see, which still hasn't happened—I want to see companies who understand that they are creating a market. And what an amazing opportunity that is to create an entirely new market, an entirely new industry, and do it right. To do it based on the science, to do it based on the genetics of the plant and the genetics of people, and use those marketing opportunities to educate consumers, which still isn't really happening. We're just seeing a lot of marginal products being introduced in every new industry.

As a company, we've seen every single new market come on, every single one of them, and they make so many of the same mistakes. I just would love to see it mature faster and have the companies come together, to have the cannabis industry lobbying with the natural products industry to create a much broader, bigger, stronger, and more powerful force around plant medicines of all kinds so that we can push through legislation and regulations that make sense and stop harming people and the industry.

AC Braddock, the CEO of Eden Labs, shares a preview of the talk she plans to give at Cannabis Science Conference West as well as other industry insights.

May 2022

Beer’s Law, Part III: Demystifying the Absorptivity

LED Lights Lead the Way in Cannabis Cultivation

Taking a Measure of Evolving Extraction Technology

Sustainable Psychedelics: A Chat with CSC West Speaker, AC Braddock

Medical Cannabis Is Here and It’s Here to Stay: How Americans for Safe Access, the Nation’s Largest Member-Based Cannabis Advocacy Organization, Protects Patient Rights

Fundamentals of Supercritical Fluid Extraction: Using Carbon Dioxide as an Environmentally Friendly Solvent for Extraction of Cannabis

Improving Quality in Cannabis Testing Laboratories: Making ISO/IEC 17025 Work for Your Laboratory and Customers