Terpenes are a group of volatile, unsaturated hydrocarbons found in the essential oils of plants. They are responsible for the characteristic smells and flavors of most plants, such as conifers, citrus, as well as cannabis. Over 140 terpenes have been identified to date and these unique compounds may have medicinal properties. Caryophyllene, for example, emits a sweet, woody, clove taste and is believed to relieve inflammation and produce a neuroprotective effect through CB2 receptor activation. Limonene has a citrus scent and may possess anti-cancer, anti-bacterial, anti-fungal and anti-depression effects. Pinene is responsible for the pine aroma and acts as a bronchodilator. One theory involving terpenes is the Entourage Effect, a synergistic benefit from the combination of cannabinoids and terpenes.
Many customers ask technical service which instrumentation is best, GC or HPLC, for analysis of terpenes. Terpenes are most amenable to GC, due to their inherent volatility. HPLC is generally not recommended; since terpenes have very low UV or MS sensitivity; the cannabinoids (which are present in percent levels) will often interfere or coelute with many of the terpenes.
Headspace (HS), Solid Phase Microextraction of Headspace (HS-SPME) or Split/Splitless Injection (SSI) are viable techniques and have advantages and disadvantages. While SPME can be performed by either direct immersion with the sample or headspace sampling, HS-SPME is considered the most effective technique since this approach eliminates the complex oil matrix. Likewise, conventional HS also targets volatiles that include the terpenes, leaving the high molecular weight oils and cannabinoids behind (Figure 1). SSI eliminates the complexity of a HS or SPME concentrator/autosampler, however, sensitivity and column lifetime become limiting factors to high throughput, since the entire sample is introduced to the inlet and ultimately the column.
The GC capillary columns range from thicker film, mid-polarity (Rxi-624sil MS for instance) to thinner film, non-polar 100% polysiloxane-based phases, such as an Rxi-1ms. A thicker film provides the best resolution among the highly volatile, early eluting compounds, such as pinene. Heavier molecular weight compounds, such as the cannabinoids, are difficult to bake off of the mid-polarity phases. A thinner, non-polar film enables the heavier terpenes and cannabinoids to elute efficiently and produces sharp peaks. Conversely the early eluting terpenes will often coelute using a thin film column. Columns that do not contain cyano-functional groups (Rxi-624Sil MS), are more robust and have higher temperature limits and lower bleed.
For the GC detector, a Mass Spectrometer (MS) can be used, however, many of the terpenes are isobars, sharing the same ions used for identification and quantification. Selectivity is the best solution, regardless of the detector. The Flame Ionization Detector (FID) is less expensive to purchase and operate and has a greater dynamic range, though it is not as sensitive, nor selective for coeluting impurities.
By accurately and reproducibly quantifying terpenes, cannabis medicines can be better characterized and controlled. Strains, which may exhibit specific medical and psychological traits, can be identified and utilized to their potential. The lab objectives, customer expectations, state regulations, available instrumentation, and qualified lab personnel will ultimately determine how the terpenes will be analyzed.
On Monday, March 6th, Shimadzu Scientific Instruments, a leading laboratory analytical instrumentation manufacturer, announced the launch of a new product focused on cannabis, according to a press release. Their Cannabis Analyzer for Potency is essentially a high-performance liquid chromatograph (HPLC) packaged with integrated hardware, software, workflows and all the supplies. The supplies include an analytical column, guard columns, mobile phase and a CRM standard mixture.
The instrument is designed to test for 11 cannabinoids in less time and with greater ease than traditional HPLC instruments. In the press release, they claim “operators are now able to produce accurate results with ease, regardless of cannabis testing knowledge or chromatography experience.” One very unique aspect of the instrument is the lack of experience required to run it, according to Bob Clifford, general manager of marketing at Shimadzu. “We have our typical chromatography software [LabSolutions] with an overlay that allows the user to analyze a sample in three simple steps,” says Clifford. Those in the cannabis industry that have a background in plant science, but not analytical chemistry, could run potency analyses on the instrument with minimal training. “This overlay allows ease of use for those not familiar with chromatography software,” says Clifford.
The instrument can determine cannabinoid percentages per dry weight in flower concentrates and edibles. “Once you open the software, it will get the flow rate started, heat the column up and automatically begin to prep for analysis,” says Clifford. Before the analysis begins, information like the sample ID number, sample name, sample weight, extraction volume and dilution volume are entered. After the analysis is complete all the test results are reported for each sample.
Because laboratories wouldn’t have to develop quantitative testing methodology, they argue this instrument would save a lot of time in the lab. “After one day of installation and testing, users are equipped with everything they need to obtain cannabis potency results,” states the press release. According to Clifford, method development for potency analysis in-house can take some labs up to three months. “We can bring this instrument to the lab and have it ready for testing almost immediately,” says Clifford. “The methods for this instrument were developed by a team of twenty scientists working on different platforms at our Innovation Center and was tested for ruggedness, repeatability and quantitative accuracy.”
The instrument’s workflow is designed to meet three methods of analysis depending on testing needs. The High Throughput method package can determine quantities of ten cannabinoids with less than eight minutes per sample. The method was developed in collaboration with commercial testing laboratories. The High Sensitivity method package adds THCV to that target analyte list with ten minutes per analysis. The method provides the sharpest chromatographic peaks and best sensitivity. The High Resolution method package offers full baseline resolution for those 11 cannabinoids in less than 30 minutes per analysis and the ability to add cannabinoids to that target list if regulations change.
The press release states the interface should allow users to reduce the number of steps needed in the analysis and simplify the workflow. The instrument comes with a three-year warranty, preventative maintenance plan and lifetime technical support.
Almost as soon as cannabis became recreationally legal, the public started to ask questions about the safety of products being offered by dispensaries – especially in terms of pesticide contamination. As we can see from the multiple recalls of product there is a big problem with pesticides in cannabis that could pose a danger to consumers. While The Nerd Perspective is grounded firmly in science and fact, the purpose of this column is to share my insights into the cannabis industry based on my years of experience with multiple regulated industries with the goal of helping the cannabis industry mature using lessons learned from other established markets. In this article, we’ll take a look at some unique challenges facing cannabis testing labs, what they’re doing to respond to the challenges, and how that can affect the cannabis industry as a whole.
The Big Challenge
Over the past several years, laboratories have quickly ‘grown up’ in terms of technology and expertise, improving their methods for pesticide detection to improve data quality and lower detection limits, which ultimately ensures a safer product by improving identification of contaminated product. But even though cannabis laboratories are maturing, they’re maturing in an environment far different than labs from regulated industry, like food laboratories. Food safety testing laboratories have been governmentally regulated and funded from almost the very beginning, allowing them some financial breathing room to set up their operation, and ensuring they won’t be penalized for failing samples. In contrast, testing fees for cannabis labs are paid for by growers and producers – many of whom are just starting their own business and short of cash. This creates fierce competition between cannabis laboratories in terms of testing cost and turnaround time. One similarity that the cannabis industry shares with the food industry is consumer and regulatory demand for safe product. This demand requires laboratories to invest in instrumentation and personnel to ensure generation of quality data. In short, the two major demands placed on cannabis laboratories are low cost and scientific excellence. As a chemist with years of experience, scientific excellence isn’t cheap, thus cannabis laboratories are stuck between a rock and a hard place and are feeling the squeeze.
Responding to the Challenge
One way for high-quality laboratories to win business is to tout their investment in technology and the sophistication of their methods; they’re selling their science, a practice I stand behind completely. However, due to the fierce competition between labs, some laboratories have oversold their science by using terms like ‘lethal’ or ‘toxic’ juxtaposed with vague statements regarding the discovery of pesticides in cannabis using the highly technical methods that they offer. This juxtaposition can then be reinforced by overstating the importance of ultra-low detection levels outside of any regulatory context. For example, a claim stating that detecting pesticides at the parts per trillion level (ppt) will better ensure consumer safety than methods run by other labs that only detect pesticides at concentrations at parts per billion (ppb) concentrations is a potentially dangerous claim in that it could cause future problems for the cannabis industry as a whole. In short, while accurately identifying contaminated samples versus clean samples is indeed a good thing, sometimes less isn’t more, bringing us to the second half of the title of this article.
Less isn’t always more…
In my last article, I illustrated the concept of the trace concentrations laboratories detect, finishing up with putting the concept of ppb into perspective. I wasn’t even going to try to illustrate parts per trillion. Parts per trillion is one thousand times less concentrated than parts per billion. To put ppt into perspective, we can’t work with water like I did in my previous article; we have to channel Neil deGrasse Tyson.
The Milky Way galaxy contains about 100 billion stars, and our sun is one of them. Our lonely sun, in the vastness of our galaxy, where light itself takes 100,000 years to traverse, represents a concentration of 10 ppt. On the surface, detecting galactically-low levels of contaminants sounds wonderful. Pesticides are indeed lethal chemicals, and their byproducts are often lethal or carcinogenic as well. From the consumer perspective, we want everything we put in our bodies free of harmful chemicals. Looking at consumer products from The Nerd Perspective, however, the previous sentence changes quite a bit. To be clear, nobody – nerds included – wants food or medicine that will poison them. But let’s explore the gap between ‘poison’ and ‘reality’, and why that gap matters.
In reality, according to a study conducted by the FDA in 2011, roughly 37.5% of the food we consume every day – including meat, fish, and grains – is contaminated with pesticides. Is that a good thing? No, of course it isn’t. It’s not ideal to put anything into our bodies that has been contaminated with the byproducts of human habitation. However, the FDA, EPA, and other governmental agencies have worked for decades on toxicological, ecological, and environmental studies devoted to determining what levels of these toxic chemicals actually have the potential to cause harm to humans. Rather than discuss whether or not any level is acceptable, let’s take it on principle that we won’t drop over dead from a lethal dose of pesticides after eating a salad and instead take a look at the levels the FDA deem ‘acceptable’ for food products. In their 2011 study, the FDA states that “Tolerance levels generally range from 0.1 to 50 parts per million (ppm). Residues present at 0.01 ppm and above are usually measurable; however, for individual pesticides, this limit may range from 0.005 to 1 ppm.” Putting those terms into parts per trillion means that most tolerable levels range from 100,000 to 50,000,000 ppt and the lower limit of ‘usually measurable’ is 10,000 ppt. For the food we eat and feed to our children, levels in parts per trillion are not even discussed because they’re not relevant.
A specific example of this is arsenic. Everyone knows arsenic is very toxic. However, trace levels of arsenic naturally occur in the environment, and until 2004, arsenic was widely used to protect pressure-treated wood from termite damage. Because of the use of arsenic on wood and other arsenic containing pesticides, much of our soil and water now contains some arsenic, which ends up in apples and other produce. These apples get turned into juice, which is freely given to toddlers everywhere. Why, then, has there not an infant mortality catastrophe? Because even though the arsenic was there (and still is), it wasn’t present at levels that were harmful. In 2013, the FDA published draft guidance stating that the permissible level of arsenic in apple juice was 10 parts per billion (ppb) – 10,000 parts per trillion. None of us would think twice about offering apple juice to our child, and we don’t have to…because the dose makes the poison.
How Does This Relate to the Cannabis Industry?
The concept of permissible exposure levels (a.k.a. maximum residue limits) is an important concept that’s understood by laboratories, but is not always considered by the public and the regulators tasked with ensuring cannabis consumer safety. As scientists, it is our job not to misrepresent the impact of our methods or the danger of cannabis contaminants. We cannot understate the danger of these toxins, nor should we overstate their danger. In overstating the danger of these toxins, we indirectly pressure regulators to establish ridiculously low limits for contaminants. Lower limits always require the use of newer testing technologies, higher levels of technical expertise, and more complicated methods. All of this translates to increased testing costs – costs that are then passed on to growers, producers, and consumers. I don’t envy the regulators in the cannabis industry. Like the labs in the cannabis industry, they’re also stuck between a rock and a hard place: stuck between consumers demanding a safe product and producers demanding low-cost testing. As scientists, let’s help them out by focusing our discussion on the real consumer safety issues that are present in this market.
*average of domestic food (39.5% contaminated) and imported food (35.5% contaminated)
Election Day 2016 resulted in historic gains for state level cannabis prohibition reform. Voters in California, Maine, Massachusetts and Nevada chose to legalize adult use of Cannabis sp. and its extracts while even traditionally conservative states like Arkansas, Florida, Montana and North Dakota enacted policy allowing for medical use. More than half of the United States now allows for some form of legal cannabis use, highlighting the rapidly growing need for high quality analytical testing.
For the uninitiated, analytical instrumentation can be a confusing mix of abbreviations and hyphenation that provides little obvious information about an instrument’s capability, advantages and disadvantages. In this series of articles, my colleagues and I at Restek will break down and explain in practical terms what instruments are appropriate for a particular analysis and what to consider when choosing an instrumental technique.
Potency analysis refers to the quantitation of the major cannabinoids present in Cannabis sp. These compounds are known to provide the physiological effects of cannabis and their levels can vary dramatically based on cultivation practices, product storage conditions and extraction practices.
The primary technique is high performance liquid chromatography (HPLC) coupled to ultraviolet absorbance (UV) detection. Gas chromatography (GC) coupled to a flame ionization detector (FID) or mass spectrometry (MS) can provide potency information but suffers from issues that preclude its use for comprehensive analysis.
Pesticide Residue Analysis
Pesticide residue analysis is, by a wide margin, the most technically challenging testing that we will discuss here. Trace levels of pesticides incurred during cultivation can be transferred to the consumer both on dried plant material and in extracts prepared from the contaminated material. These compounds can be acutely toxic and are generally regulated at part per billion parts-per-billion levels (PPB).
Depending on the desired target pesticides and detection limits, HPLC and/or GC coupled with tandem mass spectrometry (MS/MS) or high resolution accurate mass spectrometry (HRAM) is strongly recommended. Tandem and HRAM mass spectrometry instrumentation is expensive, but in this case it is crucial and will save untold frustration during method development.
Residual Solvents Analysis
When extracts are produced from plant material using organic solvents such as butane, alcohols or supercritical carbon dioxide there is a potential for the solvent and any other contaminants present in it to become trapped in the extract. The goal of residual solvent analysis is to detect and quantify solvents that may remain in the finished extract.
Residual solvent analysis is best accomplished using GC coupled to a headspace sample introduction system (HS-GC) along with FID or MS detection. Solid phase microextraction (SPME) of the sample headspace with direct introduction to the GC is another option.
Terpene Profile Analysis
While terpene profiles are not a safety issue, they provide much of the smell and taste experience of cannabis and are postulated to synergize with the physiologically active components. Breeders of Cannabis sp. are often interested in producing strains with specific terpene profiles through selective breeding techniques.
Both GC and HPLC can be employed successfully for terpenes analysis. Mass spectrometry is suitable for detection as well as GC-FID and HPLC-UV.
Heavy Metals Analysis
Metals such as arsenic, lead, cadmium, chromium and mercury can be present in cannabis plant material due to uptake from the soil, fertilizers or hydroponic media by a growing plant. Rapidly growing plants like Cannabis sp. are particularly efficient at extracting and accumulating metals from their environment.
Several different types of instrumentation can be used for metals analysis, but the dominant technology is inductively coupled plasma mass spectrometry (ICP-MS). Other approaches can also be used including ICP coupled with optical emission spectroscopy (ICP-OES).
Rebecca is an Applications Scientist at Restek Corporation and is eager to field any questions or comments on cannabis analysis, she can be reached by e-mail, email@example.com or by phone at 814-353-1300 (ext. 2154)
Dr. Zacariah Hildenbrand, chief scientific officer and partner at C4 Laboratories, is currently researching some of the lesser-known molecules in cannabis, and he’s on to something. His research focuses on discovering new molecules, determining their therapeutic effects and expanding our understanding of the constituents of cannabis.
Dr. Hildenbrand received his Ph.D. from the University of Texas at El Paso where he researched the molecular architecture involved in hormone-dependent cancers. At the University of Texas Southwestern Medical Center in Dallas, his post-doctoral research contributed to the development of a novel therapy for the treatment of chronic myeloid leukemia, a blood-borne cancer that afflicts small children. He has published over 25 peer-reviewed scientific journal articles and hopes to do the same with his research in cannabis.
After a career of scientific consulting, Dr. Hildenbrand met Ryan Treacy, founder and chief executive officer of C4 Laboratories, in 2015 when Treacy launched the company. In June of 2015, the laboratory began operations, providing Dr. Hildenbrand the opportunity to embark on a new and exciting field of research- cannabis.
They currently collaborate with Dr. Kevin Schug of the Shimadzu Center for Advanced Analytical Chemistry (SCAAC) at the University of Texas, Arlington and together Drs. Schug and Hildenbrand are pursuing a DEA license to expand their current cannabis research. The SCAAC is a $10.0+ million analytical laboratory with instrumentation that only a handful of people in the world has access to.
C4 Laboratories, based in Mesa, Arizona, currently offers a range of services for cannabis analysis including terpene and cannabinoid analytics, microbial, pesticide, fungicide and insecticide testing. In addition to the standard gamut of tests, they also specialize in cultivation analytics like mold and mildew culture testing, viral detection with sentinel plants and comprehensive analysis of environmental conditions.
What makes their company unique is their multidisciplinary effort to characterize the therapeutic compounds found in cannabis, the C4 Cannabinomics Collaborative. We sit down with Dr. Zac Hildenbrand to talk cannabis science, his research and what they hope to accomplish with the C4 Cannabinomics Collaborative.
CannabisIndustryJournal: What is the C4 Cannabinomics Collaborative?
Dr. Zacariah Hildenbrand: The C4 Cannabinomics Collaborative is an open collaboration between growers and scientists to discover new molecules in cannabis and to have a better characterization of individual cannabis strains based on the active constituents found in each sample. We are facilitating the collaboration of some of the world’s best cannabis growers with world-class scientists to find new information about the plant.
What we want to accomplish in this work is identifying novel molecules. Because of the [federal government’s] restrictions in researching cannabis, there is very little peer-reviewed literature on many of the compounds found in cannabis. We want to secondarily find out what those molecules do in the human body and thus make recommendations for strains targeting specific conditions.
We also want to understand the strains currently out there by determining the most established cannabinoids and terpenes via chemotyping. You hear a lot of people talking about the effects of an Indica or Sativa and making recommendations based on that. We want to find chemical signatures based on cannabinoids and terpenes and make recommendations based on that. There are a lot of problems at hand when discussing strain names scientifically. There are nomenclature issues- people calling the same strain different names, people giving multiple names to the same strain to make it appear that their strain portfolios are more diverse.
We can identify the chemical signatures in strains based on the major cannabinoids and terpenes. Based on the terpenes and chemical profile we can determine more accurate recommendations for patients as well as in recreational applications. All of this, again, discovering the new molecules, identifying the current strains, is so we can make more informed decisions regarding cannabis use. It is not a panacea but it is a very robust plant. There are a lot of terpenes with anti-inflammatory responses. Other molecules help with blood flow, sleep, regulating blood glucose, and we all know the cases of CBD helping children with convulsions and epilepsy. We want people to make sure they have the most up-to-date information.
CIJ: How is your collaboration with the SCAAC at UT Arlington contributing to this work?
Dr. Hildenbrand: One of the instruments we use there is a supercritical-fluid-extraction supercritical-fluid-chromatography mass-spectrometer (SFE-SFC-MS). With that instrument, we can do the extraction on the machine with an extreme level of sensitivity. It is ideal for drug discovery and identifying molecules in the parts-per-quadrillion range. This particular instrument allows us to detect molecules with an extreme level of sensitivity without volatizing them during the sample extraction process.
We want to acquire samples of unique cannabis from growers that will work with us to discover new cannabis constituents. We are in the process of getting a DEA license so that we can send products across state lines to the center at UT Arlington to perform the advanced characterization. They have instrumentation that only a handful of people in the world have access to, which gives us the best opportunity to explore the unknown. When we discover new molecules, find out what they do on the molecular level, we can then isolate these compounds and ultimately use this newfound knowledge for the development of effective nutraceuticals.
CIJ: What molecules are you researching right now?
Dr. Hildenbrand: Some of the low-hanging fruit in our research looks at identifying compounds similar to the better-studied compounds such as THC and CBD. THCV has a very similar structure to THC, but has a shorter acyl carbon chain (3 carbons vs. 5).
THCV doesn’t induce a psychoactive response (like THC), but it does improve fat utilization, so it has remarkable potential for medicine. We are looking at what conditions are required for it to occur naturally. Cannabis doesn’t produce THCV in a high amount. 0.7% by weight is the most we have seen in Arizona. In Oregon, where craft cannabis has been refined to a much higher degree, we have heard rumblings of some strains containing up to 3% THCV. We want to find out if this is a possible weight loss tool. Our research in CBDV is very much the same.
CBL is the breakdown product of CBC when it is treated with ultraviolet light. We know absolutely nothing about what CBL does. If we find a strain that produces high amounts of CBC, we can then treat it with UV light and force the conversion to CBL, and then ultimately determine what it does. This is a good example of low-hanging fruit and the versatility of cannabis. Based on the biogenesis of the cannabinoids, we can alter the profile of cannabis products using a series of biochemical reactions.
For example, we have been helping clients in Arizona look for a quality sleep aid in cannabis. Certainly, Indica strains will help, but the molecule CBN helps specifically with sleep abnormalities. As CBN is formed as a byproduct when CBD or THC are oxidized, we see some producers using liquid nitrogen to oxidize CBD, leading to higher CBN levels. I would like to think we are in the age of understanding CBD, THC and the major terpenes,but there are a whole milieu of compounds that require our attention and THCV, CBDV and CBL are just a few that we want to devote our efforts to right away.
CIJ: What are your plans in the immediate future?
Dr. Hildenbrand: We are in the process of finalizing the documents to bring a C4 laboratory into Oregon where we can do quite a bit of research and where we’ll have access to some very unique cannabis. We will offer full compliance testing per ORELAP and OLCC regulations, but we also want to acquire samples (free of charge) from growers that want to collaborate with us to discover new molecules. We’ve been lucky enough to start working with growers like Adam Jacques and Chris West in Eugene, but we also want to be available to other growers who want to contribute to this research.
CIJ: What are your long-term goals with this project?
Dr. Hildenbrand: At a basic level, we hope to expand the current understanding of the cannabis plant. There is a lot of “bro science” and anecdotal claims out there. There is so much that we don’t know about cannabis that we cannot simply rely on anecdotal claims for each strain. We want to bring cannabis into the same light as any pharmaceutical-grade or biomedical research.
We need to be characterizing this plant with the same level of detail as other pertinent molecular therapies. In doing so there are a lot of potential discoveries to be made and we might be able to unlock the future of medicine. A drug like Marinol, for example, has been met with mixed reviews because its only one dimensional. Furthermore, we find that the terpene molecules are tremendously beneficial and this interplay between cannabinoids and terpenes is something that we want to explore further. All and all we wish to further illustrate the therapeutic capacities of cannabis within the contexts of specific ailments and medical conditions, while discovering the medicine of the future.
In my last column, I took a refreshing step out of the weeds of the specifics behind cannabis analyses and took a broader, less technical look at the cannabis industry. I had envisioned The Nerd Perspective being filled with profound insights that I have had in the cannabis industry, but I have realized that if I restricted this column to insights most would consider profound…well…there would not be many articles. So in this article, I want to share an insight with you, but not one that is earth shattering. Instead, I want to talk about a simple concept in a way that might help you think a little differently about the results your lab generates, the results you have to pay for or even the results printed on a cannabis product you might purchase.
This article is all about the simple concept of concentration – the expression of how much of something there is in relation to something else. We use expressions of concentration all the time – calories per serving, percent alcohol in beer, even poll results in the presidential election circus. Cannabis is not excluded from our flippant use of concentration terms – percent cannabinoid content, parts-per-million (ppm) residual solvents, and parts-per-billion (ppb) pesticides. Most of us know the definition of percent, ppm, and ppb, and we use these terms all the time when discussing cannabis analytical methods. During my career in analytical chemistry, it has occurred to me that parts per billion is a really infinitesimal amount…I know that intellectually, but I have never tried to actually visualize it. So being the nerd that I am, I went about comparing these often-used concentration terms visually in my kitchen.
I started by preparing a 1% solution of food coloring paste in water. This was accomplished by weighing out 5g of the food coloring and dissolving it into 500mL of water (about one teaspoon into a pint). The resulting solution was so dark it was almost black:
The picture above expresses the low end of what we care about in terms of cannabinoid concentration and a pretty normal value for a high-concentration terpene in cannabis.
I then took one teaspoon of that mixture and dissolved it into 1.32 gallons of water (5mL into 5000mL), resulting in a 10ppm solution of green food coloring in water:
I did not expect the resulting solution to be so light colored given the almost-black starting solution, but I did dilute the solution one thousand times. To put this into perspective, 10ppm is well above many state regulatory levels for benzene in a cannabis concentrate.
I then took one teaspoon of the almost-colorless 10ppm solution and dissolved that into another 1.32 gallons of water, resulting in a very boring-looking 10ppb solution of green food coloring in water:
Obviously, since I diluted the almost-colorless 10ppm solution a thousand times, the green food coloring cannot be seen in the picture above. As a reference, 10ppb is on the low end of some regulations for pesticides in food matrices, including – possibly – cannabis. I know the above picture is not really very compelling, so let’s think in terms of mass. The picture above shows eleven pounds of water. That eleven pounds of water contains 50 micrograms of food coloring…the weight of a single grain of sand.
To expand on the mass idea, let’s take a look at the total mass of cannabis sold legally in Colorado in 2015 – all 251,469 pounds of it. To express just how staggeringly small the figure of 10ppb is, if we assume that all of that cannabis was contaminated with 10ppb of abamectin, the total mass of abamectin in that huge amount of cannabis would be just 1.143g – less than half the mass of a penny.
To me, that is an extremely compelling picture. The fact is there are instruments available that can measure such infinitesimal concentrations. What’s more, these tiny concentrations can be measured in the presence of relatively massive amounts of other compounds – cannabinoids, terpenes, sugars, fats – that are always present in any given cannabis sample. The point I’d like to make is that the accurate measurement of trace amounts of cannabis contaminants including pesticides and residual solvents is an astounding feat that borders on magical. This feat is not magic though. It requires extremely delicate instrumentation, ultra-pure reagents, expert analysts, and labor-intensive sample preparation. It is far from trivial, and unlike magic, requires a large investment on the part of the laboratories performing this feat of science. Other industries have embraced this reality, and the cannabis industry is well on its way toward that end…hopefully this article will help put the job of the cannabis analytical lab into perspective.
This is the first piece of a regular column that CIJ has been so kind to allow me to write for their publication. Some readers might recognize my name from The Practical Chemist column in this publication. Since the inception of that column, I’ve finally taken the plunge into the cannabis industry as chief technical officer of Emerald Scientific. Unlike The Practical Chemist, I will not spend the entire first article introducing the column. The concept is simple: while I find the textbook-esque content of The Practical Chemist scintillating, I have a feeling that the content is a little too heavy to spring on someone who is looking for engaging articles over their precious coffee break. Instead, The Nerd Perspective will consist of less-technical writing focusing on my experience and insights for the cannabis industry as a whole. But don’t worry – I’m sure I will not be able to refrain from technical jargon altogether.
To kick off the column, I want to talk about instrumentation for ‘instant’ cannabis potency testing. At this point, it’s common knowledge in the cannabis analytics industry that the most accurate way to test cannabis potency is through extraction then analysis by HPLC-UV. I agree wholeheartedly with that sentiment, but HPLC analyses have one drawback: they can be either inexpensive or fast – not both. There are some instruments entering the market now that– while not as directly quantitative as HPLC-UV – promise to solve the inexpensive/fast conundrum. During my most recent trip to California, I was able to spend some quality time with two well-known instrument manufacturers: SRI Instruments and PerkinElmer, both of whom manufacture instruments that perform fast, inexpensive cannabis potency analyses. From my previous home at the heights of The Ivory Tower of Chromatography: Home of the Application Chemists, SRI and PE couldn’t be more different. But as seen through the eyes of a company who deals with a wide range of customers and analytical needs, it turns out that SRI and PE are much the same – not only in their open and honest support of the cannabis industry, but also in terms of their love of all things technical.
My first stop was SRI Instruments. They are a relatively small company located in an unassuming building in Torrance, CA. Only a few people work in that location, and I spent my time with Hugh Goldsmith (chief executive officer) and Greg Benedict (tech service guru). I have worked with these guys for a few years now, and since the beginning, I have lovingly referred to them as the MacGyvers of chromatography. Anyone familiar with SRI GCs knows that what they lack in aesthetics, they make up for in practicality – these instruments truly reflect Hugh and Greg’s character (that’s meant as a compliment).
SRI specializes in relatively inexpensive portable and semi-portable instruments that are easy to set up, easy to operate, and most importantly – engineered for a purpose. It’s actually really hard to manufacture an instrument that meets all three of these criteria, and the folks at SRI accomplish this with their passionate and unique approach to problem solving. What I love about these guys is that for them, nothing is impossible. Here’s an example: the price of the portable GC-FID instruments SRI builds is inflated because the instruments require separate – and pricey – hydrogen generators. That’s a big problem – hydrogen generators are all pretty much the same, and none of them are cheap. This didn’t faze SRI: they just decided to design their own super small on-board hydrogen generator capable of supplying hydrogen to a simple GC system for six hours with just 20mL of distilled water from the grocery store! I’m not kidding – I saw it in action on their new Model 420 GC (more on that in some future pieces). Was the final product pretty? Not in the least. Did it work? Absolutely. This kind of MacGyver-esque problem solving can only be done successfully with a deep understanding of the core principles behind the problem. What’s more, in order to engineer instruments like these, SRI has to have mastery over the core principles of not only chromatographic separation, but also of software development, electrical engineering, and mechanical engineering – just to name a few. These quirky, unassuming guys are smart. SRI is a company that’s been unapologetically true to themselves for decades; they’ll never be a contender for beauty queen, but they get the job done.
On the surface, PerkinElmer (PE) contrasts with SRI in almost every way possible. With revenue measured in billions of dollars and employees numbering in the thousands, PE is a behemoth that plays not only in the analytical chemistry industry but also in clinical diagnostics and other large industries. Where SRI instruments have a characteristic look of familiar homeliness, PE instruments are sleek and sexy. However, PerkinElmer and SRI are more alike than it would seem; just like the no-frills SRI, the hyper-technical PE instruments are engineered for a purpose by teams of very smart, passionate people.
With its modest price tag and manual sample introduction, the SRI Model 420 is engineered for lower throughput users to be a fast, simple, and inexpensive approach to semi-quantitative process control. The purpose of the instruments manufactured by PE is to produce the highest-quality quantitative results as quickly as possible for high-throughput labs. PE instruments are built using the best technology available in order to eke out every last ounce of quantitative accuracy and throughput possible. Fancy technology is rarely inexpensive, and neither is rigorous product development that can last years in some cases. In a way, PE is Doogie Howser to SRI’s MacGyver. Like MacGyver, Doogie is super smart, and his setting is a sterile hospital rather than a warzone.
I had a wonderful conversation with Tim Ruppel, PE’s headspace-GC specialist, on the sample introduction technology incorporated into the TurboMatrix Headspace Sampler, where I also learned that the basic technology for all PerkinElmer headspace-GC instruments was designed by the men who wrote The Book on headspace gas chromatography: Bruno Kolb and Leslie Ettre**. Later, I was able to get a much-needed lesson on FT-IR and the Spectrum Two IR Spectrometer from Brian Smith, PE’s spectroscopy expert, who actually wrote the book on quantitative spectroscopy***. Tim and Brian’s excitement over their technology mirrored that of Hugh and Greg. It turns out that SRI and PerkinElmer are more alike than I thought.
These two instrument manufacturers have addressed the fast/inexpensive conundrum of cannabis potency testing in two different ways: SRI’s instrument is extremely inexpensive, easy to operate, and will provide semi-quantitative values for THC, CBD, and CBN in just a few minutes; PE’s instrument is more expensive up front, but provides quantitative (though not directly quantitative) values for all of the major cannabinoids almost instantly, and requires almost no maintenance or consumables. These two instruments were designed for specific uses: one for inexpensive, easy use, and the other for more comprehensive results with a higher initial investment. The question consumers have to ask themselves is “Who do I need to solve my problem?” For some, the answer will be MacGyver, and for others, Doogie Howser will provide the solution – after all, both are heroes.
** B. Kolb, L. Ettre, Static Headspace-Gas Chromatography: Theory and Practice, John Wiley & Sons, Hoboken, NJ, 2006.
*** Brian C. Smith, Quantitative Spectroscopy: Theory and Practice, Elsevier, Boston, MA, 2002.