Tag Archives: butane

Chris English
The Practical Chemist

Accurate Detection of Residual Solvents in Cannabis Concentrates

By Chris English
No Comments
Chris English

Edibles and vape pens are rapidly becoming a sizable portion of the cannabis industry as various methods of consumption popularize beyond just smoking dried flower. These products are produced using cannabis concentrates, which come in the form of oils, waxes or shatter (figure 1). Once the cannabinoids and terpenes are removed from the plant material using solvents, the solvent is evaporated leaving behind the product. Extraction solvents are difficult to remove in the low percent range so the final product is tested to ensure leftover solvents are at safe levels. While carbon dioxide and butane are most commonly used, consumer concern over other more toxic residual solvents has led to regulation of acceptable limits. For instance, in Colorado the Department of Public Health and Environment (CDPHE) updated the state’s acceptable limits of residual solvents on January 1st, 2017.

Headspace Analysis

Figure 1: Shatter can be melted and dissolved in a high molecular weight solvent for headspace analysis (HS). Photo Courtesy of Cal-Green Solutions.

Since the most suitable solvents are volatile, these compounds are not amenable to HPLC methods and are best suited to gas chromatography (GC) using a thick stationary phase capable of adequate retention and resolution of butanes from other target compounds. Headspace (HS) is the most common analytical technique for efficiently removing the residual solvents from the complex cannabis extract matrix. Concentrates are weighed out into a headspace vial and are dissolved in a high molecular weight solvent such as dimethylformamide (DMF) or 1,3-dimethyl-3-imidazolidinone (DMI). The sealed headspace vial is heated until a stable equilibrium between the gas phase and the liquid phase occurs inside the vial. One milliliter of gas is transferred from the vial to the gas chromatograph for analysis. Another approach is full evaporation technique (FET), which involves a small amount of sample sealed in a headspace vial creating a single-phase gas system. More work is required to validate this technique as a quantitative method.

Gas Chromatographic Detectors

The flame ionization detector (FID) is selective because it only responds to materials that ionize in an air/hydrogen flame, however, this condition covers a broad range of compounds. When an organic compound enters the flame; the large increase in ions produced is measured as a positive signal. Since the response is proportional to the number of carbon atoms introduced into the flame, an FID is considered a quantitative counter of carbon atoms burned. There are a variety of advantages to using this detector such as, ease of use, stability, and the largest linear dynamic range of the commonly available GC detectors. The FID covers a calibration of nearly 5 orders of magnitude. FIDs are inexpensive to purchase and to operate. Maintenance is generally no more complex than changing jets and ensuring proper gas flows to the detector. Because of the stability of this detector internal standards are not required and sensitivity is adequate for meeting the acceptable reporting limits. However, FID is unable to confirm compounds and identification is only based on retention time. Early eluting analytes have a higher probability of interferences from matrix (Figure 2).

Figure 2: Resolution of early eluting compounds by headspace – flame ionization detection (HS-FID). Chromatogram Courtesy of Trace Analytics.

Mass Spectrometry (MS) provides unique spectral information for accurately identifying components eluting from the capillary column. As a compound exits the column it collides with high-energy electrons destabilizing the valence shell electrons of the analyte and it is broken into structurally significant charged fragments. These fragments are separated by their mass-to-charge ratios in the analyzer to produce a spectral pattern unique to the compound. To confirm the identity of the compound the spectral fingerprint is matched to a library of known spectra. Using the spectral patterns the appropriate masses for quantification can be chosen. Compounds with higher molecular weight fragments are easier to detect and identify for instance benzene (m/z 78), toluene (m/z 91) and the xylenes (m/z 106), whereas low mass fragments such as propane (m/z 29), methanol (m/z 31) and butane (m/z 43) are more difficult and may elute with matrix that matches these ions. Several disadvantages of mass spectrometers are the cost of equipment, cost to operate and complexity. In addition, these detectors are less stable and require an internal standard and have a limited dynamic range, which can lead to compound saturation.

Regardless of your method of detection, optimized HS and GC conditions are essential to properly resolve your target analytes and achieve the required detection limits. While MS may differentiate overlapping peaks the chances of interference of low molecular weight fragments necessitates resolution of target analytes chromatographically. FID requires excellent resolution for accurate identification and quantification.

Cannabusiness Sustainability

Dear Cannabusiness Community

By Olivia L. Dubreuil, Esq., Brett Giddings

Dear Cannabusiness Community,

You may have read our two recent articles. We received so much positive feedback that Aaron Biros (editor-in-chief of Cannabis Industry Journal) has invited us to continue with our own column at CannabisIndustryJournal.com. We are very happy to launch this column, and we thought we would take this opportunity to introduce our project, our vision and ourselves so you can understand where we are coming from when you read this series of articles.

Brett and I both have a background in business sustainability and corporate responsibility. We both have backgrounds in management consulting, with a specific expertise in sustainability issues along the supply chain. We have been working together for almost nine months now on sustainability issues in the Bay Area. In May, we started to get interested in sustainability in the cannabis industry and before we knew it we were diving deep into research relating to the environmental, social and ethical impacts of the legal cannabis industry. It was actually difficult to find a lot of information, as the reign of prohibition still very much influences what is available.cannabusiness

In June, we attended the National Cannabis Industry Association’s conference in Oakland to open up the conversation with cannabis industry players and to find out about people’s attitudes and approach to sustainability. The results were overwhelmingly positive. Not only were we encouraged to launch a project, but also excited to discover that many of the speakers presenting at the conference referenced sustainability in one way or another when they talked about environmental impact awareness, social justice, ethics or about staying competitive when “big business” enters the market.

What started out as a side project quickly became the center of focus this summer when we decided to incorporate Project Polaris, a California non-profit, to deliver sustainability knowledge and expertise to the cannabis industry.

Our thinking is as follows:

Thinking about sustainability, means thinking strategically about business. As we forge a new and upcoming industry, let’s seize the opportunity to make it a sustainability-focused one! Let’s create generally accepted industry principles that fosters a positive image of the industry and teaches newcomers about best environmental and social practices. Let’s create a voluntary and industry-led socially responsible code of conduct for cannabis business owners and suppliers, helping the regulators, as they will be drafting all of the future regulations of the legalized cannabis market. Let’s do more research on the market and the consumer. Let’s develop clean and green alternatives to dirty processes or practices. Let’s elevate the discussion and create a model industry, one where short-term, large-scale, quality-lowering corporate interests are kept at bay.

With this vision in mind, we created Project Polaris because we believe that this is a real opportunity for the industry to be a role model for other industries (and educate legislators as well as drive public opinion in those states that are still under prohibition laws). We believe there is a real economic opportunity for those businesses that understand how to embed sustainability properly within their business model. Because we know that sustainability influences legislators in a positive way because it sheds a positive light on businesses.

In the upcoming months, we will continue to research and report on sustainability-related issues facing the cannabis industry, such as packaging, edibles, “organic” in cannabis, butane extraction versus CO2 extraction and so on. We also welcome questions from our readers. If you have a question, please post it in the comments section below.

We will also take this opportunity to call out to cannabis industry organizations, cannabis businesses, or cannabis related services and product suppliers to get in touch with us if they wish to find out how to integrate sustainability more concretely into their action plan. We are not planning on doing this alone, we are seeking partners to join us on this journey, and we want to partner with you on your journey to Cannabusiness Sustainability.

PS: We still have one seat open for the board of directors and would love to hear from you if you are interested!

AOCS Highlights Cannabis Lab Standards, Extraction Technology

By Aaron G. Biros
No Comments

The American Oil Chemists’ Society (AOCS) held its annual conference in Salt Lake City this week, with a track focused on cannabis testing and technology. Cynthia Ludwig, director of technical services at AOCS and member of the advisory panel to The Emerald Test, hosted the two-day event dedicated to all things extraction technology and analytical testing of cannabis.

Highlights in the discussion surrounding extraction technologies for the production of cannabis concentrates included the diversity of concentrate products, solvent selection for different extraction techniques and the need for cleaning validation in extraction equipment. Jerry King, Ph.D., research professor at the University of Arkansas, began the event with a brief history of cannabis processing, describing the physical morphologies in different types of extraction processes.

J. Michael McCutcheon presents a history of cannabis in medicine
J. Michael McCutcheon presents a history of cannabis in medicine

Michael McCutcheon, research scientist at Eden Labs, laid out a broad comparison of different extraction techniques and solvents in use currently. “Butane is a great solvent; it’s extremely effective at extracting active compounds from cannabis, but it poses considerable health, safety and environmental concerns largely due to its flammability,” says McCutcheon. He noted it is also very difficult to get USP-grade butane solvents so the quality can be lacking. “As a solvent, supercritical carbon dioxide can be better because it is nontoxic, nonflammable, readily available, inexpensive and much safer.” The major benefit of using supercritical carbon dioxide, according to McCutcheon, is its ability for fine-tuning, allowing the extractor to be more selective and produce a wider range of product types. “By changing the temperature or pressure, we can change the density of the solvent and thus the solubility of the many different compounds in cannabis.” He also noted that, supercritical carbon dioxide exerts tremendous pressure, as compared to hydrocarbon solvents, so the extraction equipment needs to be rated to a higher working pressure and is generally more expensive.

John A. Mackay, Ph.D., left at the podium and Jerry King, Ph.D., on the right
John A. Mackay, Ph.D., left at the podium and Jerry King, Ph.D., on the right

John A. Mackay, Ph.D., senior director of strategic technologies at Waters Corporation, believes that cannabis processors using extraction equipment need to implement cleaning SOPs to prevent contamination. “There is currently nothing in the cannabis industry like the FDA CMC draft for the botanical industry,” says Mackay. “If you are giving a child a high-CBD extract and it was produced in equipment that was previously used for another strain that contains other compounds, such as CBG, CBD or even traces of THC extract, there is a high probability that it will still contain these compounds as well as possibly other contaminants unless it was properly cleaned.” Mackay’s discussion highlighted the importance of safety and health for workers throughout the workflow as well as the end consumer.

Jeffrey Raber, Ph.D., chief executive officer of The Werc Shop, examined different testing methodologies for different applications, including potency analyses with liquid chromatography. His presentation was markedly unique in proposing a solution to the currently inconsistent classification system for cannabis strains. “We really do not know what strains cause what physiological responses,” says Raber. “We need a better classification system based on chemical fingerprints, not on baseless names.” Raber suggests using a chemotaxonomic system to identify physiological responses in strains, noting that terpenes could be the key to these responses.

Cynthia Ludwig welcomes attendees to the event.
Cynthia Ludwig welcomes attendees to the event.

Dylan Wilks, chief scientific officer at Orange Photonics, discussed the various needs in sample preparation for a wide range of products. He focused on sample prep and variation for on-site potency analysis, which could give edibles manufacturers crucial quality assurance tools in process control. Susan Audino, Ph.D., chemist and A2LA assessor, echoed Wilks’ concerns over sample collection methods. “Sampling can be the most critical part of the analysis and the sample size needs to be representative of the batch, which is currently a major issue in the cannabis industry,” says Audino. “I believe that the consumer has a right to know that what they are ingesting is safe.” Many seemed to share her sentiment about the current state of the cannabis testing industry. “Inadequate testing is worse than no testing at all and we need to educate the legislators about the importance of consumer safety.”

46 cannabis laboratories participated in The Emerald Test’s latest round of proficiency testing for potency and residual solvents. Cynthia Ludwig sits on the advisory panel to give direction and industry insights, addressing specific needs for cannabis laboratories. Kirsten Blake, director of sales at Emerald Scientific, believes that proficiency testing is the first step in bringing consistency to cannabis analytics. “The goal is to create some level of industry standards for testing,” says Blake. Participants in the program will be given data sets, judged by a consensus mean, so labs can see their score compared to the rest of the cannabis testing industry. Proficiency tests like The Emerald Test give labs the ability to view how consistent their results are compared to the industry’s results overall. According to Ludwig, the results were pleasantly surprising. “The results were better than expected across the board; the vast majority of labs were within the acceptable range,” says Ludwig. The test is anonymous so individual labs can participate freely.

The AOCS cannabis working groups and expert panels are collaborating with Emerald Scientific to provide data analytics reports compliant with ISO 13528. “In the absence of a federal program, we are trying to provide consistency in cannabis testing to protect consumer safety,” says Ludwig. At the AOCS annual meeting, many echoed those concerns of consumer safety, proposing solutions to the current inconsistencies in testing standards.

BEST Extractions

Busting the Myth: Examining CO2 versus Butane Extraction

By John A. Mackay, Ph. D.

The basis of anecdotal controversy continues about the use of hydrocarbons versus carbon dioxide. It is important to note that hydrocarbons span a range of phases on the planet earth.

It is important to eliminate the cost of the instruments and the cost of the facilities from this comparison to keep the discussion on specifically the extraction principles.

Source: (https://en.wikipedia.org/wiki/Butane#Isomers)
Source: (https://en.wikipedia.org/wiki/Butane#Isomers)

Butane is a gaseous hydrocarbon. As you add more carbons to hydrocarbons, they move from gaseous to liquid.

It is also important to note that the same is true of carbon dioxide in its natural form on the earth’s atmosphere, it is a gas. It is nonflammable and used in fire extinguishers.

At typical conditions, carbon dioxide in the supercritical range is similar to hexane (C6H14) and ethyl acetate in its solubility characteristics. Propane (C3H8) and butane (C4H10) are gases at normal atmospheric conditions. Both must be manipulated for the extraction of CBDA and CBD. For example, both CO2 and C4H10 must be placed under pressure and then passed through the material to extract the lipophilic terpenes and cannabinoids.

For this short discussion, let’s remove the concern about the different volatilities of the compounds. Hydrocarbons with a spark will be significantly more powerful of an explosion than carbon dioxide (note it could be used to put out the butane fire). The hydrocarbons can be in more configurations and therefore the getting the correct form initially is critical. For example, butane can have all the carbons in a row like a train, or branched like a tree. Those are very different and have different characteristics too. Getting pharmaceutical grade butane is essential to ensure safety. The concern that people have expressed with butane is what is in the other 0.1% for 99.9%. Checking for residual butane is less of a concern than the polyaromatic hydrocarbons in the untested cylinder. Furthermore, in the wrong hands it can be more volatile.

Source: (https://en.wikipedia.org/wiki/Carbon_dioxide)
Source: (https://en.wikipedia.org/wiki/Carbon_dioxide)

The critical premise that needs to be considered is the final formulation. Is one solvent significantly more applicable than the other? No. They have different characteristics.

Propane is a common solvent in the spices, flavors and fragrances industry. For example, the extraction of lipids and oils from vegetables and the fatty oils from seeds, it would be an advantage to have a solvent that is totally miscible, i.e. will be totally soluble in a fluid. This is similar to the idea of sugar in hot water versus in water in ice. If an example of cardamom were used comparing CO2 and propane (which is similar to butane), the pressure needed for CO2 would be 100 bar, while propane would be only 20 bar. However the increasing the pressure of the propane from 20 to 50 bar at a constant 25 C, also increases the chlorophyll from 3.4 g/g oil to 10.8 g/g oil. Meanwhile with the more finely tunable CO2 from 80 to 100 to 200 the amount of chlorophyll is negligible (0.36 g/g oil) but at 300 bar it dramatically increases to 4.53 g/g oil.

Additionally the CO2 is a better extraction for the terpenes in the cardamom. The beta-pinine, Cineole, linalool, alpha-terpinol and bornelole. The increase in the propane pressure will allow us to increase the yield of the CO2 (Illes, V, et. al. Proceedings of the Fifth Meeting of Supercritical Fluids, Nice, France, Tome 2, 555-560).

This example is the same with the butane and cannabis. Butane is a stronger solvent and if left too long will continue to pull out more and more polar compounds like chlorophyll. With the fine-tuning of CO2, you can eliminate or you can pull out the chlorophyll if you choose the wrong conditions.

So fast extractions are possible with butane but little control of all the material, while CO2 can be tunable and therefore is able to collect all of the same material, just through a segmented process.