As the cannabis industry evolves, more and more cannabis laboratory certification programs are popping up. However, work by myself and others clearly shows the ongoing inter-laboratory variation problem in this industry still exists, which means laboratory certification is a necessary, but not sufficient, condition to guarantee your samples are analyzed properly. Here, I offer suggestions to help improve the situation.

Laboratory accreditation is the process by which an ideally unbiased, independent 3rd party is used to certify the operations of laboratories, including cannabis analysis laboratories. Examples of entities providing this service include private companies (1), nonprofits (2,3), and of course state governments (4). The list in the references is not exhaustive, and one should perform an internet search or use other means if desiring to obtain laboratory accreditation.

The goal of most laboratory accreditation bodies is to get your laboratory to conform to what is called ISO 17025 standards (5). ISO stands for the International Organization for Standardization (6), who develop and publish international standards across a wide range of industries. The purpose of the ISO 17025 standard is for “General Requirements for the Competence of Calibration and Testing Labs” (5). The process of achieving ISO 17025 accreditation is a lengthy one and involves writing down standard operation procedures, establishing quality control procedures, validating and calibrating methods, and insuring management and technicians are properly trained amongst other things.

What is the role of the United States Federal government in accrediting cannabis analysis laboratories? The Food and Drug Administration (FDA) has issued some guidance on cannabidiol (CBD)-containing materials and has approved some CBD preparations for use as medicines (7). However, since materials with greater than 0.3 weight % total tetrahydrocannabinol (THC) are still illegal at the federal level, the FDA cannot legally regulate the production and testing of marijuana and its derivatives. The 2018 Farm Bill (8) and Final Rule (9) tasked the United States Department of Agriculture (USDA) with developing a testing program to determine if cannabis plant material is legal hemp, that is 0.3% total THC or below, or illegal marijuana. The USDA in turn has asked each state to submit proposals as to how testing laboratories in that state will be operated and regulated. From my own discussions with USDA management and scientists, they have made it crystal clear that they do not accredit any specific laboratories or analysis methods, again all they do is approve state programs. Federal law does require hemp analysis laboratories to be registered with the United States Drug Enforcement Agency (DEA) (10). However, this does not mean DEA evaluates and accredits laboratories. All DEA registration means is that a laboratory has filed the paperwork and has proven that they store, use, and account for controlled substances properly. The United States National Institute of Standards and Technology (NIST) (11) is another government agency involved in promulgating standard reference materials and methods that aid in laboratory calibration and validation work. NIST is in the process of working on standard reference materials for cannabis analysis (12). However, again since marijuana is illegal at the Federal level this means they are emphasizing hemp standards over marijuana. At the end of the day then, there is no United States Federal government agency actively involved in accrediting cannabis analysis laboratories.

Are Specific Cannabis Analyzers or Methods Accredited?

As some of you know my day job is as CEO and Chief Technical Officer of Big Sur Scientific, who manufacture and sell a mid-infrared spectroscopy-based analyzer (13). A question I am frequently asked by potential customers is if the FDA, DEA, or USDA have “certified” the analyzer. To the best of my knowledge, no government agency certifies specific makes and models of analyzers. In the pharmaceutical industry, the FDA will review methods for analysis of specific analytes in specific matrices, for example, the measurement of the amount of acetylsalicylic acid (the active pharmaceutical ingredient or API) in an aspirin tablet by high pressure liquid chromatography (HPLC). The FDA has in its employ technical experts who will read through methods and carefully go over calibration and validation data. If a method is found lacking, the FDA has the power to force companies to improve their analytical methods until they pass muster, can prevent a medicine from being approved, and can even shut down manufacturing if they believe a poor analytical method is putting the public at risk. If the FDA accepts a method, this is not a blanket acceptance of a specific analyzer or analyzer technology, it only means this method is fit for purpose, that is, for the analysis of a specific analyte in a specific matrix. Thus, the acceptance by the FDA for an HPLC assay for the amount of acetylsalicylic acid in aspirin does not mean they have certified HPLC generally or the make and model of a chromatography system being used.

I have had in person discussions with USDA technical staff about hemp analysis methods. They have made it crystal clear that the USDA does not analyze hemp and they do not certify hemp analyzers or hemp analysis methods. Again, they leave it up to state governments to generate testing plans that they will then approve. The USDA’s final rule on hemp testing (10) does contain the words “gas chromatography” and “liquid chromatography,” however these are only mentioned as examples of methods that are in use. By no means does Federal law require that you use chromatography to analyze hemp.

The FDA cannot legally regulate the marijuana side of the cannabis industry and seems to be taking a wait and see attitude (to a point) on regulating hemp and CBD. The USDA and DEA are not in the business of certifying cannabis analyzers or methods. Thus, like laboratory accreditation, there is no federal government agency overseeing the overall quality of cannabis testing.

At the moment, it is state governments that bear the brunt of regulating cannabis laboratories and analytical methods. I can’t possibly review all of them here because there are 50 different states with 50 different sets of regulations. My reading of them is that in general most states require cannabis laboratories to obtain ISO 17205 certification, and the state may request that other requirements be met as well. The problem here of course is lack of uniformity. The same cannabis bud may be determined legal in one state but not another and this, of course, is not fair. There needs to be comprehensive regulation of the cannabis industry at the federal level, but that is grist for another column.

What Can Laboratory Accreditation Do for the Cannabis Industry?

In a perfect world laboratory accreditation means that there will be a written procedure for everything a laboratory does. This means there need to be standard operating procedures (SOPs) for everything from choosing and vetting analyzers, sample preparation, calibrating and validating instruments, training technicians, and management best practices. There are even SOPs for amending SOPs. As part of the laboratory accreditation process laboratories are required to produce all these SOPs, show where they are stored and how they are accessed, and show that these procedures make sense and are in use.

Ideally, all this paperwork ensures that qualified analysts use calibrated and validated analyzers to perform analyses in a standard, reproducible way yielding accurate and precise measurements. Now, accrediting bodies also do not bless specific analyzers or analysis technologies. Like the FDA, if a specific method passes their muster, it is acceptable to for use by that laboratory in that specific analysis. This says nothing about whether the same analyzer or technology will work well at any other laboratory, or in any other application.

Ideally, if laboratories are accredited, such as with ISO 17205 certification, they should get the same results on the same samples. In other industries we insure this by having standard reference materials of known composition analyzed by many laboratories in a round robin fashion. Laboratories that meet some acceptable level of accuracy and precision on these samples are good to go. Those laboratories that do not pass these tests can lose accreditation unless they improve.

In non-cannabis industries standard reference materials are frequently provided by NIST (11). However, again NIST reference standards for our industry do not yet exist, and ones for marijuana or its extracts and distillates may never exist unless current federal law changes. This means it is difficult to compare results across cannabis laboratories because we do not have a full suite of standard reference materials for doing so.

The Reality: Inter-Laboratory Variation Is Still with Us

Others and I have researched and written extensively on the inter-laboratory variation problem in cannabis analysis (14–19). Briefly, the problem is that different laboratories consistently get different results on the same samples. As an example, I draw your attention to one of my own papers, which I believe was the first peer-reviewed paper published in 

 (14). In that work, we took a batch of marijuana distillate, known to be pesticide free from multiple analyses, and spiked it with known amounts of six different pesticides. We then submitted these samples in duplicate to five ISO 17205 certified, state licensed laboratories in California. The false negative rate, that is the percentage of the time pesticide was present, but the laboratories said it wasn’t, was 78% (14). The results are seen in Table I (14).

These results are appalling, and mean the public is being poisoned by cannabis products containing illegal amounts of pesticides.

In the same study we submitted the same batch of marijuana extract in duplicate to the five laboratories for cannabinoid profiles. The THC values for these samples obtained varied widely as seen in Table II (14).

The measured concentrations of THC varied from 77.83% to 94.46%, a range of over 16 wt.%. The distillate was a simple sample, contained a high amount of analyte, thus the wide spread in values should not have been observed. What the five laboratories had in common is that they all measured the THC values by HPLC.

Mid-infrared (IR) analysis of the same samples gave a much narrower spread of values as seen in Table III (14).

Note that the data range here is 4.52 wt.% THC, indicating that the distillate sample was homogeneous. This means the wide spread of THC values as measured by HPLC seen in Table II was not due to the sample, but real variations amongst the laboratories. We also concluded that since the spread in the HPLC data is 3.7 times greater than for mid-IR, that mid-IR is more precise for distillate analysis than HPLC (14).

Remember, all of these laboratories were licensed and accredited. Why did we get such variable results? Shouldn’t ISO 17205 and other accreditations protect us from results like this. In theory yes, but in reality, they don’t for several reasons:

For true laboratory-to-laboratory standardization we need not only pure solutions of cannabinoids or pesticides in solvent, we need what NIST calls matrix reference materials (MRMs). These are actual cannabis biomass, extract, and distillate materials with known amounts of analytes in them. The importance of matrix reference materials is that it allows us to test how sample extraction affects results. Analyzing a solution of pure molecules skips the actual sample extraction process and thus tells us nothing about it. As I have pointed out before, we do not yet have a good set of MRMs for cannabis laboratories to use, and hence no way to compare results from different laboratories to promote standardization (15,16). This is why I recommend never comparing results from different cannabis analysis laboratories.

Just because a laboratory has an SOP does not mean it will be used. Just because a laboratory has an SOP does not mean that for a given analysis the analyst will follow the SOP correctly. People make mistakes, and in the absence of constant supervision it is impossible to eliminate them.

I have been involved in several laboratory certification and audit processes. My observation is that the people sent to perform the certification or audit process, though they are definitely smart and mean well, are generally not experienced analytical chemists. These people can ensure that all required SOPs exist on paper, that they are in a correct format and readily available. That is, these people can make sure a laboratory has SOPs, but they are not capable of ascertaining whether those SOPs are scientifically sound. For example, ISO 17205 certification does not guarantee that a laboratory extracts cannabis biomass correctly, or that all laboratories do it the same way, it just certifies that a specific laboratory has a written extraction procedure in place. Until people with better qualifications are hired for laboratory accreditation, inter-laboratory variation will continue to be a problem.

At the end of the day then, laboratory accreditation is necessary but given the current state of the industry it is not sufficient to guarantee all customers will get precise and accurate results.

We need more and better matrix reference materials and laboratory accreditors. Until that happens, what should we do? Let’s restrict our discussion to cannabinoid analysis by HPLC. In each state, for example, in California, the state government should vet HPLC methods until they have a method they trust, which we will call the “golden method.” They then should insist that all chromatographs in that state use this golden method, and make each laboratory prove that its chromatographs get the same results as the golden method. This will tide us over until the bigger problems outlined above are solved.

Cannabis laboratory accreditation programs exist and require cannabis laboratories to have written SOPs. The federal government has done little to accredit laboratories, and state governments vary as to how they do things. Ideally, laboratory accreditation means customers will obtain precise and accurate data, and that different laboratories will get the same results on the same samples. The reality is that inter-laboratory variation is still with us and has several causes including a lack of matrix reference materials and the use of accreditors who are not experienced analytical chemists. Until these problems are solved, adoption by states and accrediting bodies of a “golden” method may suffice.

ISO 17025 Accreditation Process (pjlabs.com).

Cannabis Laboratory Testing Accreditation Program | A2LA.

ANAB Laboratory Accreditation (ansi.org).

Testing laboratories - Department of Cannabis Control.

ISO - ISO/IEC 17025:2017 - General requirements for the competence of testing and calibration laboratories.

ISO - International Organization for Standardization.

FDA and Cannabis: Research and Drug Approval Process | FDA.

115th United States Congress, Senate Bill S.2667,” Hemp Farming Act of 2018.

Federal Register: Establishment of a Domestic Hemp Production Program.

Hemp Analytical Testing Laboratories | Agricultural Marketing Service (usda.gov).

National Institute of Standards and Technology | NIST.

NIST Tools for Cannabis Laboratory Quality Assurance | NIST.

M.O. Bonn-Miller, M.J. E. Loflin, B.F. Thomas, J.P. Marcu, Travis Hyke, and R. Vandrey, 

https://www.seattletimes.com/seattle-news/marijuana/some-pot-labs-in-state-failed-no-pot-at-all-says-scientist

https://www.nbcbayarea.com/investigations/Industry-Insiders-Warn-of-Fraud-at-Marijuana-Testing-Labs-458125743.html?_osource=SocialFlowFB_BAYBrand

, 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 

The inter-laboratory variation problem still exists, which means laboratory certification is necessary, but not sufficient to guarantee your samples are analyzed properly. Here, Smith offers suggestions to help improve the situation.

Laboratory Accreditation: Is It Enough to Guarantee Your Samples Are Analyzed Correctly?

Decades ago, a relentless campaign of stigma and misinformation was unleashed upon cannabis. By coming together and sharing our personal journeys as well as medical and scientific findings we have begun to reposition cannabis as a medicinal, natural product. However, there still remains a very deep and pervasive stigma surrounding many other psychotropic natural products such as psilocybin mushrooms, ahayhuasca, mescaline, and peyote. There has been such an amazing increase in interest in psychedelic medicine that the Cannabis Science Conference is adding a Psychedelic Science Track for CSC West in Long Beach, CA (February 2–4, 2022). Join us and a group of key opinion leaders in psychedelic medicine to learn more about this emerging market.

For this installment of “Cannabis Crossroads”, I sat down with David Heldreth, Founder and CEO of Panacea Plant Sciences. Heldreth is a scientist, innovator, educator, and explorer helping to move psychedelic medicine and science forward. We discuss everything from the rise in interest in psychedelic medicine and his company, Panacea Plant Sciences, to the interesting parallels between cannabis and psychedelics. Heldreth also shared advice for those interested in getting into this emerging industry.

We have seen a rise in interest in psychedelics over recent years. Why has psychedelic medicine become a hot topic recently?

I think there has been an ever-increasing openness to speak about the current public health crisis surrounding mental health and addiction in our society. This is due to a combination of factors, but it faces all facets and pieces of society—from PTSD in veterans from war to LBGTQ+ victims of hate crimes or a worker at a lumber mill who had a back surgery and is addicted to the opiates the doctors over prescribed. These problems are difficult to treat and often resist the current treatment regiments. This has led people to seek new answers such as psychedelics. At the same time there has been a renaissance in scientific research on these very subjects. I believe the COVID outbreak has galvanized both of these topics at the same time with a large push to research something new in medicine and to treat the mental health consequences of quarantines. Society is hungry for new answers.

How did you get involved in psychedelic medicine?

My history with medicinal psychedelics mirrors my history with medical cannabis. I have had many surgeries and nerve pain issues from past injuries. Additionally, I have faced my own anxiety, depression, and PTSD issues due to things from my childhood. Cannabis, mescaline, psilocybin-containing mushrooms, LSD, DMT, ketamine, and MDMA at different times in different ways provided what I needed in addition to therapy and group, family, and friend support. As such I was able to quit utilizing all the medications I was prescribed as a child and young adult from opiates, muscle relaxers, and related items for the pain-related issues along with quitting all benzodiazepines and other medications for the PTSD, anxiety, and other conditions.

These profound experiences and treatments led me to want to understand how these items worked. With a background in marine biology and aeronautical engineering, I began applying myself to learning what research did exist and then cultivating and exploring these medicines directly. Over time this led me to form companies, develop technologies, and create methods to treat mental health and other medical conditions and also improve methods to create these medicines.

How is Panacea Plant Sciences helping advance psychedelic science? Which psychedelics are you interested in? Are there any special projects that you are involved in that you wish to highlight?

Panacea Plant Sciences' (PPS) goal is to be the intel inside for psychedelics and natural medicines. PPS has developed a variety of technology and IP around the cultivation, extraction, isolation, packaging, shelf-life, and medical formulation uses of cannabis and psychedelic plants, fungi, lifeforms, and compounds. We are currently working with universities to develop unique non-heated delivery methods among other projects.

Panacea Plant Sciences is not focused on a single compound, plant, fungi, or treatment, but rather at being ahead of the pack in all of the fields and compounds with a goal to prepare the research, patents, and IP that other groups will then take to a final commercial use. We have projects relating to mescaline, DMT, psilocybin, MDMA, ketamine, LSD, and Shulgin compounds among others in motion.

I am most proud of our work with indigenous reciprocity. We have stated that we will work within the principles of the Nagoya Protocol, which is an international treaty to protect biodiversity and indigenous rights. Canada and the US are some of the only non-signatory nations. This is due to a desire to allow US companies to steal and pirate lifeforms from other countries.

Beyond this PPS has designated in perpetuity that 32% of our equity will be preferred shares that can only be held by indigenous groups and 401c3's which are associated with them or related environmental groups. These preferred shares have voting rights and 10x divided rate so that they can hold them and draw funds from dividends for any projects they see fit in their communities. The money will also help fund environmental work to protect the species involved.

For mescaline projects we are currently working and speaking with Sia. Sia is the Mother Church of the Comanche Native American Church 1918 Charter Association (NAC). NAC and related groups are allowed to possess and utilize 

 under federal law. Sia was founded by Wahathuweeka William Voelker and Kwihnia makwetsoi okweetunia: aka Troy. Sia: The Comanche Nation Ethno-Ornithological Initiative is a traditional NAC organization whose mission is the preservation of the Eagle and Peyote through cultural understanding in history, science, and spirit. Sia is a cultural breeding center with many world firsts in natural and artificial breeding. All molted feathers go to the only feather tribal repository in the US to promote indigenous spiritual sovereignty for 574 tribal nations. Sia is the official repository and archive for the history, culture, and spirit of the Comanche and Numunuh people.

We are also lucky enough that we have Dr. Martin Terry as an advisor. He is currently licensed by the DEA for work with 

. Dr. Terry has been a leading researcher for 

Psychedelic science faces stigma similar to cannabis. Do you see this changing over the next decade? What will need to happen to make psychedelic science more accepted and respected?

Similar to my own path, I believe that cannabis and psychedelics have many parallels. I think that working on getting decriminalization bills, as well as legalization bills passed across the country in states and cities is going to be key. At the same time research, and even more directly research with human patients, I believe will be a big part in changing the narrative. As people see others become healed by these medicines it changes their view of them. Just recently Texas passed a bill or law that will begin research for psychedelics and PTSD. This is the kind of thing I think will spread across the country and lead to the changes we want.

Do you have any advice for others looking to get into the psychedelic science space?

Be patient and don’t expect anything to happen quickly. Research and read as much as you can about the industry and the science. I recommend Google Scholar (scholar.google.com) and Sci-Hub as resources for anyone wanting to learn about the science in the cannabis or psychedelic spaces. Pick a path as well. What do you want to do in psychedelics? Are you a grower, extractor, formulator, doctor, facilitator, marketer, web designer? There will be needs for many types of people and roles. Once you figure those pieces out, be persistent and then lobby and advocate at your local, state, and federal government. That is how we protect psychedelic medicines and how you connect with others who are like minded.

We just announced a Psychedelic Science Track at our 2022 Cannabis Science Conference West in Long Beach, CA, and we hope you will join us and share your data!

I hope that we have some early data from some of our projects to present with you in 2022. The DEA and governments are slow, so parts of this are out of our hands. However, currently things are moving at light speed for this industry!

Psychedelic medicine is a quickly emerging industry and I’m excited to see more advancement in this field. I’d like to thank David for sharing a closer (and personal) look at the rise of psychedelic medicine and science. I believe this is a topic that we’ll be seeing a lot more information and data on soon.

David Heldreth is a patented inventor as well as the founder and CEO of both Panacea Plant Sciences, a biotechnology company developing a portfolio of cultivation and related IP and patents around the cannabis plant, psychedelic life forms and formulations; and Ziese Farms, a hemp food company which has led the way with FDA allowances for hemp microgreens. He is also a former Chief Science Officer of a natural products company focused on terpene formulation. He testified at the historic FDA hearing on cannabis, CBD, CBG, CBC, and terpenes in our food supply on May 31, 2019. He is a leading scientist, inventor and educator in the cannabis and psychedelic communities.

 is the columnist and editor of “Cannabis Crossroads”
and a contributing editor to 

 magazine.
Crossney is also the president and CEO of Cannabis Science Conference.
Direct correspondence to: 

Cannabis Crossroads

David Heldreth, Founder and CEO of Panacea Plant Sciences, discusses the rise in interest in psychedelic medicine and more.

A Closer Look at the Rise of Psychedelic Medicine and Panacea Plant Sciences

Cannabis and cannabis-related samples were collected from state regulated dispensaries

in Northern California over a seven-year period and tested for bacterial and fungal contaminations using culture-based technologies. Data indicates that most bacterial contaminations of flowers occur post-harvest caused by poor hygiene and handling protocols, whereas solvent created oils and waxes are mostly bacteria free. High bacterial numbers occur in water-based concentrates and kief (plant trichomes). Yeast and mold numbers were common on dried flowers as these organisms occur naturally on cannabis. This study offers guidance to establishing meaningful quality standards for the commercialization of cannabis and cannabis-related products.

 continues to gain popularity and acceptance in America, it becomes necessary to understand microbiological behavior for the proper development of Hazard Analysis Critical Control Point (HACCP) and quality assurance protocols. The concept of quality assurance in this industry has yet to be widely accepted, partially due to the absence of relevant scientific research. Currently, microbiological standards are based on comparison and anecdotal information often from non-scientific sources (1–7). Yet, many states have selected specific limits of a small number of microbiological species (1,2), often declaring strict guidelines. As a result, the microbiological safety of cannabis remains obscure along with hazard and risk criteria needed for quality assurance development (8).

The current study records broad spectrum, presumptive microbiological information and provides long term data on microbial loads commonly occurring on California cannabis and cannabis products. These long-term data offer preliminary insights and guidance for the establishment of more meaningful scientific studies and quality assurance protocols for safe commercialization of legal cannabis.

Samples of cannabis and cannabis-infused products were collected from Northern California growers, distributors, and dispensaries between 2012-2019. Flower and shake samples were collected in sterile whirl-pak bags or in retail package containers.

Bacterial and fungal fail rates were selected and modified based upon widely accepted food standards for milk and dairy products detailed in AOAC 986.33 Aerobic Plate Count (APC), AOAC 991.14 Coliform/

 and AOAC 997.02 Yeast and Mold. Next, 1000 mg of each sample was placed into 9 mL of sterile Butterfield’s Phosphate Buffer (3M). Following 10 min, a 1 mL inoculate was pipetted onto an APC Petrifilm, an 

/coliform petrifilm, and a yeast and mold petrifilm (3M) and spread over the plate using a plate spreader. Aerobic plate count and 

/coliform petrifilms were incubated at 35 ± 2 °C for 48 ± 6 h, removed from the incubator, and enumerated according to manufacturer's instructions. The yeast and mold petrifilms were incubated at 20–25 °C for 72 ± 6 h. Colonies were enumerated deviating from the manufacturer’s instructions by dividing the colony number by a factor of 20. This division is necessary to accommodate for the removal of the additional buffer step suggested by the manufacturer. Yeast and mold colonies were differentiated based on morphological features: those exhibiting grey, blue, or green color with small, circular shapes displaying no filamentous features were counted as yeast. Colonies exhibiting black, grey, green, yellow, red, or other coloration and large, filamentous morphology were counted as mold. ATCC 9027 

 Newport were used as bacterial positive controls. ATCC 10231 

 were used as yeast and fungal positive controls. Blank controls were plated daily.

A total of 59,088 samples over a broad spectrum of sample types submitted to CW Analytical for microbiological quality assurance testing were included in this study. Of these sample types, 28,483 dried flowers, 354 loose dry leaves (shake), 253 pre-rolled cannabis cigarettes, 1991 hashes, 533 kiefs, 10,313 solvent-processed concentrates, and 17,925 infused edible products such as infused oils, tinctures, liquids and beverages, infused fats and butters, and other edible products were tested.

The bacterial fail rate (samples exhibiting >100,000 CFU/g) of dried flowers was measured at 14.48% of the total sample of flowers (Table I). Generally, cannabis flowers exhibit low bacterial loads during cultivation (observational data) (see note below). In most cases, flowers exhibiting high bacterial loads have been subjected to contamination post-harvest (observational data) (see note below). [Note: This has been observed from survey and conversation with cultivators via discussion of their test results. Additionally, this has been observed on cultivation facility walkthroughs and execution of remediation and good manufacturing practices.] It is postulated that the multiple terpenes, endophytic organisms, and possibly the cannabinoids themselves produced by cannabis may act as an antibacterial compound, keeping bacterial loads lower during the plant life cycle (9–14). This is supported in this study by unpublished data showing low bacterial loads on growing plants and >500,000 CFU/g found on plant material suspected to be poorly handled post-harvest. Subsequent testing to sample failures indicated 

 detection on only 3.16% of dried flower, 6.71% detection of coliforms, and 5.14% detection of 

, further supporting secondary contamination origins (Table II–IV). We postulate that contaminations originate post-harvest from unclean rooms, poorly cleaned tools, or poor personal hygiene of operators.

The yeast and mold fail rate (samples exhibiting >10,000 CFU/g) for flowers was measured at 15.83% (Table V). Fungal species are known to routinely inhabit cannabis species (15–17). Late season fungal growth can cause a great deal of spoilage to a cultivation and decrease crop yields (18). However, the presence of fungal spores does not indicate that a specific fungal species is actively growing on the sample in question. The higher detection rate measured in culture may indicate a higher probability of positive growth; further study is needed to confirm this hypothesis.

Mechanically processed concentrates such as bubble hash or kief exhibit higher microbial loads. The bacterial fail rate of hash was measured at 58.51% of the total hash sample. Hash is typically produced by cold water filtration of leaves and flowers through a series of smaller filters and therefore should be considered a product of the Earth, with expected high bacterial loads. The detection of presumptive 

(1.81%) support the correlation between cleanliness, hygiene and lower microbial numbers (Tables II–IV). We suggest that the low yeast and mold loads (≥10.000 CFU/g) at 2.78% exhibited are caused by repeated water flushing, which may reduce the number of fungal spores per batch by dilution, or mechanical trapping in the filters (Table V).

Similarly, the bacterial fail rate of kief was measured at 43.71% of the total kief sample collected (Table I). Kief consists of concentrated plant trichomes that are removed from the surface of flowers and leaves through physical processes. Like hash, kief exhibits detection rates for 

 (2.56%) that are higher than cannabis products processed by solvents, high temperatures, or pressure. Yeast and mold fail rates in kief at 8.18% were higher than hash (2.78%) possibly from the mechanical trapping of fungal spores from the environment by this adhesive-like plant material during processing (Table V).

Solvent, Temperature, and Pressure-Based Concentration

The bacteria fail rate of resin, crystals, waxes, e-cartridges, and sauces, processed by solvent, temperature, or high pressure-based processes was measured at just 0.22% of the total sample, and the yeast and mold fail rate (samples exhibiting >10,000 CFU/g) was measured at 0.00% (Tables I and V). Solvents (butane, ethyl alcohol, propane, hexane) are typically used in the production of these concentrates, and may be combined with pressure and temperature extremes (heat, LN₂, CO₂). It is thought that these treatments effectively inhibit all microbiological species, and that increased handling or processing post-manufacturing leads to higher chance of contamination.

The bacterial fail rate of infused-edibles was measured at 2.89% of the total infused-edible sample (Table I). Detection of 

 in edibles were calculated at only 0.13%, coliforms at 0.47%, and 

 at 1.89% (Tables II–IV), while yeast and molds in loads exceeding 10,000 CFU/g were detected at just 0.39% (Table V). This data represents a number of edible forms including chocolate, cookies, brownies, gummies, capsules, tablets, mints, and a myriad of other food matrices. The low failure rates in this category may indicate that most producers understand the importance of hygiene and cleanliness during the manufacturing and produce temperatures that either clean or pasteurize the products.

Tables I and V illustrate the typical microbial load on cannabis cultivated and manufactured in Northern California. The current data, compared to the rare and anecdotal reports of microbial infections linked to cannabis (19–22), suggests that the vast majority of cannabis and cannabis products are microbiologically safe for human consumption. This study illustrates possible quality assurance thresholds and limits, based on what is typically encountered, and what level of microbial load is atypical to the majority of what is being sold on the market (23–26). This study is limited by the utilization of plating as a primary testing practice, indicating only presumptive organism identification. Correlations with technologies such as MALDI-TOF MS, PCR, selective growth agars, and biochemical characterization need to be included in the future for proper validation. Continued areas of research include: the identity and frequency of particular organisms (bacterial and fungal), sources of microbial contamination and pathways to mitigation of contamination, and the beginnings of understanding plant-microbe interactions specifically related to cannabis cultivation. Investigation into how these cultivation parameters relate to the occurrence of organisms will be crucial for setting future quality assurance measures, managing pesticide and chemical residue applications, and refining sustainable cannabis cultivation practices.

”Marijuana Labeling, Concentration Limits, and Testing” Oregon Secretary of State Archives Division. Web (2017).

“Department of Revenue Marijuana Enforcement Division, Medical Marijuana Rules. 1 CCR 212-1,” Code of Colorado Regulations. Web.

“Department of Revenue Retail Marijuana Code 1 CCR 212-2,” Code of Colorado Regulations. Web.

“WAC 314-55-102: Quality assurance testing,” Washington State Legislature. Web (2013).

“NAC453A.658. Sample testing; disposal of samples; standards; laboratory test results; grounds for disciplinary action,” Nevada Administrative Code. Web.

Olson Hagel & Fishburn LLP, “Initiative documents for the Control, Regulate and Tax Adult Use of Marijuana Act (amended) (PDF), 15-0103” – via California Office of the Attorney General (2015).

“Cannabis Microbial Testing Regulations By State,” Medicinal Genomics (2020). Web.

C. Hellerman, “Scientists Say the Government’s Only Pot Farm Has Moldy Samples - and No Federal Testing Standards.” PBS, Public Broadcasting Service, www.pbs.org/newshour/nation/scientists-say-governments-pot-farm-moldy-samples-no-guidelines (2017).

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 are with CW Analytical Laboratories, Inc., in Oakland, California.



R. W. Martin, K. Wheeler, C. M. Macdula, J. Jacobo, and E. R. Savage, 

Peer-Reviewed Article

This study offers guidance to establishing meaningful quality standards for the commercialization of cannabis and cannabis-related products.

Microbiological Implications  of Commercial Cannabis in Northern California:  A Survey of Bacterial  and Fungal Contamination

Developing a tablet dosage form for the cannabis or hemp industry offers many advantages for consumer compliance and manufacturers alike. The consumer can now administer a known concentrated amount of tetrahydrocannabinol (THC) or cannabidiol (CBD) in different tablet forms including a lozenge with flavors like a mint candy, orally disintegrating tablets (ODT, orally disintegrating in less than 30 seconds), a bilayer tablet with one layer as immediate release and the other with extended release, an effervescent form to disintegrate in water as a flavored beverage, and many more delivery options. A tablet form also offers elegant shapes and sizes for product branding, ailment identification, concentration amount, and more. Manufacturers benefit from the high output rates from tablet presses up to millions per hour, if developed properly. The process of developing a THC or CBD tablet form is the same as developing a pharmaceutical tablet with an active pharmaceutical ingredient (API). The API (THC or CBD concentration) must be uniform within tolerance for every single tablet manufactured. This development process is both a science and art form. The tablet development process requires the appropriate selection of excipients. The API (THC or CBD) amount is only a fraction of the formula and the excipients are inactive functional ingredients that provide the bulking agent, binding agent, dissolution, flow agents, powdered lubricants, flavors, colors, and more. Furthermore, THC and CBD are typically in a distillate form and require loading to a carrier material. All of these materials must be mixed into a homogeneous manner with acceptable particle size distribution and high compactibility on the tablet press. A series of experiments are carried out in the laboratory including powder micromeritics, compaction profile studies to understand the mechanical robustness, and its failure points. These fundamental studies are critical processes to ensure successful manufacturing of THC and CBD tablet dosage forms.

Tablets comprise the largest group of delivery systems for the pharmaceutical and dietary supplement industries. This technology offers an opportunity to the cannabis industry to allow orally administering a consistent and defined amount of cannabidiol (CBD) or tetrahydrocannabinol (THC). Common types of tablets include immediate release, modified release, orally disintegrating, effervescent, chewable, lozenges, and bilayer. Advantages include ease of accurate dosing if developed properly, physical and chemical stability, elegant appearance for distinctive identification, competitive production costs, and a high level of patient acceptance and compliance. Tablets are a complex drug delivery system, and their design, development, and manufacture should not be underestimated or significant problems will arise at some stage of the process. There is no doubt that many tableting problems occur because of the failure to fully understand the properties of the raw materials and how they behave on the tablet press.

There are three main processes used in the tablet manufacturing industry for developing high quality tablet forms: Direct compression (DC), dry granulation or roller compaction (RC), and wet granulation (WG) which can be high shear, low shear, and fluid bed technologies. RC and WG processes are typically used to improve the powdered formula’s flowability by increasing its particle size and density. Flowability is a critical attribute for tableting and high-speed tablet presses require acceptable flow properties to uniformly fill the die cavity. If the proper excipients are chosen and the blending process is properly followed, then granulation can be omitted from the process. This is true if the cannabinoid is already in powder form (that is, isolate), but if the cannabinoid is in oil or crude form then loading the oil on a carrier is needed; a common way to load the oil is through a low shear process. The carrier material must be able to hold a significant amount of oil and many carriers are available including maltodextrin, silica, and phosphates. Saturating the carrier with oil can impact the flowability and compactability, so a series of laboratory tests can ensure the proper amount for successful tableting.

In the comparative study described here, three common oil loading material classes were used with CBD distillate containing 89.03% w/w CBD concentration. A 10% drug load at 89.03% CBD potency was 11.23% w/w distillate loading and 88.77% w/w carrier material were mixed using a low shear mixing process. The carrier materials included maltodextrin, tri-calcium phosphate, and silica (see 

). The final tablet formulation will then include Mannitol (see 

), which is the bulking agent, and a vegetable-based magnesium stearate was used for the lubricant. The carrier material or intermediate blend (IB) and the Mannitol were then screened with a #30mesh sieve and blended in a tumble mixer for 3 min. Finally, the magnesium stearate was screened using a #40mesh sieve and blended with the formula in a tumble mixer for an additional 2 min. Screening the raw materials is a critical process to break up any agglomerates and ensure a more homogeneous blend. This will ultimately improve powder flow into the die cavity and help provide consistent tablet weights and content uniformity. Also, the magnesium stearate is the powdered lubricant that will reduce the force required to eject the tablet after compression. Overbending or an excessive amount of lubricant is a common issue that can lead to reduced powder flow properties, lower tablet strengths, tablet capping (which is a fracture along the horizontal plane of the tablet), and surprisingly, punch face sticking. Adding more lubricant to the formulation may initially help reduce sticking but an excessive amount, sometimes higher than 1.0% w/w or over blending will weaken the particle-to-particle bonding under compaction which can cause the particles to adhere to the punch faces instead.

Before compacting these formulas on the tablet press it is prudent to evaluate the micromeritics. 

 is the science and technology of small particles. In the tableting arena, we focus on particle size and size distribution, particle shape, volume and surface area, density, flow properties, and porosity. At the very least particle size, distribution, density, and flow should be evaluated before tableting.

Particle size distribution can be measured by several methods including sieving, microscopy, sedimentation techniques, optical and electrical sizing zone method, and laser light scattering techniques. We will focus on a simple method called sieving where we used an atomic sonic sieve sifter at 10 min of run time. Six sieves were stacked on top of each other where each lower sieve has a smaller aperture size than that of the sieve above it. Sieves can be referred to as their aperture size in micrometers (µm) or by their mesh size which is the number of wires per linear inch. The test we used for this experiment utilizes 850, 600, 250, 150, 125, and 75 µm sieves. The sample material is poured onto the 850 µm screen, and the sieve sifter provides cycles of vibration and pulsing to separate the particles. Any material that passes through a 75 µm screen is considered fine materials. 

 depicts the percentage of materials that were separated by the screen sizes.

The maltodextrin blend provided the best particle distribution results with more than 66% of the blend held on the 250 µm sieve and less than 9% under the 75 µm sieve. We look for a unimodal curve and less than 15% fine materials. A bimodal curve will show two peaks, a peak with large particle sizes and a peak with small particles. This causes an issue with possible segregation, high tablet weight variations, and potential content uniformity issues. An extreme example of this is like trying to blend marbles and sand and when the tablet press starts up the vibration caused from the machine will separate the marbles from the sand and the resulting die fill from the tablet press will not be uniform
(see 

The silica and tri-calcium phosphate blends did provide a unimodal distribution curve, but an excessive number of fines were found for both blends. The excessive number of fines could cause powder flow issues and could lead to tablet robustness issues and potential sticking to the tablet press tooling punch faces. As mentioned above, less than 15% fines is desirable for tableting. A small number of fines will allow filling of the air voids between particles, but an excessive amount causes inter-particulate bonding issues during the compaction event which is needed to produce robust tablets for shipping and handling during manufacturing and to the consumer.

Compressibility and Flow Characterization

Measuring the formula’s bulk and tapped density is another test to evaluate the micromeritics. The 

 is the apparent powder density under defined conditions and the 

 is the apparent density obtained under stated conditions of tapping. The bulk density is valuable because this will allow the formulator to understand if the required mass of the final tablet will fit into the dosing depth fill that is available on the tablet press (see 

). The tapped density as compared to the bulk density will allow the evaluation of the compressibility or the ability to reduce in volume, which classifies the flowability characteristics.

The bulk density of a powder is the ratio of the mass of an untapped powder sample and its volume including the contribution of the interparticulate void volume. Hence, the bulk density depends on both the density of the powder particles and the spatial arrangement of particles in the powder bed (see 

The inter-particulate interactions influencing the bulking properties of a powder are also the interactions that interfere with the powder flow. A comparison of the bulk and tapped densities can give a measure of the relative importance of these interactions in a given powder. The compressibility index and Hausner ratio are common ways to evaluate flow characteristics (see 

 depicts the three carrier formulations with their bulk and tapped densities, Hausner ratio, and compressibility index. The maltodextrin blend resulted as “passable” flow, the tri-calcium phosphate blend also resulted as “passable,” and the silica blend resulted as “poor” flow. Formulas that are characterized as “poor” still can produce quality tablets, but these formulas typically have more challenges during manufacturing and production rates are reduced to compensate for the poor flow characteristics.

Moisture content analysis is another important factor to consider for successful tableting. Excessive moisture can adversely impact the physical properties of the tablet, which in turn affect the chemical reactivity and binding properties that define the product’s shelf-life. In some cases, the presence of moisture effects the consistency and stability of the tablets. Too much moisture will cause agglomeration of the powder particles and will affect the flowability. Too little moisture can cause binding issues resulting in a poorly compacted tablet with very low tablet strength. Generally speaking, less than 1% moisture can be too low causing very low tablet strengths and greater than 4% is too moist causing flow issues which turns into weight consistency and content uniformity issues. Effervescent tablets are hydroscopic in nature and tend to absorb the environmental moisture from the air. Hydroscopic materials must be processed in a controlled environment with a recommended relative humidity not to exceed 40%. The moisture content for all three formulas were found to be acceptable. The maltodextrin blend resulted in 4.17%; the tri-calcium phosphate blend resulted in 1.25%; and the silica blend resulted in 3.00%.

The compaction study described below was performed on the NP-RD10a single station tablet press and AIM data acquisition system. Whether your machine is a single station or rotary tablet press the powdered materials still undergoes compressive forces in a confined space, causing a reduction in volume. At first, the low applied pressure cases particles to rearrange and pack more closely, and porosity thus decreases. As pressure increases, the dimensions of the particles change. They can either fracture into smaller discrete particles (fragmentation) or they undergo a temporary (elastic) or permanent (plastic) deformation into new shapes. At higher pressures, the particles that fracture could further rearrange and undergo additional deformation.

Materials that undergo fragmentation are typically less sensitive to weakening when powdered lubricants (that is, magnesium stearate) are added. As mentioned earlier, lubricants commonly inhibit bonding between particles, but when the particles fragment, new and clean surfaces are exposed, strengthening the bond. Particles that fragment are also less sensitive to the speed of the compression event. Materials that undergo plastic deformation are known for creating high-strength compacts at relatively low applied pressures, which stems from the greater number of inter-particulate contact points during the deformation process. That strength, however, may decrease when lubricants are added and when the rate of compression increases. Elastic deformation refers to a particle’s partial or full recovery to its original shape after compression loading ceases. Time-dependent elastic recovery is called 

, and the factors that influence compression time are press speed, turret velocity, compression roller sizes, and punch head dimensions.

To conduct a compression study, select the tablet’s target weight and keep it fixed. We selected 200 mg for each blend to compress. Next, we collected samples of tablets made at different compaction forces (low to high) and measure their weight, thickness, and breaking force (also called hardness). Other post compaction measurements include friability, disintegration, and dissolution. Once this is collected you can then plot each attribute or characteristic as a function of the applied compaction pressure. 

 depicts a tabletability profile that is the tablet tensile strength as a function of the applied compaction pressure. This is a normalized way of evaluating the tablet robustness independent of its mass and size. Smaller and lighter weight tablets can be made at early development and if the size and mass changes the tabletability profile does not change. This adds many advantages including material sparing process to save investment costs, comparing tablet robustness with tablets of different sizes and weights, and a defined process to run profiles even when you know little to nothing about the formulation.

Compaction pressure can be calculated from the applied force and the cross-sectional area of the punch face (see 

). This allows you to compare the loading of different size tablets.

Tensile strength, which can be calculated from the breaking force and tablet dimensions, allows you to compare the mechanical strength of different size tablets. The tablets for the experiments summarized here were made using 10 mm round flat face punches and the values were calculated using the Fell-Newton equation (see 

In this example, we compressed all three samples at 100, 150, 200, 250, and 300 Mega Pascals (MPa). Sample tablets were collected at each pressure for an average tablet weight, thickness, and breaking force. We chose these pressures as they are the most common applied loads for pharmaceutical, dietary supplements, and candy. Typically, 100–200 MPa is used for pharmaceutical products whereas dietary supplements and candy are typically compressed between 200–300 MPa. When drug loads are low for pharmaceutical products then the compactible excipients are a high percentage of the formula, which will require a low compaction pressure to produce a robust tablet. Dietary supplements can have more than 10 active ingredients in the formula, and they usually are not very compactable, which requires higher compaction pressures. Candy tablets can range in pressure but when it is developed as a lozenge to suck on and slowly erode in the mouth, these tablets are very hard from the high compaction pressures.

As the compaction pressure increases, we expect the tablet strength to also increase until it reaches it’s maximum compactability. A robust tablet range is 1.5–2.0 MPa tensile strength. This strength provides a robust tablet that can survive shipping and handling. If your product is an effervescent or orally disintegrating tablet, then a tensile strength of less than 1.0 MPa is appropriate and in some cases less than 0.5 MPa. This is due to the fast disintegration times required from these products.

 all three formulas increased in tablet strength with increased compaction pressure even up to 300 MPa of compaction pressure. This is encouraging as some materials will reach its maximum compactability before 300 MPa and this can cause issues at high-speed manufacturing. After a product reaches its maximum compactability it reduces in strength with increased compaction and can cause a phenomenon called 

 where the tablet fails across the horizontal plane. This is an unacceptable condition that requires reformulation work. Although there are remedies that can be done on the tablet press and compression tools including adding pre-compression force to better consolidate the particles before final compaction, slowing the turret speed down to increase the compression times, and by modifying the punch head design for longer or shorter dwell times (the time in milliseconds under maximum compaction force) and tapering the die to allow an easier path for air release.

The tri-calcium phosphate blend provided the strongest tablet reaching 1.5 MPa tensile strength at only 100 MPa of compaction pressure. This blend will require the least amount of compaction pressure and force, which reduces wear and tear on the tablet press and punches. Since the formula didn’t show a plateau on tablet strength, this product has room to increase force if needed when transferred to high-speed manufacturing. The silica blend reaches 1.5 MPa tensile strength above 200 MPa of compaction pressure and the maltodextrin blend did not reach the target strength even at 300 MPa of compaction pressure.

There are many advantages for developing a cannabis product into a tablet form. Understanding the micromeritics of the raw ingredients and final blend is crucial to ensure your product gets to market with limited issues. Powder flow, particle size, particle size distribution, and moisture content are all critical attributes to ensure consistent quality tablets with acceptable content uniformity. Normalized compaction profiling data for pressure and tensile strength will simplify the mechanical strength evaluations and paint a picture of the products robustness independent of its size. Performing these studies provides a science-based approach decision making process.

 are with Natoli Scientific in Telford, Pennsylvania. Natoli provides contract services from product discovery, design, development through scale up to manufacturing. Natoli Scientific is a division of Natoli Engineering Company, Inc.

Feature

A closer look at the fundamental studies of tablet formation that are critical processes to ensure successful manufacturing of THC and CBD tablet dosage forms.

Cannabis and Hemp  Tableting Challenges

This article proposes alternative and effective cleaning solutions for cannabis and hemp processing equipment using detergents commonly used in pharmaceutical cleaning applications to maintain the quality of safety of the drug product and integrity of the equipment. This approach would eliminate the need for cleaning with ethanol which, when used at a large scale, has numerous limitations including storage, flammability concerns, and waste handling.

The Cannabis and hemp industries are evolving at a record pace as innovations and consumer expectations have led to changes in the manufacturing environment. Extraction processes are becoming increasingly prevalent in cannabis manufacturing operations as “users prefer to consume tetrahydrocannabinol (THC) via derivatives rather than smoking dried flower. Derivative products include oils, capsules, topicals, sprays, concentrates, vapes, edibles, and infused beverages” (1). As derivative product demand increases for desirable oral dosage and edible forms, manufacturing operation capacity is often increased by adopting equipment and processes from traditional pharmaceutical manufacturing such as formulation vessels, high shear agglomeration, tablet coating, and fluid bed granulation and coating equipment in addition to the extraction equipment.

Although cannabis manufacturing has advanced, equipment cleaning processes have lagged. The focus has been on scale-up of the manufacturing process and testing as the market retail sales estimates are projected to top $25.0–30.4 billion in the United States alone by 2023 (2). Cannabis and hemp extraction present various contamination control issues and cleaning challenges resulting from plant biomass, waxes, and extracts. When cleaning processes are not optimized before scale-up, equipment cleaning may take significantly more time and resources than originally planned, possibly impacting the manufacturing schedule. Unfortunately, equipment cleaning, often considered a necessary evil, is not thought about until there is an issue.

Ineffective cleaning could also lead to lost batches and product recalls due to microbial contamination and adulteration of product from pesticides, solvents, and heavy metals. Pesticide residue not only lingers in soil and plants, but can also linger in extraction equipment (3). Biomass contaminated with bacteria, pesticides, or other contaminants could conceivably find its way into regulated infused products that use cannabis oils extracted from raw materials, which are ultimately ingested or administered topically, exposing consumers to yet another health threat (4). It is important to consider all contamination sources, whether it is introduced through raw materials or process residue when assessing the cleaning process. 

The use of ethanol (EtOH) has been the standard for cleaning cannabis extraction equipment since this may have been used in the manufacturing process, recommended by the equipment manufacturer, or was used to clean the product during small-scale development. Cleaning with ethanol may be ideal for small-scale cleaning; however, it is not suited for large-scale cleaning. Ethanol has a flashpoint of 55 °F (13 °C), which is the lowest temperature volatile organic compounds (VOCs) are emitted and will ignite. According to a document from the California EPA's Department of Toxic Substances Control and U.S. Environmental Protection Agency (5), “Most of the solvents used for cleaning are classified as VOCs which contribute to photochemical smog, and many are considered toxic as well.” Reducing ethanol by eliminating the use for cleaning lowers the risk of explosion, storage, and disposal concerns.

Because of the low flashpoint, EtOH is considered flammable; thus, large quantities of stored EtOH results in Class 1, Division 1 (C1D1) hazardous location designation. Class 1, Division 1 designation requires construction and equipment to meet National Fire Protection Association (NFPA) Publication 70, National Electric Code (NEC) environmental control measures. Requirements may include but are not limited to having greater than six room air changes per hour and explosion-proof equipment, which may add substantial costs to a new-build or expansion project.

Once large EtOH quantities are used for cleaning, the spent solution must be recycled or treated as hazardous waste. In addition to the expense associated with disposal, which was estimated at the time of this article to total approximately $2/gallon, reducing solvent waste has been one of the most important elements of pollution prevention programs nationwide (6).

As an alternative, formulated detergents commonly used to clean pharmaceutical, dietary supplement, and cosmetic manufacturing equipment were investigated as a low VOC, low toxicity option for cleaning cannabis and hemp extraction and process equipment.

 is commonly used to describe an aqueous-based cleaner having functional components to enhance certain mechanisms of a solution over water, solvents, or commodity cleaning agents such as sodium hydroxide alone. Because of their composition, formulated or pharmaceutical grade detergents may be more effective in cleaning a broader range of soils and products encountered in manufacturing. Certain characteristics are considered when formulating, such as analytical detection, rinsability, material compatibility, sustainability, antimicrobial effectiveness, and foam characteristics. In 

Validated Cleaning Technologies for Pharmaceutical Manufacturing

 (7), LeBlanc stated “While the cost as purchased per kilogram may be higher for the formulated cleaner, the overall process cost may be less due to time savings.”

Some progressive equipment manufacturers incorporate the ability to use formulated detergents into their equipment, such as Precision Extractions Solutions KPD Series Vulcan Industrial Extractors, which integrate a clean-in-place (CIP) skid into the extraction equipment. The skid is fitted with tanks for alkaline and acid formulated detergents as well as a reuse tank. Automated CIP systems allow for standardized cleaning processes rather than variable manual processes. 

A direct comparison was performed at a large cannabis manufacturing site where decarboxylated material was manually cleaned from equipment surfaces using ethanol. The cleaning process required an entire 8-hour shift to clean and at least two operators to perform the manual process. Stainless steel test surface coupons were prepared by coating with the product and exposing coated coupons to the same temperature and conditions as the equipment to prepare a soiled surface reflective of the manufacturing process (Figure 1). Coupons were then manually cleaned by either wiping with ethanol and rinsing with purified water or wiping with 1% formulated alkaline detergent at ambient temperature, followed by a rinse with purified water.

Coupons cleaned with ethanol and purified water displayed visible residue (Figure 2), where the coupon cleaned using formulated alkaline detergent was visibly clean (Figure 3). After a cleaning process, visual failures may lead to corrosion issues in stainless steel equipment and eventually microbial failures. Proper cleaning will minimize many common problems, including clogged lines or valves, poor separation, and low yield. If the same extractor is used to run multiple strains (such as high CBD strains and high THC strains), it is best to thoroughly clean in between extraction runs to minimize cross-contamination (8).

A dilemma facing cannabis and hemp manufacturing sites is the extended cleaning time when using a solvent system for equipment cleaning. As shown in the previous example, the use of ethanol was not effective in completely removing the residue. In moving to formulated detergents for equipment cleaning, the end-user was able to clean in a fraction of the time. Cleaning process optimization through laboratory studies to eliminate visual failures and reduce lengthy cleaning processes is described in the following case study.

A large cannabis manufacturer reported consistent visual failures as well as long cleaning times. Laboratory testing of the final product, crude extract, and decarb (herb material and biomass) material was performed at the site (Figure 4). In addition to improving the cleaning results, the site also wanted to replace ethanol with a safer, more efficient alternative.

All coupons were coated and air-dried at ambient temperature for 16 hours to simulate manufacturing dirty hold time conditions. Cleaning parameters were identified by testing various conditions through agitated immersion. A 1% v/v cleaning solution of formulated NaOH-based alkaline detergent containing sodium hydroxide at 45 °C for 20 min cleaned the final product and crude extract; however, the decarb (biomass) residue required the addition of a
detergent additive.

Comparative testing was performed on the crude product using ethanol, the manufacturing site’s current cleaning product, and a formulated alkaline detergent. The use of ethanol resulted in a significant cleaning failure, as observed on the center coupon versus passing results for the formulated alkaline detergent (Figure 5). The image on the left in Figure 5 represents crude extract material residue, the center image represents post-ethanol cleaning results, and the image on the right represents post-cleaning results using 1% v/v solution of formulated alkaline detergent containing sodium hydroxide at 45 °C for 20 min. Switching to formulated cleaners resulted in reducing the overall cleaning time and better control over their cleaning.

One of the top 10 cannabis drug manufacturers in the world wanted to determine the optimal cleaning parameters for their active pharmaceutical ingredient (API) and oil carrier excipient removal. The site visit included a laboratory-scale study (9) and an at-scale cleaning trial for a 1000 L soiled formulation vessel with a 35 L in-line API addition tank. The current cleaner, ethanol, used in the pilot-scale production area, was not scalable due to safety considerations and high disposal costs.

A laboratory evaluation was performed at the customer site (10). Coupons were coated and air-dried for 16 hours, then cleaned by agitated immersion and manual cleaning. As recommended, alkaline detergent was evaluated (we have generally recommended the same detergent for the cannabis market as it could serve as a cleaner and disinfectant) and proved effective across the board. It was recommended to use a 1% v/v alkaline detergent at 60 °C for 10 min or 2% v/v alkaline detergent at 45 °C for 10 min.

The customer developed a specific wash cycle that removed the residue from the API in the formulation tank with assistance. The site considered cleaning the API vessel out of place or use the CIP skid and connect directly to the CIP system and clean automatically using a recommended cleaning procedure. The 3% v/v alkaline detergent at 60 °C for a minimum of 10 min was recommended to clean the API vessel effectively. The 3% v/v alkaline detergent was recommended for cleaning because the decarboxylation tank has a baking step at more than 170 °C for 2 hours, creating a more challenging soil.

The field trial helped the customer drastically improve the API and formulation tank’s appearance and provide supporting data to replace ethanol as the cleaning agent for production equipment. Minor adjustments had to be made by the customer to finalize the cleaning procedure with recommended detergent.

Critical cleaning parameters have been well defined in the literature and include: time, action, cleaning chemistry, concentration, temperature, water quality, surface, soil load and condition, and environmental factors. Laboratory testing has effectively defined critical cleaning parameters for removing process residues such as cannabis (11). Laboratory testing involves applying the residue on a surface that is representative of the cannabis residues. The test continues by conditioning the applied residue on a surface to simulate the “real world” process and finally cleaning the surface to represent how the equipment is normally cleaned within the facility. Laboratory testing is described in Table I, and the acceptance criteria are described in the sidebar titled “Acceptance Criteria Used in Laboratory Testing” (12). The various cleaning factors to monitor during the laboratory testing include cleaning agent, temperature, time, action, water quality, surface material, rinsing method, and environmental factors.

Ethanol is commonly used as the cleaning agent for removing cannabis residues from the surface. Ethanol cleaning utilizes the cleaning mechanism of solubility. 

 is defined as the dissolution of one contaminant in the liquid solvent. If more than one contaminant present in the residue needs to be cleaned, then one contaminant might have a different solubility profile than another contaminant in the mix.

There are many disadvantages associated with using solvents such as ethanol. There are safety and environmental concerns such as flammability and volatile organic compound emissions, which make using these solvents undesirable.

This article proposes alternative and effective cleaning solutions for cannabis and hemp processing equipment.

September 2021

Laboratory Accreditation: Is It Enough to Guarantee Your Samples Are Analyzed Correctly?

A Closer Look at the Rise of Psychedelic Medicine and Panacea Plant Sciences

Microbiological Implications of Commercial Cannabis in Northern California: A Survey of Bacterial and Fungal Contamination

Cannabis and Hemp Tableting Challenges

An Essential Element for Commercial Cannabis and Hemp Manufacturing: Practical Cleaning Solutions for Extraction and Processing Equipment

Does Light Spectrum Alter Plant Transpiration Rates?

Cannalingo, Part I: A Guided Tour Through the Influence of Protein Structure and Function on Cannabinoid Signaling