Tag Archives: sample

Swetha Kaul, PhD

Colorado vs. California: Two Different Approaches to Mold Testing in Cannabis

By Swetha Kaul, PhD
Swetha Kaul, PhD

Across the country, there is a patchwork of regulatory requirements that vary from state to state. Regulations focus on limiting microbial impurities (such as mold) present in cannabis in order for consumers to receive a safe product. When cultivators in Colorado and Nevada submit their cannabis product to laboratories for testing, they are striving to meet total yeast and mold count (TYMC) requirements.In a nascent industry, it is prudent for state regulators to reference specific testing methodologies so that an industry standard can be established.

TYMC refers to the number of colony forming units present per gram (CFU/g) of cannabis material tested. CFU is a method of quantifying and reporting the amount of live yeast or mold present in the cannabis material being tested. This number is determined by plating the sample, which involves spreading the sample evenly in a container like a petri dish, followed by an incubation period, which provides the ideal conditions for yeast and mold to grow and multiply. If the yeast and mold cells are efficiently distributed on a plate, it is assumed that each live cell will give rise to a single colony. Each colony produces a visible spot on the plate and this represents a single CFU. Counting the numbers of CFU gives an accurate estimate on the number of viable cells in the sample.

The plate count methodology for TYMC is standardized and widely accepted in a variety of industries including the food, cosmetic and pharmaceutical industries. The FDA has published guidelines that specify limits on total yeast and mold counts ranging from 10 to 100,000 CFU/g. In cannabis testing, a TYMC count of 10,000 is commonly used. TYMC is also approved by the AOAC for testing a variety of products, such as food and cosmetics, for yeast and mold. It is a fairly easy technique to perform requiring minimal training, and the overall cost tends to be relatively low. It can be utilized to differentiate between dead and live cells, since only viable living cells produce colonies.

Petri dish containing the fungus Aspergillus flavus
Petri dish containing the fungus Aspergillus flavus.
Photo courtesy of USDA ARS & Peggy Greb.

There is a 24 to 48-hour incubation period associated with TYMC and this impedes speed of testing. Depending on the microbial levels in a sample, additional dilution of a cannabis sample being tested may be required in order to count the cells accurately. TYMC is not species-specific, allowing this method to cover a broad range of yeast and molds, including those that are not considered harmful. Studies conducted on cannabis products have identified several harmful species of yeast and mold, including Cryptococcus, Mucor, Aspergillus, Penicillium and Botrytis Cinerea. Non-pathogenic molds have also been shown to be a source of allergic hypersensitivity reactions. The ability of TYMC to detect only viable living cells from such a broad range of yeast and mold species may be considered an advantage in the newly emerging cannabis industry.

After California voted to legalize recreational marijuana, state regulatory agencies began exploring different cannabis testing methods to implement in order to ensure clean cannabis for the large influx of consumers.

Unlike Colorado, California is considering a different route and the recently released emergency regulations require testing for specific species of Aspergillus mold (A. fumigatus, A. flavus, A. niger and A. terreus). While Aspergillus can also be cultured and plated, it is difficult to differentiate morphological characteristics of each species on a plate and the risk of misidentification is high. Therefore, positive identification would require the use of DNA-based methods such as polymerase chain reaction testing, also known as PCR. PCR is a molecular biology technique that can detect species-specific strains of mold that are considered harmful through the amplification and analysis of DNA sequences present in cannabis. The standard PCR testing method can be divided into four steps:

  1. The double stranded DNA in the cannabis sample is denatured by heat. This refers to splitting the double strand into single strands.
  2. Primers, which are short single-stranded DNA sequences, are added to align with the corresponding section of the DNA. These primers can be directly or indirectly labeled with fluorescence.
  3. DNA polymerase is introduced to extend the sequence, which results in two copies of the original double stranded DNA. DNA polymerases are enzymes that create DNA molecules by assembling nucleotides, the building blocks of DNA.
  4. Once the double stranded DNA is created, the intensity of the resulting fluorescence signal can uncover the presence of specific species of harmful Aspergillus mold, such as fumigatus.

These steps can be repeated several times to amplify a very small amount of DNA in a sample. The primers will only bind to the corresponding sequence of DNA that matches that primer and this allows PCR to be very specific.

PCR testing is used in a wide variety of applications
PCR testing is used in a wide variety of applications
Photo courtesy of USDA ARS & Peggy Greb.

PCR is a very sensitive and selective method with many applications. However, the instrumentation utilized can be very expensive, which would increase the overall cost of a compliance test. The high sensitivity of the method for the target DNA means that there are possibilities for a false positive. This has implications in the cannabis industry where samples that test positive for yeast and mold may need to go through a remediation process to kill the microbial impurities. These remediated samples may still fail a PCR-based microbial test due to the presence of the DNA. Another issue with the high selectivity of this method is that other species of potentially harmful yeast and mold would not even be detected. PCR is a technique that requires skill and training to perform and this, in turn, adds to the high overall cost of the test.

Both TYMC and PCR have associated advantages and disadvantages and it is important to take into account the cost, speed, selectivity, and sensitivity of each method. The differences between the two methodologies would lead to a large disparity in testing standards amongst labs in different states. In a nascent industry, it is prudent for state regulators to reference specific testing methodologies so that an industry standard can be established.

dSPE cleanups

The Grass Isn’t Always Greener: Removal of Purple Pigmentation from Cannabis

By Danielle Mackowsky
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dSPE cleanups
Cannabis strains used (clockwise from top left): Agent Orange, Tahoe OG, Blue Skunk, Grand Daddy and Grape Drink

Cannabis-testing laboratories have the challenge of removing a variety of unwanted matrix components from plant material prior to running extracts on their LC-MS/MS or GC-MS. The complexity of the cannabis plant presents additional analytical challenges that do not need to be accounted for in other agricultural products. Up to a third of the overall mass of cannabis seed, half of usable flower and nearly all extracts can be contributed to essential oils such as terpenes, flavonoids and actual cannabinoid content1. The biodiversity of this plant is exhibited in the over 2,000 unique strains that have been identified, each with their own pigmentation, cannabinoid profile and overall suggested medicinal use2. While novel methods have been developed for the removal of chlorophyll, few, if any, sample preparation methods have been devoted to removal of other colored pigments from cannabis.

Cannabis samples following QuEChERS extraction

Sample Preparation

Cannabis samples from four strains of plant (Purple Drink, Tahoe OG, Grand Daddy and Agent Orange) were hydrated using deionized water. Following the addition of 10 mL acetonitrile, samples were homogenized using a SPEX Geno/Grinder and stainless steel grinding balls. QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe) non-buffered extraction salts were then added and samples were shaken. Following centrifugation, an aliquot of the supernatant was transferred to various blends of dispersive SPE (dSPE) salts packed into centrifugation tubes. All dSPE tubes were vortexed prior to being centrifuged. Resulting supernatant was transferred to clear auto sampler vials for visual analysis. Recoveries of 48 pesticides and four mycotoxins were determined for the two dSPE blends that provided the most pigmentation removal.

Seven dSPE blends were evaluated for their ability to remove both chlorophyll and purple pigmentation from cannabis plant material:

  • 150 mg MgSO4, 50 mg PSA, 50 mg C18, 50 mg Chlorofiltr®
  • 150 mg MgSO4, 50 mg C18, 50 mg Chlorofiltr®
  • 150 mg MgSO4, 50 mg PSA
  • 150 mg MgSO4, 25 mg C18
  • 150 mg MgSO4, 50 mg PSA, 50 mg C18
  • 150 mg MgSO4, 25 mg PSA, 7.5 mg GCB
  • 150 mg MgSO4, 50 mg PSA, 50 mg C18, 50 mg GCB

Based on the coloration of the resulting extracts, blends A, F and G were determined to be the most effective in removing both chlorophyll (all cannabis strains) and purple pigments (Purple Drink and Grand Daddy). Previous research regarding the ability of large quantities of GCB to retain planar pesticides allowed for the exclusion of blend G from further analyte quantitation3. The recoveries of the 48 selected pesticides and four mycotoxins for blends A and F were determined.

dSPE cleanups
Grand Daddy following various dSPE cleanups


A blend of MgSO4, C18, PSA and Chlorofiltr® allowed for the most sample clean up, without loss of pesticides and mycotoxins, for all cannabis samples tested. Average recovery of the 47 pesticides and five mycotoxins using the selected dSPE blend was 75.6% were as the average recovery when including GCB instead of Chlorofiltr® was 67.6%. Regardless of the sample’s original pigmentation, this blend successfully removed both chlorophyll and purple hues from all strains tested. The other six dSPE blends evaluated were unable to provide the sample clean up needed or had previously demonstrated to be detrimental to the recovery of pesticides routinely analyzed in cannabis.


(1)           Recommended methods for the identification and analysis of cannabis and cannabis products, United Nations Office of Drugs and Crime (2009)

(2)            W. Ross, Newsweek, (2016)

(3)            Koesukwiwat, Urairat, et al. “High Throughput Analysis of 150 Pesticides in Fruits and Vegetables Using QuEChERS and Low-Pressure Gas Chromatography Time-of-Flight Mass Spectrometry.” Journal of Chromatography A, vol. 1217, no. 43, 2010, pp. 6692–6703., doi:10.1016/j.chroma.2010.05.012.

Sunrise Genetics Partners With RPC, Begins Genetic Testing in Canada

By Aaron G. Biros
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Sunrise Genetics, Inc., the parent company of Marigene and Hempgene, announced their partnership with New Brunswick Research & Productivity Council (RPC) this week, according to a press release. The company has been working in the United States for a few years now doing genomic sequencing and genetic research with headquarters based in Fort Collins, CO. This new partnership, compliant with Health Canada sample submission requirements, allows Canadian growers to submit plants for DNA extraction and genomic sequencing.

Sunrise Genetics researches different cannabis cultivars in the areas of target improvement of desired traits, accelerated breeding and expanding the knowledge base of cannabis genetics. One area they have been working on is genetic plant identification, which uses the plant’s DNA and modern genomics to create authentic, reproducible, commercial-ready strains.

Matt Gibbs, president of Sunrise Genetics, says he is very excited to get working on cannabis DNA testing in Canada. “RPC has a long track record of leadership in analytical services, especially as it relates to DNA and forensic work, giving Canadian growers their first real option to submit their plant samples for DNA extraction through proper legal channels,” says Gibbs. “The option to pursue genomic research on cannabis is now at Canadian cultivator’s fingertips.”

Canada’s massive new cannabis industry, which now has legal recreational and medical use, sales and cultivation, previously has not had many options for genetic testing. Using their genetic testing capabilities, they hope this partnership will better help Canadian cultivators easily apply genomic testing for improved plant development. “I’m looking forward to working with more Canadian cultivators and breeders; the opportunity to apply genomics to plant improvement is a win-win for customers seeking transparency about their Cannabis product and producers seeking customer retention through ‘best-in-class’ cannabis and protectable plant varieties,” says Gibbs. The partnership also ensures samples will follow the required submission process for analytical testing, but adding the service option of genetic testing so growers can find out more about their plants beyond the regular gamut of tests.

RPC is a New Brunswick provincial research organization (PRO), a research and technology organization (RTO) that offers R&D testing and technical services. With 130 scientists, engineers and technologists, RPC offers a wide variety of testing services, including air quality, analytical chemistry of cannabis, material testing and a large variety of pilot facilities for manufacturing research and development.

They have over 100 accreditations and certifications including an ISO 17025 scope from the Standards Council of Canada (SCC) and is ISO 9001:2008 certified. This genetic testing service for cannabis plants is the latest development in their repertoire of services. “This service builds on RPC’s established genetic strengths and complements the services we are currently offering the cannabis industry,” says Eric Cook, chief executive officer of RPC.

Using Cloud-Based LIMS To Improve Efficiency In Cannabis Labs

By Shonali Paul
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Cannabis testing laboratories around the country are expanding quickly, taking on new clients and growing their business incrementally. Many of these labs are receiving a large number of test requests from growers for potency testing, terpene profiling, pesticide screening, residual solvent screening, heavy metal testing, microbial analysis and even genetic testing. To keep pace with the number of test requests received, efficient data, sample and test management is imperative.

Considering the magnitude of cannabis testing, data management using spreadsheets is a serious impediment to quality assurance. Data being recorded in spreadsheets is error-prone and difficult to manage. Furthermore, using spreadsheets does not allow labs to adhere to regulatory guidelines that demand strict accounting for every gram of the sample, right from reception, consumption for testing, to disposal.

Log samples, keep track of Chain of Custody(CoC), track samples from initial location in the lab through disposal by recording location, custodians and other metadata

To overcome such data management challenges and improve the operational efficiency of cannabis testing laboratories, a Laboratory Information Management System (LIMS) plays a significant role. LIMS are much more capable than spreadsheets and paper-based tools for managing analytical and operational activities. LIMS enhances the productivity and quality by eliminating the manual data entry. With its built-in audit trail capability, LIMS helps labs adhere to regulatory standards.

LIMS can provide companies with a method to manage samples, records and test results, and ensures regulatory compliance by increasing traceability. LIMS can also be integrated with other lab instrumentation and enterprise systems, enabling easier transmission of information across the lab and the organization, reducing manual efforts and improving decision-making.

Account for the entire quantity of sample received, used and disposed

Multiple resources are also available to assist labs in preparing for quality assurance and accreditation, LIMS being one of them. LIMS can help cannabis labs with instrument integration, and automate reporting to help improve efficiencies and reduce errors. LIMS, such as CloudLIMS Lite, a cloud-based LIMS, automates cannabis-testing workflows right from sample collection, data recording, managing test chain of custody, sample weight accounting to report generation. With data security and audit trails, a LIMS provides traceable documentary evidence required to achieve ISO 17025 accreditation for highly regulated labs. Above all, cloud-enabled systems are often low in the total cost of acquisition, have maintenance outsourced, and are scalable to help meet the ever-changing business and regulatory compliance needs.

Incorporate all tests, instruments, sample information and result data (etc.) in one place

Cloud-based products are secure, easy to deploy and scalable. A cloud product is typically hosted on a server with a guaranteed uptime of 99.5%, allowing for a reliable system, accessible 24×7. Cloud-based LIMS have automatic data backup mechanism that allow for quick turnarounds in case of a server failure or in the eventuality of a natural disaster.

With LIMS in place, cannabis labs can manage sample and requisition-centric records, track sample quantity and location, integrate the test data, and provide online reports to clients. This in turn, reduces the turnaround time for testing and improves the operational efficiency. Besides, audit trail of each and every activity performed by the lab personnel is recorded in the system to ensure that the lab follows regulatory compliance.

Editor’s Note: This is a condensed version of a poster that was submitted and displayed at this year’s Cannabis Science Conference in Portland, Oregon. The authors of the original poster are Arun Apte, Stephen Goldman, Aditi Gade and Shonali Paul.

JCanna Boot Camp Educates Portland Attendees

By Aaron G. Biros
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On Monday, August 28th, attendees of the Cannabis Science Conference descended on Portland, Oregon for a week of educational talks, networking and studying the science of cannabis. On Monday, Chalice Farms, an extracts and infused products company, hosted the full-day JCanna Boot Camp focused on a deep dive behind the scenes of a cannabis production facility. The Cannabis Science Conference, hosted by Josh Crossney, founder of JCanna, takes place August 28th to 30th.

Attendees touring an extraction setup

Attendees were split into five groups where they listened to a variety of educational sessions and toured the facility. A track focused on cultivation, led by Autumn Karcey, president of Cultivo, Inc., detailed all things facility design for cannabis cultivation, including an in-depth look at sanitation and safety. For example, Karcey discussed HVAC cleanliness, floor-to-ceiling sanitation and the hazards associated with negative pressure. These principles, while applicable to most cultivating facilities, applies particularly to commercial-scale grows in a pharmaceutical setting.

Sandy Mangan and Tristan DeBona demonstrating the grinding technique for sample prep

During one session, Sandy Mangan, accounts manager at SPEX Sample Prep and Tristan DeBona, sales specialist at SPEX Sample Prep, demonstrated the basics of sample preparation for detecting pesticides in infused products, such as gummies. That required using their GenoGrinder and FreezerMill, which uses liquid nitrogen to make gummies brittle, then pulverizing them to a powder-like substance that is more conducive for a QuEChERS preparation.

Joe Konschnik and Susan Steinike demonstrate the QuEChERS method

Joe Konschnik, business development manager at Restek, Susan Steinike, product-marketing manager at Restek and Justin Steimling, an analytical chemist at Restek, gave a demonstration of a full QuEChERS extraction of a cannabis sample for pesticide analysis, with attendees participating to learn the basics of sample preparation for these types of tests.

Following those were some other notable talks, including a tour of the extraction instruments and equipment at Chalice Farms, a look inside their commercial kitchen and a discussion of edibles and product formulation. Dr. Uma Dhanabalan, founder of Uplifting Health and Wellness, a physician with over 30 years of experience in research and patient care, led a discussion of physician participation, patient education and drug delivery mechanisms.

Amanda Rigdon, Emerald Scientific, showing some complex matrices in cannabis products

Amanda Rigdon, chief technical officer of Emerald Scientific, offered a demonstration of easy and adaptable sample preparation techniques for potency testing of infused product matrices. Rigdon showed attendees of the boot camp how wildly diverse cannabis products are and how challenging it can be for labs to test them.

The JCanna Canna Boot Camp is a good example of an educational event catered to the cannabis industry that offers real, hands-on experience and actionable advice. Before the two-day conference this week, the boot camp provided a bird’s eye view for attendees of the science of cannabis.

Judging a Craft Cannabis Competition

By Aaron G. Biros
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Willamette Week, a Portland-based publication, is hosting the 2017 Cultivation Classic with Farma, Cascadia Labs, Phylos Bioscience and the Resource Innovation Institute on May 12th. The event is a benefit for the Ethical Cannabis Alliance, an organization that promotes sustainability, labor standards and education surrounding the integrity and ethics of growing cannabis. Cultivation Classic is a competition for pesticide-free cannabis grown in Oregon, according to a press release.

Congressman Earl Blumenauer speaking at last year’s Cultivation Classic
Photo: Bridget Baker, 92bridges.com

While the event’s focus is on the competition, it is just as much a celebration of the craft cannabis community in Oregon. This year’s competition incorporates scientific collaboration like genetic sequencing for the winners by Phylos Bioscience and carbon accounting for all competitors. Keynote speakers include Ethan Russo, medical director of PHYTECS and Dr. Adie Po, co-founder of Habu Health. Congressman Earl Blumenauer, a prominent cannabis legalization advocate in Oregon, will also be speaking at the awards ceremony. You can check out the full schedule and speaker lineup here.

Raymond Bowser, breeder at Home Grown Natural Wonders, is a judge for this year’s Cultivation Classic. He speaks at cannabis conferences around the country and his business created a number of different strains, so he has experience with a myriad of growers and strains. “This time around everyone has really stepped up their game,” says Bowser. “The entries are noticeably better than last year.” When looking at the different samples sent to him, he sees a few key factors as most important in judging the quality. “What I am looking for is simple; a nice smell and a decent look, generally speaking,” says Bowser. “Aesthetics can tell you a lot about how it was grown, temperature changes and the overall care taken in cultivating and curing the flower.” For him, flavor, smell and aesthetics are the big variables to consider.

Photo: Bridget Baker, 92bridges.com

Those are factors that his company holds to high standards in their work, so he judges the samples based on the same variables. “It is what we strive for in our gardens and so far the samples I have tried are fantastic in that regard,” says Bowser. In other competitions that Bowser has judged in the past, they sent him between 40 and 60 strains to judge in seven days. “That is not conducive to a fair evaluation,” says Bowser. “Here, we are getting fourteen or so different strains, so we can sample one strain a day which is how I personally like to do it.”

Bowser is supportive of Cultivation Classic because of their emphasis on the craft industry. “We talk about craft cannabis and breeding craft cultivars at conferences around the country,” says Bowser. “With the rec industry growing so much, we see so many people cutting corners to save money, that it is refreshing to see growers take pride in the craft.” He also stresses the need for good lab testing and sound science in the trade. “I am big on lab testing; it is very important to get all the right analytics when creating strains,” says Bowser. “Cascadia is a solid choice for the competition; they have been a very good, consistent lab.” Emphasizing the local, sustainability-oriented culture surrounding the craft market, Bowser is pleased that this competition supports that same message. “We need to stay true to our Oregon roots and continue to be a clean, green, granola-eating state.”

Photo: Bridget Baker, 92bridges.com

Cascadia Labs is conducting the pesticide and cannabinoid analytics for all submissions and Phylos Bioscience will perform testing for the winners. According to Julie Austin, operations manager at Cascadia Labs, pesticide testing for the Oregon list of analytes was of course a requirement. “Some of the samples submitted had previous tests from us or from other accredited labs, but if they didn’t have those results we did offer a comprehensive pesticide test,” says Austin. The competition’s fee for submission includes the potency and terpenes analysis.

Jeremy Sackett, director of operations at Cascadia Labs, says they test for 11 cannabinoids and 21 terpenes. The samples are divided into groups of THC-dominant samples, CBD-dominant samples and samples with a 1:1 ratio of the two. “The actual potency data will be withheld from judges and competitors until the day of the event,” says Sackett. “We are data driven scientists, but this time we want to have a little fun and bring the heart of this competition back to the good old days: when quality cannabis was gauged by an experience of the senses, not the highest potency number.” The event will take place on May 12th at Revolution Hall in Portland, Oregon. Click here to get tickets to the event.

Annual AOCS Meeting Spotlights Cannabinoid Analytics

By Aaron G. Biros
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The AOCS Annual Meeting is an international science and business forum on fats, oils, surfactants, lipids and related materials. The American Oil Chemist’s Society (AOCS) is holding their meeting in Orlando, Florida from April 30 to May 3, 2017. Last year’s meeting included discussions on best practices and the pros and cons of different extraction techniques, sample preparation, proficiency testing and method development, among other topic areas.

Posters on display for the duration of the Annual Meeting will discuss innovative solutions to test, preparing samples, discovering new compounds and provide novel information about the compounds found in cannabis. David Egerton, vice president of technical operations at CW Analytical (a cannabis testing laboratory in Oakland, CA), is preparing a poster titled Endogenous Solvents in Cannabis Extracts. His abstract discusses testing regulations focusing on the detection of the presence of solvents, despite the fact that endogenous solvents, like acetone and lower alcohols, can be found in all plant material. His study will demonstrate the prevalence of those compounds in both the plant material and the concentrated oil without those compounds being used in production.rsz_am17-editorialpic-cij

The conference features more than 650 oral and poster presentations within 12 interest areas. This year’s technical program includes two sessions specifically designed to address cannabinoid analytics:

Lab Proficiency Programs and Reference Samples

How do you run a lab proficiency program when you cannot send your samples across state lines? What constituents do you test for when state requirements are all different? Are all pesticides illegal to use on cannabis? What pesticides should be tested for when they are mostly illegal to use? How do you analyze proficiency results when there are no standard methods? Learn about these and other challenges facing the cannabis industry. This session encourages open and active discussion, as the cannabis experts want to hear from you and learn about your experiences.

Method Development

The need for high-quality and safe products has spurred a new interest in cannabinoid analytics, including sample preparation, pesticide, and other constituent testing. In this session, a diverse group of scientists will discuss developing analytical methods to investigate cannabis. Learn the latest in finding and identifying terpenes, cannabinoids, matrix effects, and even the best practice for dissolving a gummy bear.

Cynthia Ludwig speaking at last year's meeting
Cynthia Ludwig speaking at last year’s meeting

Cynthia Ludwig, director of technical services at AOCS, says they are making great progress in assembling analytical methods for the production of the book AOCS Collection of Cannabis Analytical Methods. “We are the leading organization supporting the development of analytical methods in the cannabis industry,” says Ludwig. “Many of the contributors in that collection will be presenting at the AOCS Annual Meeting, highlighting some of the latest advances in analyzing cannabis.” The organization hopes to foster more collaboration among those in the cannabis testing industry.

In addition to oral and poster sessions, the 2017 Annual Meeting will feature daily networking activities, more than 70 international exhibitors, two special sessions, and a Hot Topics Symposia which will address how current, critical issues impact the future of the fats and oils industry.

Colorado Cannabis Lab Methods Updated for Microbial Testing

By Aaron G. Biros
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The Colorado Department of Public Health and Environment’s (CDPHE) Marijuana Laboratory Inspection Program issued a bulletin on January 30th regarding updates required for licensed cannabis testing labs. The updated method for microbial contaminant testing includes a longer incubation period in yeast and mold testing.BannerForEnf

“After careful consideration of emerging data regarding the use and effectiveness of 3M Total Yeast and Mold Rapid Petrifilms in marijuana, CDPHE has concluded that 48 hours is not a sufficient incubation period to obtain accurate results,” the letter states. “Based upon the review of this information, marijuana/marijuana products require 60-72 hours of incubation as per the manufacturer’s product instructions for human food products, animal feed and environmental products.” The letter says they determined it was necessary to increase the incubation period based on data submitted from several labs, along with a paper found in the Journal of Food Protection.

An incubator (Right) at TEQ Analytical Labs
An incubator (Right) at TEQ Analytical Labs

According to Alexandra Tudor, manager of the microbiology department at TEQ Analytical Labs (a cannabis testing lab in Aurora, CO), the update is absolutely necessary. “The incubation time extension requirement from CDPHE offers more reliable and robust data to clients by ruling out the possibility of a false yeast and mold result during analysis,” says Tudor.

Alexandra Tudor, microbiology department manager at TEQ Analytical Labs
Alexandra Tudor, microbiology department manager at TEQ Analytical Labs

“3M, the maker of Petrifilm, recommends an incubation time of 48-72 hours, but during TEQ’s method validation procedure, we learned that 48-hour incubation was not sufficient time to ensure accurate results. Although some laboratories in industry had been incubating for the minimum amount of time recommended by the manufacturer, the 48-hour incubation time does not provide a long enough window to ensure accurate detection of microbiological contaminants present in the sample.” Tudor says the update will help labs provide more confident results to clients, promoting public health sand safety.IMG_6386-2

As a result of the update in testing methodology, cultivators and infused product manufacturers in Colorado need to submit a batch test for yeast and mold. The point of requiring this batch test is to determine if the producer’s process validation is still effective, given the new yeast and mold testing method.

The Nerd Perspective

Pesticide Detection in Cannabis: Lab Challenges and Why Less Isn’t Always More

By Amanda Rigdon

Almost as soon as cannabis became recreationally legal, the public started to ask questions about the safety of products being offered by dispensaries – especially in terms of pesticide contamination. As we can see from the multiple recalls of product there is a big problem with pesticides in cannabis that could pose a danger to consumers. While The Nerd Perspective is grounded firmly in science and fact, the purpose of this column is to share my insights into the cannabis industry based on my years of experience with multiple regulated industries with the goal of helping the cannabis industry mature using lessons learned from other established markets. In this article, we’ll take a look at some unique challenges facing cannabis testing labs, what they’re doing to respond to the challenges, and how that can affect the cannabis industry as a whole.

Photo: Michelle Tribe, Flickr
Photo: Michelle Tribe, Flickr

The Big Challenge

Over the past several years, laboratories have quickly ‘grown up’ in terms of technology and expertise, improving their methods for pesticide detection to improve data quality and lower detection limits, which ultimately ensures a safer product by improving identification of contaminated product. But even though cannabis laboratories are maturing, they’re maturing in an environment far different than labs from regulated industry, like food laboratories. Food safety testing laboratories have been governmentally regulated and funded from almost the very beginning, allowing them some financial breathing room to set up their operation, and ensuring they won’t be penalized for failing samples. In contrast, testing fees for cannabis labs are paid for by growers and producers – many of whom are just starting their own business and short of cash. This creates fierce competition between cannabis laboratories in terms of testing cost and turnaround time. One similarity that the cannabis industry shares with the food industry is consumer and regulatory demand for safe product. This demand requires laboratories to invest in instrumentation and personnel to ensure generation of quality data. In short, the two major demands placed on cannabis laboratories are low cost and scientific excellence. As a chemist with years of experience, scientific excellence isn’t cheap, thus cannabis laboratories are stuck between a rock and a hard place and are feeling the squeeze.

Responding to the Challenge

One way for high-quality laboratories to win business is to tout their investment in technology and the sophistication of their methods; they’re selling their science, a practice I stand behind completely. However, due to the fierce competition between labs, some laboratories have oversold their science by using terms like ‘lethal’ or ‘toxic’ juxtaposed with vague statements regarding the discovery of pesticides in cannabis using the highly technical methods that they offer. This juxtaposition can then be reinforced by overstating the importance of ultra-low detection levels outside of any regulatory context. For example, a claim stating that detecting pesticides at the parts per trillion level (ppt) will better ensure consumer safety than methods run by other labs that only detect pesticides at concentrations at parts per billion (ppb) concentrations is a potentially dangerous claim in that it could cause future problems for the cannabis industry as a whole. In short, while accurately identifying contaminated samples versus clean samples is indeed a good thing, sometimes less isn’t more, bringing us to the second half of the title of this article.

Less isn’t always more…

Spiral Galaxy Milky Way
The Milky Way

In my last article, I illustrated the concept of the trace concentrations laboratories detect, finishing up with putting the concept of ppb into perspective. I wasn’t even going to try to illustrate parts per trillion. Parts per trillion is one thousand times less concentrated than parts per billion. To put ppt into perspective, we can’t work with water like I did in my previous article; we have to channel Neil deGrasse Tyson.

The Milky Way galaxy contains about 100 billion stars, and our sun is one of them. Our lonely sun, in the vastness of our galaxy, where light itself takes 100,000 years to traverse, represents a concentration of 10 ppt. On the surface, detecting galactically-low levels of contaminants sounds wonderful. Pesticides are indeed lethal chemicals, and their byproducts are often lethal or carcinogenic as well. From the consumer perspective, we want everything we put in our bodies free of harmful chemicals. Looking at consumer products from The Nerd Perspective, however, the previous sentence changes quite a bit. To be clear, nobody – nerds included – wants food or medicine that will poison them. But let’s explore the gap between ‘poison’ and ‘reality’, and why that gap matters.

FDAIn reality, according to a study conducted by the FDA in 2011, roughly 37.5% of the food we consume every day – including meat, fish, and grains – is contaminated with pesticides. Is that a good thing? No, of course it isn’t. It’s not ideal to put anything into our bodies that has been contaminated with the byproducts of human habitation. However, the FDA, EPA, and other governmental agencies have worked for decades on toxicological, ecological, and environmental studies devoted to determining what levels of these toxic chemicals actually have the potential to cause harm to humans. Rather than discuss whether or not any level is acceptable, let’s take it on principle that we won’t drop over dead from a lethal dose of pesticides after eating a salad and instead take a look at the levels the FDA deem ‘acceptable’ for food products. In their 2011 study, the FDA states that “Tolerance levels generally range from 0.1 to 50 parts per million (ppm). Residues present at 0.01 ppm and above are usually measurable; however, for individual pesticides, this limit may range from 0.005 to 1 ppm.” Putting those terms into parts per trillion means that most tolerable levels range from 100,000 to 50,000,000 ppt and the lower limit of ‘usually measurable’ is 10,000 ppt. For the food we eat and feed to our children, levels in parts per trillion are not even discussed because they’re not relevant.

green apple with slice isolated on the white background.

A specific example of this is arsenic. Everyone knows arsenic is very toxic. However, trace levels of arsenic naturally occur in the environment, and until 2004, arsenic was widely used to protect pressure-treated wood from termite damage. Because of the use of arsenic on wood and other arsenic containing pesticides, much of our soil and water now contains some arsenic, which ends up in apples and other produce. These apples get turned into juice, which is freely given to toddlers everywhere. Why, then, has there not an infant mortality catastrophe? Because even though the arsenic was there (and still is), it wasn’t present at levels that were harmful. In 2013, the FDA published draft guidance stating that the permissible level of arsenic in apple juice was 10 parts per billion (ppb) – 10,000 parts per trillion. None of us would think twice about offering apple juice to our child, and we don’t have to…because the dose makes the poison.

How Does This Relate to the Cannabis Industry?

The concept of permissible exposure levels (a.k.a. maximum residue limits) is an important concept that’s understood by laboratories, but is not always considered by the public and the regulators tasked with ensuring cannabis consumer safety. As scientists, it is our job not to misrepresent the impact of our methods or the danger of cannabis contaminants. We cannot understate the danger of these toxins, nor should we overstate their danger. In overstating the danger of these toxins, we indirectly pressure regulators to establish ridiculously low limits for contaminants. Lower limits always require the use of newer testing technologies, higher levels of technical expertise, and more complicated methods. All of this translates to increased testing costs – costs that are then passed on to growers, producers, and consumers. I don’t envy the regulators in the cannabis industry. Like the labs in the cannabis industry, they’re also stuck between a rock and a hard place: stuck between consumers demanding a safe product and producers demanding low-cost testing. As scientists, let’s help them out by focusing our discussion on the real consumer safety issues that are present in this market.

*average of domestic food (39.5% contaminated) and imported food (35.5% contaminated)

OHA Addresses Oregon Growing Pains, Changes Testing Rules

By Aaron G. Biros
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Last week, the Oregon Health Authority (OHA) published a bulletin, outlining new temporary testing requirements effective immediately until May 30th of next year. The changes to the rules come in the wake of product shortages, higher prices and even some claims of cultivators reverting back to the black market to stay afloat.img_6245

According to the bulletin, these temporary regulations are meant to still protect public health and safety, but are “aimed at lowering the testing burden for producers and processors based on concerns and input from the marijuana industry.” The temporary rules, applying to both medical and retail products, are a Band-Aid fix while the OHA works on a permanent solution to the testing backlog.

Here are some key takeaways from the rule changes:


  • THC and CBD amounts on the label must be the value calculated by a laboratory, plus or minus 5%.

Batch testing

  • A harvest lot can include more than one strain.
  • Cannabis harvested within a 48-hour period, using the same growing and curing processes can be included in one harvest lot.
  • Edibles processors can include up to 1000 units of product in a batch for testing.
  • The size of a process lot submitted for testing for concentrates, extracts or other non-edible products will be the maximum size for future sampling and testing.

    Oregon Marijuana Universal Symbol for Printing
    Oregon Marijuana Universal Symbol for Printing


  • Different batches of the same strain can be combined for testing potency.
  • Samples can be combined from a number of batches in a harvest lot for pesticide testing if the weight of all the batches doesn’t exceed ten pounds. This also means that if that combined sample fails a pesticide test, all of the batches fail the test and need to be disposed.

Solvent testing

  • Butanol, Propanol and Ethanol are no longer on the solvent list.

Potency testing

  • The maximum concentration limit for THC and CBD testing can have up to a 5% variance.

Control Study

  • Process validation is replaced by one control study.
  • After OHA has certified a control study, it is valid for a year unless there is an SOP or ingredient change.
  • During the control study, sample increments are tested separately for homogeneity across batches, but when the control study is certified, sample increments can be combined.

Failing a test

  • Test reports must clearly show if a test fails or passes.
  • Producers can request a reanalysis after a failed test no later than a week after receiving failed test results and that reanalysis must happen within 30 days.
Gov. Kate Brown Photo: Oregon Dept. of Transportation
Gov. Kate Brown
Photo: Oregon Dept. of Transportation

The office of Gov. Kate Brown along with the OHA, Oregon Department of Agriculture (ODA) and Oregon Liquor Control Commission (OLCC) issued a letter in late November, serving as a reminder of the regulations regarding pesticide use and testing. It says in bold that it is illegal to use any pesticide not on the ODA’s cannabis and pesticide guide list. The letter states that failed pesticide tests are referred to ODA for investigation, which means producers that fail those tests could face punitive measures such as fines.

Photo: Michelle Tribe, Flickr
Photo: Michelle Tribe, Flickr

The letter also clarifies a major part of the pesticide rules involving the action level, or the measured amount of pesticides in a product that the OHA deems potentially dangerous. “Despite cannabis producers receiving test results below OHA pesticide action levels for cannabis (set in OHA rule), producers may still be in violation of the Oregon Pesticide Control Act if any levels of illegal pesticides are detected.” This is crucial information for producers who might have phased out use of pesticides in the past or might have began operations in a facility where pesticides were used previously. A laboratory detecting even a trace amount in the parts-per-billion range of banned pesticides, like Myclobutanil, would mean the producer is in violation of the Pesticide Control Act and could face thousands of dollars in fines. The approved pesticides on the list are generally intended for food products, exempt from a tolerance and are considered low risk.

As regulators work to accredit more laboratories and flesh out issues with the industry, Oregon’s cannabis market enters a period of marked uncertainty.