The Basics of Cannabis QC

by | Food, Pharmaceutical

Publish Date: October 23, 2017

Every year cannabis for medical and recreational use becomes legal in more places throughout the United States. As of 2017, 29 states and the District of Columbia (DC) have passed laws to legalize growth and distribution of the plant. Cannabis is not federally regulated in the U.S. which means states opting for legalization must adopt regulations to ensure patient and user safety. This can leaf laboratories wondering how to satisfy regulatory requirements for cannabis products.

Cannabis QC Best Practices

Just like any other laboratory, priority number one for laboratories testing cannabis is to ensure the quality of the product. Best practices for cannabis quality control include:

  1. Validating methods
  2. Using proper controls
  3. Monitoring processes to prove they are working correctly
  4. Verifying technicians can effectively perform test methods by conducting routine proficiency testing (PT)

What’s lying in wait in your weed?

Laboratories are responsible for conducting tests to detect microbial impurities in cannabis. Interestingly, what is considered a “microbial impurity” differs from state to state. Some state regulations call out specific strains that cannot be present in a cannabis product, while others are more general. Although regulations vary, the top three microbial impurities all labs must test for are:

  • Yeast and mold (aflatoxin producing)
  • Shiga toxin-producing Escherichia coli (STEC)
  • Salmonella

For example, the Bureau of Marijuana Control California Code of Regulations Title 16, Division 42 Section 5316 and the Colorado Department of Health call out specific impurities including STEC, Salmonella, Aspergillus fumigatus, Aspergillus flavus, Aspergillus nigerAspergillus terreus.

Interpreting and Implementing Regulations

Every state that legalizes cannabis creates regulations stating laboratories must test and find impurities, but not all require laboratories to test for the absence of these impurities. Colorado’s regulations offer some of the most straightforward guidance. To find out how testing laboratories interpret regulations and test for impurities, I conducted an interview with a contract cannabis testing laboratory in Boulder, Colorado. Below are examples of testing methods they use to meet the requirements of Colorado regulations:

  • Yeast and mold are tested using manual methods
    • Sample matrices are spiked with an enumerated culture of yeast, homogenized and plated
    • The inoculum is run in parallel to calculate the percent recovery of yeast in the matrix
  • STEC and Salmonella are tested using molecular methods
    • Sample matrices are spiked and enriched overnight
    • The enriched samples are then tested for E. coli and Salmonella using qPCR
    • In-house developed assays or commercial test kits are available for working with a cannabis matrix and PCR
  • Each test is run with controls almost daily to prove to auditors that the methods effectively detected the presence/absence of sample impurities

This is just one example of the many methods used for detecting microbial impurities in cannabis products.  Although the methods and regulations are not harmonized, all testing laboratories share a common goal: to ensure product quality and patient safety.

Microbiologics provides the microbial controls and proficiency testing solutions your laboratory needs to maintain the highest quality standards. Choose from common proficiency testing panels or partner with us to create customized testing solutions. Visit to learn more.



Written by Kali Sorum

Kali Sorum has been a part of the Technical Support Team at Microbiologics since 2012 and has recently joined the Marketing Team as the Technical Marketing Manager. During her time at Microbiologics, she has provided technical support to Microbiologics’ customers internationally and domestically for our products used as Quality Control reference materials in various industries such as the Pharmaceutical, Food, Cosmetic and Clinical. She addresses how they are used and implemented in Quality Control testing for multiple regulations including but not limited to the USP, BAM, CLSI, FDA, and others. Other duties include investigation of product complaints, planning and executing laboratory investigations, assisting and developing training programs on the use of our products and specific test methods, as well as management of the Technical Support Team. Kali has also been a part of the Internal Audit Team since 2014. Auditing yearly to FDA Part 820, ISO 17025, ISO 13485 and ISO Guide 34 standards. She has a Bachelor of Science degree from Nebraska Wesleyan University in Biology and Pre-Pharmacy as well as a minor in Chemistry. She has been certified as a Registered Microbiologist in Pharmaceutical and Medical Device Microbiology (RM) through the National Registry of Certified Microbiologists (NCRCM) since June of 2016.

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