Quality Control in the World of Cannabis

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Cannabis Science and Technology, September/October 2019, Volume 2, Issue 5

This article covers the importance of quality control, how to implement it, and what cannabis cultivators, processors, retailers, and consumers should look for on laboratory reports and certificates of analysis.

The cannabis industry is an emerging field with many unknowns. With unknowns comes uncertainty, and in a world where cannabis is attempting to break the negative stigmatism which it has been given, that uncertainty can be dangerous. Cannabis, whether for medicinal or recreational use, has testing requirements that it must meet, however, until recently most states have not required quality control to support independent laboratory testing results. Strict quality control requirements should have been mandated in all legal markets years ago, being that it is essential for validating testing results. Laboratories who are responsible for testing cannabis, no matter the matrix, should be required to run quality control to show that their results are reproducible, reliable, and defensible. This article covers the importance of quality control, how to implement it, and what cannabis cultivators, processors, retailers, and consumers should look for on laboratory reports and certificates of analysis.

Quality control practices should be the backbone of any analytical laboratory. However, because cannabis testing is still considered a relatively new analytical service, many inexperienced laboratories who do not implement quality control practices still exist. This will change as the industry matures and as more rules regarding quality control continue to be implemented. The environmental industry provides an excellent example of how analytical laboratories should implement quality control practices and what requirements are expected. In some states such as New York, Texas, and Florida, the National Environmental Laboratory Accreditation (NELAC) Institute (TNI) has a set of rules and standards which laboratories must abide by; these rules are laid out in “TNI Standard – Environmental Laboratory Sector” (1). Many of the requirements outlined in the TNI document are adapted from the widely known International Organization for Standardization and the International Electrotechnical Commission (ISO/IEC) 17025 standard (2). Both of these standards outline the requirements for developing and implementing a quality system.

With the rapid increase in the number of states legalizing either medicinal or recreational cannabis, steps need to be taken to ensure that the laboratories analyzing cannabis products are producing reliable data. Before laboratories start processing samples, they should develop a quality system that ensures they are qualified to be performing the analytical analyses which they are reporting results for. The minimum requirement for certification among cannabis laboratories should be ISO/IEC 17025:2017. This standard provides thorough and concise rules and regulations for analytical laboratories. Before creating standard operating procedures, validating methodologies, and performing analyses, laboratories should first develop an ISO/IEC approved quality system. This will ensure that any practices developed from that point on will have a solid foundation to be built from.

Building a quality system requires a significant amount of time and effort. A great amount of forethought must be considered when developing this system because it will be the basis of all procedures that are carried out through the laboratory. Per ISO/IEC 17025:2017, a “laboratory shall establish, document, implement, and maintain a management system that is capable of supporting and demonstrating consistent achievement of the requirements of this document and assuring the quality of laboratory results” (2). A cannabis laboratory should develop their quality systems based on the information required by Option A within the document, which includes “addressing at a minimum: management system documentation; control of management system documents; control of records; actions to address risk and opportunities; improvement; corrective actions; internal audits; and management reviews.” By doing this, the laboratory will be able to show competence in their abilities to perform analyses that are developed under this system. By creating a standard across the board that all analytical cannabis laboratories should follow, such as ISO/IEC 17025:2017, the industry will be able to take steps towards standardizing the results that are obtained from laboratory to laboratory.

Once a quality system has been established, quality control requirements and guidelines can be outlined within the system. ISO/IEC 17025:2017 “Section 7.2 – Selection, Verification and Validation of Methods” outlines the requirements that laboratories should follow when developing or implementing any analytical method. Currently, there are no standard methodologies that all cannabis laboratories must follow when processing samples, and though this is a bigger issue that also needs to be resolved, one way to limit variability in data across laboratories is to require that these standards are followed. By doing this, method validation for the analyses being performed by the laboratory will become a requirement. After methodology is properly validated and a standard operating procedure has been established, the laboratory should then begin processing samples for that analysis.

At this point, the laboratory should implement standard quality control with each sample batch that is processed. This quality control validates the results and shows that the laboratory is able to perform the analyses with accuracy and precision. Currently, there is no set quality control required for analytical cannabis laboratories across the board. However, some states are implementing guidelines that outline requirements for quality control. Florida, for example, has included Standards for Marijuana Testing Laboratories as part of the draft for “Rule 64-4.0XX” which will fall under “64-4.016 – Marijuana Testing Laboratories” (3,4). This rule outlines all of the quality control that must be included with each batch of processed samples. The basis of quality control falls on the fact that the “quality control samples shall be analyzed in the same manner as test samples for validation purposes.” This rule ensures that the samples and the quality control are treated the same and taken through the entire process from start to finish. Currently, the draft rule for Florida states that all batches analyzed should include a method blank, laboratory fortified blank, matrix spike, laboratory fortified blank duplicate, and a matrix spike duplicate. Though the requirements may change before a final rule is issued, it is a starting point for ensuring the validity of data being produced by cannabis testing laboratories within the state.

All states that have legalized cannabis for medicinal or recreational purposes should implement rules which require quality control to be processed by any laboratory analyzing cannabis material or products. These rules should specifically outline what quality control is required but should also outline the acceptable ranges of recovery and relative percent differences that are allowed between samples. This alone will help decrease the variability in results among laboratories because all of the steps mentioned previously-including the development of a quality system, method validation, and implementation of standard operating procedures-will all precede the proper execution of batch quality control.


Each method used to quantify a set group of analytes (such as cannabinoids, terpenes, residual solvents, and so forth) have their limitations. These limitations can be unique to the analyte being tested because of their individual chemical structure and their varying interactions. In the environmental industry, the U.S. Environmental Protection Agency (EPA) outlines the recovery limitations for analytes within each method. For volatile organic compounds, EPA Method 8260B (5), the acceptable ranges vary between analytes. For example, in this method, acetone is considered a poor purging compound and therefore the recovery limits are not as stringent for it as they are for others. The same concept should be applied to the cannabis industry, however, there is currently not a sufficient amount of data available to determine what these recovery limits should be. To successfully determine what the values of recovery for analytes should be, studies need to be performed across many laboratories. Once this occurs, the data can be analyzed, and average percent recoveries and relative percent differences can be established.

Quality control is a major part of the batch processing and this data should be made readily available to clients. Full analytical reports should include the results of any quality control that was analyzed, along with the acceptable ranges of recovery, and relative percent differences between results. This will allow the client to have an additional sense of comfort in knowing that the results they have been given are reproducible, reliable, and defensible. Per ISO/IEC standards, any quality control results that fall outside of the acceptance criteria should be qualified as such and the client should be notified of the issue. These results can be included in a case narrative at the beginning of the report. By addressing the issues up front, the client is able to determine if they trust the results obtained by the laboratory or if they would like the sample to be reprocessed.

Transparency in the laboratory is crucial to legitimizing this industry. Laboratories need to be willing to communicate openly with their clients about issues that may arise and should not attempt to hide any results that are unfavorable. In the past, there have been several cases of laboratories falsifying data by either reporting out inflated potency results or inaccurately passing samples that contain dangerous contaminants. Requiring quality control with each laboratory batch, however, can help eliminate some of these issues. If laboratories are required to show evidence that they were able to spike a client sample with a known concentration of cannabinoids and recover the proper values, then there is supporting evidence to show that the laboratory is properly analyzing the sample for its true potency.

Most of the quality control that should be included with a full analytical report is difficult for the layman to comprehend and may require extensive explanation. For this reason, it is also important that analytical laboratories create user friendly certificates of analysis that allow all individuals to understand the results being portrayed. If a laboratory is performing quality control it is helpful to include a notation about this on the certificate of analysis for consumers, but there is no need to include this information. However, if anyone requests proof of quality control, the laboratory should be able to immediately produce the data.


Cannabis is currently undergoing a normalizing process. Regardless of its current status as a schedule 1 substance and decades of misinformation, public support and cultural acceptance continue to increase significantly. One of the main reasons for this positive shift is that claims such as cannabis being a more effective medicine, or a safer recreational drug, are now supported by a sufficient amount of scientific data. However, to further increase social acceptance and rebut negative stigmas, more data will be required, and the quality of that data will have a significant impact on what turn the industry takes next. Processes that confirm products are consistent with the specifications included on the package labels need to be implemented. Several cannabis producers are simply including the laboratory results without scrutinizing the data. It should be the responsibility of the laboratory and the cannabis producer, in conjunction, to ensure that the data is accurate before taking a product to market. To truly legitimize an industry that many have referred to as the “Wild West,” steps must be taken from the beginning to ensure that every product sold is in fact safe for consumption. This begins with the laboratory, as they are the entity responsible for ensuring that the analytical data is reliable, defensible, and reproducible, which can be accomplished through a strict quality control program.


  1. The NELAC Institute, 2016, Environmental Laboratory Sector, Volume 1: Management and Technical Requirements for Laboratories Performing Environmental Analysis.
  2. International Standard, 2017, ISO/IEC 17025: General Requirements for the Competence of Testing and Calibration Laboratories.
  3. Florida Department of Health, March 2018, Draft Rule 64-4.0xx - “Standards for Marijuana Testing Laboratories.”
  4. Florida Department of Health, March 2018, Draft Rule 64-4.016 - “Marijuana Testing Laboratories.”
  5. U.S. Environmental Protection Agency, 1996c, Method 8260B-Volatile organic compounds by gas chromatography/mass spectrometry (GC/MS).

Jini L. Curry is the Laboratory Director at Modern Canna in Lakeland, Florida. Christian Beauchemin is the Lead Analyst at Modern Canna. George Fernandez is the CEO of Modern Canna. Direct correspondence to:

How to Cite This Article 

J.L. Curry, C. Beauchemin, and G. Fernandez, Cannabis Science and Technology2(5), 52-55 (2019).