By David Isenga, Director of Science, and Jake Idoni, Director of Research and Development
A common and frustrating scenario across the cannabis industry: your internal R&D test shows a product passing comfortably, only for compliance testing to return a different result. Whether it’s potency, terpenes, or microbiology, these discrepancies can feel unpredictable, confusing, and at times, costly.
In reality, these discrepancies aren’t random. At ACT LAB, we see consistent and explainable patterns behind these differences. The root cause is often sampling variability, driven by four core factors: heterogeneity, time/degradation, volatility, and spot contamination.
Understanding these variables is essential, not only for interpreting your data, but for aligning R&D expectations with compliance outcomes and ultimately making better operational decisions.
R&D vs. Compliance Sampling: A Fundamental Difference
At the heart of many discrepancies is a simple but critical distinction: how samples are collected.
R&D sampling is typically informal. It’s often driven by speed, convenience, or visual judgment. A cultivator might select a “representative-looking” bud, or a technician may pull material from the top of a container. While this approach can be useful for quick insights, it rarely captures the full variability of a batch.
Compliance sampling, by contrast, is designed to be randomized, statistically representative, and standardized. It intentionally pulls from multiple locations within a batch to reflect its true composition. This approach is not about convenience; it’s about accuracy and defensibility.
This difference alone explains a significant portion of result divergence. But to fully understand why numbers don’t match, we need to examine the four core drivers of variability.
The Four Drivers of Variability
Heterogeneity: The Illusion of Uniformity
Cannabis products are rarely as uniform as they appear. Even within a single batch, analyte distribution can vary significantly.
- In whole flower, cannabinoid content varies from bud to bud based on light exposure, canopy position, and plant maturity. A hand-selected R&D sample, no matter how experienced a selector, will almost never reflect batch-wide potency.
- In ground flower, heterogeneity improves but introduces new challenges. Kief, which contains a high concentration of cannabinoids, settles over time. As a result, a sample taken from the top of a container days or weeks later may test significantly lower than an earlier R&D sample.
- Pre-roll production presents another challenge. During manufacturing, kief can migrate through processing equipment, meaning early units in a run may test higher than those produced later. Without proper mixing controls, this creates variability within the same lot.
- Even concentrates like distillate are not immune. Without thorough mixing, temperature control, and proper handling, stratification can occur—leading to differences between top and bottom portions of a container. If your concentrate batch isn’t perfectly mixed, your sample isn’t perfectly representative.
Time & Degradation: The Clock Is Always Ticking
Cannabis is not a static product. From the moment it is harvested or manufactured, chemical and biological changes begin.
Through processes of oxidation, cannabinoids degrade over time. For example, atmospheric oxygen will oxidize d9-THC to both CBN and d8-THC, as well as to other intermediates. This process is influenced by factors like heat, light, and oxygen exposure. Even under ideal storage conditions, some level of degradation is inevitable.
Microbial populations grow, especially under warm or humid conditions, potentially pushing a previously compliant product over regulatory limits.
Edibles and infused products present additional complexity. Depending on formulation and packaging, potency loss can occur within weeks. Emulsions may break, and active ingredients can degrade or bind unevenly within the matrix.
When an R&D sample is tested immediately and a compliance sample is tested weeks or months later, differences should be expected. These changes are not an abnormality; they are a function of time. Time between sampling events introduces measurable, predictable change. The longer the gap, the greater the potential divergence.
Volatility: What You Lose Along the Way
Terpenes are among the most temperature sensitive compounds in cannabis and can be the most misunderstood when it comes to variability. Monoterpenes like limonene and myrcene are highly volatile. They begin evaporating as soon as the product is exposed to air. Every step: grinding, transferring, and packaging can result in terpene loss.
Heat, agitation, and repeated handling accelerate this process. A sample that is handled repeatedly or stored in suboptimal conditions can show significantly reduced terpene content compared to its original state. Even transport conditions matter. A sample left in a warm vehicle may lose measurable terpene content before it even reaches the lab.
The more a sample is handled, the more results may change, especially for volatile compounds. For example, heat is often required to sufficiently blend cannabis distillates when terpenes are re-introduced. This is why terpene results are often the hardest to reproduce, even between two samples taken on the same day.
Spot Contamination: The Hidden Variable
Unlike potency or terpene distribution, contamination is rarely uniform. Instead, it often exists in localized “hotspots.”
A single moldy bud in a batch of otherwise clean flower can trigger a failed microbial test. Similarly, a contaminated ingredient in an edible production run may only affect a portion of the final batch.
This variability applies across multiple categories: microbiology, mycotoxins, pesticides, heavy metals, and foreign matter. Whether a test detects contamination often comes down to whether the sampled portion contains the affected material.
This is why a clean R&D result does not guarantee a clean compliance result, and why the reverse can also occur. Absence of evidence in one sample is not evidence of absence in the batch.
Understanding Variability Across Product Types
ACT LAB’s internal data, summarized in the Sampling Variability Matrix above, shows that these four factors, heterogeneity, time/degradation, volatility, and spot contamination impact different assays and matrices in predictable ways:
- Potency is heavily affected by heterogeneity and time across nearly all matrices.
- Terpenes are consistently affected by heterogeneity, volatility, and time, regardless of product form.
- Microbiology and contaminants are primarily driven by spot contamination and time
For example, whole flower is highly susceptible to all four variables, making it one of the most challenging matrices to sample consistently. In contrast, homogenized infusion ingredients tend to be more stable, though still subject to degradation over time.
Why Compliance Testing Often “Finds More”
It’s a common perception that compliance testing is harsher or more prone to failure. In reality, it’s simply more comprehensive by design.
Randomized sampling increases the likelihood of capturing variability and identifying hotspots. Larger sample sizes provide a more accurate representation of the full batch. Strict chain-of-custody protocols and controlled environments minimize external influences.
In other words, compliance testing doesn’t create discrepancies, it reveals the variability that already exists.
Practical Takeaways for Operators
To better align R&D results with compliance outcomes, operators can take several practical steps:
- Request ACT LAB selection specialists collect R&D samples when those results are being used to plan for compliance outcomes
- Ask for sampling training from ACT LAB’s trained team of selection specialists to ensure consistent, defensible results
- Use composite sampling by pulling from multiple locations within a batch rather than a single point
- Mix thoroughly before sampling, especially for ground flower and concentrates
- Minimize time between R&D and compliance testing
- Control storage conditions, including temperature, humidity, and light exposure
- Limit handling and agitation, particularly for terpene-sensitive products
- Build variability into your specifications rather than assuming uniformity
These practices won’t eliminate variability, but they will make it more predictable and manageable.
Better Sampling = Better Decisions
Discrepancies between R&D and compliance results aren’t random, they are explainable, predictable, and manageable. By understanding the roles of heterogeneity, time, volatility, and spot contamination, operators can make more informed decisions and set more realistic expectations.
At ACT LAB, our goal is not just to test cannabis products, but to help the industry better understand them. Because in the end, accurate data starts with a representative sample.
To take the next step in improving your testing outcomes, consider partnering with the experts at ACT LAB. Whether you need support designing a more representative R&D sampling process or guidance on aligning your internal testing with compliance requirements, our team is here to help. Reach out today to connect with our technical specialists to start turning variability into a competitive advantage.
