Cannabinoid Calibration Curves: Can I Mix These Mixes?

After the successful release of two of our newest cannabinoid Certified Reference Materials (CRM), Cannabinoids Neutrals 9 Standard, Cat #34132 and Cannabinoids Acids 7 Standard, Cat #34144, we felt it was time to revisit the question of, “Should these CRM mixes be mixed and how long is the solution stable for?” with some additional data and discussion.

First, I wanted to address why this can be a difficult question to answer for a provider of CRMs. We are often asked about the stability of our CRMs after the sealed ampule is opened in addition to questions about mixing different CRMs. This unique set of standards for potency testing is no exception, many have asked for guidance on open ampule stability and mixing. It’s important to know, while every CRM produced at Restek meets the strict criteria defined under ISO 17034 and ISO/IEC 17025, once the ampule is opened, the integrity of the standard is subject to handling and storage conditions, and it cannot be guaranteed. In other words, once that ampule is cracked open, the lab must make independent decisions about how to use, handle, and store the transferred solutions. While we have suggestions about how the lab might go about these steps considering good laboratory practices, we cannot make any guarantees about integrity and encourage labs to do develop their own testing and SOPs around CRM handling, mixing, and storage.

Sometimes we make up mixes that are meant to be combined to help address needs for specific analyses. In this case, one of the central benefits the lab gains from using the cannabinoids neutrals and acids mixtures are the high concentrations achievable when the mixes are combined. With the popularity of concentrates and other high concentration samples, having a higher concentration point as part of your calibration curve is very convenient. In addition, the ability to easily create this 16-component mixture from 2 ampules instead of a combination of smaller mixes or single components is also much simpler and saves time. Since this is how we envisioned the product would be used in the lab we decided to run our own in-house study in our Applications lab to understand the stability of these mixtures when combined for instrument calibration.

The poster that we produced from this work which outlines the experimental design, sample preparation, analytical method, and results can be found here – Measuring Stability of Combined Neutral and Acid Cannabinoids for Instrument Calibration. You can also find the rest of our posters from CSC West here. 

To summarize the findings, during the study, we found vials of mixed CRMs at 50 ppm (acids & neutrals combined) at the experimental conditions all behaved like each other except for room temperature storage at 30 days. Under the results section, we hold ourselves to a strict +/-5% criteria to show a passing criterion within this window. All % responses compared to normalized “day 0” response numbers are provided to show exactly the % variation at each data point. We hope that these findings for this question and the overall experimental design help chemists quickly design and perform their own in-house testing to develop best practices that meet their individual labs’ needs.

What CRMs would you like to see combined next in an open ampule stability study?