Flame Ionization vs. Mass Spec
Below is an example of a chromatogram for a cannabis product. On the right, we see the chromatogram using Flame Ionization. Notice the amount of “interference” at the base of the diagram. This can cause false positives and call into question the validity of the result. Through the use of Mass Spec, we can filter out this unwanted “noise” and have positive confirmation of the analytes.
Once we’ve selected the correct instrumentation, filtered out the unwanted chromatographic interference through mass selection, and confirmed identification of the terpenes, the real challenge begins – quantifying each terpene. What does that mean and how is that accomplished?
Fundamentals of Quantitation
To properly quantitate an unknown compound, first a linearity curve using a known standard concentrations is generated for that individual compound. Once that linearity curve has been prepared, the compound in the unknown is measured against the standard linearity curve to determine the concentration of the unknown compound.
Each terpene compound has a unique signal response using GC/MS. Therefore, to properly quantitate terpenes in a sample, 6-point linearity curves are generated for each terpene and spiked into a comparable matrix. Multiply that by each of the 23 terpenes your looking at 138 data points of standards – every day of analysis!
Aside from the sheer volume of analysis, the 6-point linearity curve described above performs well when prepared as standards, also expressed as “neat” standards. In other words, when the terpene standards are prepared at different concentrations in a solvent such as methanol, a predictive linearity graph is easily accomplished. However, when spiking those same terpenes into a complex matrix such as cannabis, drastic changes occur.
Significant differences are observed in both the GC and the MS when analyzing neat standards versus matrices with exceptionally high background noise, such as cannabis. Not only is chromatographic interference insurmountable if using FID, but the chemical properties inherent in cannabis trigger a complete overhaul of method parameters when transferring from neat standards analysis to cannabis analysis.
Achieving the correct analytical result is not a trivial task. Critical factors include equipment selection, instrument method parameters, and method extraction optimization. Guidance from the FDA-regulated Pharmaceutical Industry’s cGMP framework provides a clear path to make scientifically justified method validation decisions that will stand up to legal scrutiny.
To that end, we’ve accomplished the most comprehensive and robust Terpene method validation in the industry, resulting in the first truly quantitative Terpene analysis. We’ve changed the game on Terpene analysis. For the first time, you have a resource to arrive at the correct Terpene value and have scientific legitimacy to support it.
To learn about more about our Terpene Profile testing service, click here:
Tour our Laboratory
We invite you to come to our lab, meet our team, and to learn how we provide the most accurate lab results in marijuana testing. Give us a call at (720) 460-3489 to schedule a tour.