Accurate Terpene Analysis

How to accurately determine the amount of terpenes in cannabis products

Accurate identification and quantification of terpenes in cannabis has proven to be an extremely challenging analysis. This is achieved by: (1) correctly identifying the terpene that us

of interest, and (2) by accurately determining the quantity. Both parameters feed into each other, and both are necessary to create the correct terpene “fingerprint”. Here’s how we control each of these parameters.

Identification

Proper instrumentation is paramount for accurate quantification of cannabis terpenes. The most common way is to use a gas chromatograph with flame ionization detection (GC / FID).

Analysis of simple matrices; e.g. Pharmaceuticals work well using GC/FID due to low background interference, but this changes when applied to cannabis.

There are hundreds of phytochemicals in the cannabis plant and this natural matrix presents a chromatographic challenge when using GC / FID.

Flame ionization detects almost everything in the sample – not to be confused with identifying everything in the sample.

To solve this problem, GC with tandem mass spectrometry (GC/MS) is an excellent tool for this analysis. GC/MS allows us to filter out unwanted “noise” from our analysis, thereby precisely identifying the terpenes of interest and creating an accurate fingerprint. Testing the terpene content by GC / MS allows us to obtain three levels of confirmation: (1) chromatographic retention time, (2) molecular parent mass, and (3) daughter / fragment ion mass. This eliminates the possibility of false identification of each analyzed terpene.

Mass Spec (GC/MS) vs Flame Ionization (GC/FID)

Once the correct instrumentation is selected, unwanted chromatographic interferences are filtered out by mass selection, and terpene identification is confirmed, the real challenge begins – quantifying each terpene. What does this mean and how is it achieved?

Quantitation

Once the correct instrumentation is selected, unwanted chromatographic interferences are filtered out by mass selection, and terpene identification is confirmed, the real challenge begins – quantifying each terpene. What does this mean and how is it achieved?

Basics of quantitation

To properly quantify an unknown compound, a linear curve is first generated using known standard concentrations for that individual compound. Once this linear curve is prepared, the compound in the unknown is measured using a standard linearity curve to determine the concentration of the unknown compound.

Quantification of terpenes

Each terpene compound has a unique signal response using GC/MS. Therefore, to properly quantify the terpenes in a sample, 6-point linear curves are generated for each terpene and added to a comparison matrix. Multiply that by each of the 22 terpenes if you’re looking at 132 standards data points – every day of analysis!

Recovery of terpenes

Beyond the scope of the analysis itself, the 6-point linearity curve described above works well when prepared as standards, also expressed as “pure” standards. In other words, when terpene standards are prepared at different concentrations in a solvent such as methanol, a predictive linear graph can easily be obtained. But when these same terpenes are added to a complex matrix like cannabis, drastic changes occur.

When analyzing pure standards compared to matrices with extremely high background noise such as hemp, we see significant differences in both GC and MS. Chromatographic interference is not only insurmountable when using FID, but the chemical properties of cannabis trigger a complete overhaul of method parameters when moving from pure standard analysis to cannabis analysis.

Summary

Achieving the correct analytical result is not an insignificant task. Critical factors include equipment selection, instrument method parameters, and method extraction optimization. Guidelines from the pharmaceutical industry’s cGMP framework, regulated by the FDA, provide a clear path to science-based method validation decisions that will be supported by regulatory oversight.

To that end, we conducted the industry’s most comprehensive and robust Terpene Method Validation, resulting in the first truly quantitative Terpene analysis. We have changed the game on Terpene analysis. For the first time, you have a source to get your Terpene value right and have the scientific legitimacy to back it up.

To learn more about our Terpene Profile Testing Service, click here.