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Residual Solvents in Cannabis...and Terpenes with Simon & Garfunkel

17 Nov 2014

By now, a lot of people in the industry know that headspace-gas chromatography (HS-GC) is the ideal analytical technique for analysis of residual solvents in cannabis concentrates, but wouldn’t it be nice to be able to perform another pertinent cannabis analysis on our fancy headspace instrument? It turns out that we can. The beauty of HS-GC is its ability to separate volatile analytes from difficult sample matrices with very little sample preparation. While terpenes are less volatile than residual solvents, all cannabis terpenes (with the exception of phytol) are volatile enough to analyze using HS-GC. With that in mind, we developed a preliminary method for HS-GC analysis of terpenes in cannabis.

In order to keep things as simple as possible, we developed our terpenes method on the Rxi-624Sil MS column, which is the same column that is recommended for residual solvent analysis. Luckily, Jack Cochran had already established that the column does a really good job at resolving terpenes. This means that you can run two different analyses on the same instrumental setup, getting more use out of your instrument investment – hooray! Here’s what the chromatography looks like for a comprehensive set of terpenes:

Terpene Chromatogram
The Rxi-624Sil MS nicely separates a comprehensive set of terpenes.

To test out the method sans cannabis, we decided to determine terpene profiles for some of the following common herbs: parsley, sage, rosemary, and thyme (now the title makes sense!):

Terpene profiles of common herbs using the Rxi-624Sil MS
Terpene profiles of common herbs using the Rxi-624Sil MS

As a disclaimer, this data should be considered semi-quantitative, and the method is preliminary, but our overall profiles matched up well with what we could find about terpene profiles of these herbs. We also profiled hops, which are a close cousin to cannabis.

I will be discussing this and other work at The Emerald Conference in San Francisco on January 23rd. The conference agenda includes some good speakers from the cannabis industry, and it looks like it will be a valuable conference for anyone who can attend.