Chromatography Forum

I'm looking for a method that can be used for terpene analysis on a GC-FID that does not require headspace sampling. I have multiple samples to process that would make manual headspace sample injections tedious. I'd like be able to use the auto sampler that I currently have for the analysis.

Why not just extract and inject as a liquid ?

Peter

Why not just extract and inject as a liquid ?
Peter

Exactly what I'd do. I'd dissolve/blend, etc., and filter if necessary. We've done terpenes before, used in some products with "orange power" solvents and Fels Naphtha.

What's the matrix?

Injecting as a liquid is what I'd like to do. I just haven't seen any references on injecting as a liquid rather than as a gas. The matrix is cannabis, and also hops.

Have you looked at the Quecher's technique?

http://www.chem.agilent.com/en-US/Produ ... fault.aspx

https://www.youtube.com/watch?v=RAOSR4WzKU

We are currently using the Quechers for sample clean up after performing the extraction of thc from edible products.

If the terpenes are concentrated enough, Quechers should work. If you're looking at low concentrations of terpenes, it may fail. Headspace analysis for those things is difficult to beat, especially for low concentrations.

The terpenes are fairly nonpolar. They should extract into hydrocarbons solvents, ethyl acetate etc. THe trouble is if there is lipid present in you sample that will also extract. You could also steam distill. I use a clevenger trap to collect volatile oils.

Hi - Have a look at the recent Restek blogs - they have some work on terpenes related to cannabis.

http://blog.restek.com/

Page down a bit.

WK

Hi Dustin, looks like you're getting some good help on these boards, great to see.
Aidan

Hi Aidan,

Thanks for suggesting this forum. I've been finding a lot of great information on it.

Hey,

I'm doing some method development for this exact thing.

I haven't come across any published lit that deals with liquid injection, everything seems to be through headspace.

What I'm trying is to just prepare a terpene mix standard in a methanol matrix to match our extraction solvent. I have been using the restek paper as a guide and working from there. I injected the mix onto whatever 30m column we had in there and was able to get ok resolution. Gonna buy another restek to match what we use for headspace and expect to match resolution. Our GC can't get flow rates as fast as restek, so we some slight co-eluters.. I then injected straight from our extraction solution... was able to see myrcene and some others by matching retention times. so i think this could work. Have to do a lot more now!

How much progress have you made in the last month?

so im working on the same thing now.. fyi though dmso has a late retention time... very interesting for use with resid solvents of rso

going to try a Quechers with DCM maybe? meoh isnt stripping terps the way i want it to and yeah... any other ideas of solvents? our standards came in isopropanol but online scientific journal says terps most soluble in ether , chloroform and ethyl acetate. Dont want to deal w the peroxides ether forms and we dont have chloroform but we have dcm and i think it should be similar. also thinking of an organic solution with 2 or more solvents maybe like isopropanol and DCM