THCP and 11Hydroxyd9THC chromatogram on SRI 310mm GC

This chromatogram shows where THCP and 11Hydroxyd9THC elute relative to the usual cannabinoids
They both elute considerably later than CBN.



Thanks for this! Just so I’m clear, this is on the 15mxt35 column?


would also like to know! Thanks for the work!

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The 15MXT35 .15 mic is the pre-column in this case. The analytical column is 30MXT502.2 1 micron.
The two columns were in series for this test. I would not expect much difference in retention order or relative retention times for any non-polar or mid-polar column. Having a thinner film column in series before a thicker film results in sharper peaks due to the focusing effect. In this configuration, the pre-column can also be backflushed using the pressure switching technique to catch and vent any heavier components like MCT or Olive oils so they don’t contaminate the main column.


Do you have details on how you’re achieving this on your machines (posted on your website perhaps)?

I’ve wanted the ability to back flush my columns since learning the Agilent’s could be taught that trick.


I will have a document soon. I will make sure to post it here as well on
Briefly there is a swagelok “tee” at the midpoint ( in the column oven ) where the two columns connect to each other. The columns are butted together in a sleeve which holds them in alignment. the third leg of the “tee” is normally dead ended but when a gas solenoid is activated the carrier gas is switched from suppling gas at the normal injection point ( on column injetor ) to supply gas at the mid-point. Any molecules which have exited the pre-column into the main column continue on towards the detector. Any molecules which have not exited the pre-column are stuck there temporarily since the pre-column then has no carrier flow. At the user’s discretion another gas solenoid is then activated simultaneously or at some later time when the oven temp is higher to vent the on-column injector to atmosphere through a carbon trap tube. The carbon trap insures that the backflushed molecules can’t re-enter the system. Adding the backflush hardware will raise the price of the 310mm GC by about $1500 ( currently $10810 ) to pay for the extra column and backflushing solenoids, trap etc. Our hope is that this will make it easier to measure cannabinoids in oils like MCT, coconut and Olive Oil since it eliminates the need for sample cleanup prior to injection. We hope this will also help with edibles analysis ( gummies, butters etc. ).


…and we can trigger those solenoids as (timed) events in PeakSimple?

Thank you good sir!!

Well worth the price of admission for that trick!!


Yes, exactly. We will have some kind of field upgrade so existing 310MM GC can be upgraded.


What is the approx amount of these analytes on column you think? Just need to get a ballpark on the amount or what the 1ul inject concentration was. Thanks, and thats a real nice method for throughput *tip of the hat

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Most of the peaks are about 200nanograms on column. The 11hydroxyd9THC is less but not sure exactly how much.