The resolution of their method is indeed very poor.
Even for normal CBD products, such method is not ok…
The method I employ with GC-FID lasts at least 17minutes. Main cannabinoids appear between 11 and 15 minutes, separated by at least 20 seconds from each others… and there you can see that there are even few more others next to the main ones, generally present at lower levels.
I wish i could go into it deeper, but I am not the one that made our method. I would be happy to share the chem station data with anyone that is interested though.
Analytical is not my strong suit, i know just enough to get by and i am happy to say im always within a few percent to pixis labs.
I occasionally described my method in various post in this forum.
It is adapted from a method I found in forensics literature.
In my case I employ GC FID. In short:
30 m HP-35MS capillary column
He as carrier gas
split injection
starting temp 80°C, ramp up to 180°C at 30°C/min, then up to 280°C at 10°C/min, then higher to 320°C in case of oil tinctures.
There are variable parameters than can be tuned.
The key is to have a slow enough temperature ramp in order to have a convenient separation, associated to a long enough column … but this extend the run time. A lot of commercial lab want to go fast.
I made the method to primarily look at flowers and tincture, and be able to discern most terps and cannabinoids in the same run.
It was zinc salts, I can only surmise either my CBD had some high boiling terpenes that didn’t fraction off properly, or that I didn’t rinse enough. But I also wouldn’t think that the acid would boil over but I guess probably in trace amounts
To me the ZnCl2 route looks the very similar to the acidic clay, AC, acid methods.
I don’t think the reaction is straight in any case. But it seems that the amount of intermediates (from CBD to D8, including D9 in between, plus presumably two others) varies as a function of catalyst.