In one of the Sri vids they used methyl sterate as an internal standardization during calibration to account t for not so exact injection accuracy. Am I correct in this comprehension of watching the Sri videos?
yep. an internal standard would help with that.
when I got my machine, the recommended internal standard was hexadecane (C16), I stopped using it eventually because my tuned cannabinoid protocols had it burried in the solvent peak where it was no use to me.
their calibration âcurveâ protocol was also a single injection.
making a 5 or 6 point curve, with 3 injections a piece makes for much more robust quantification.
5 Likes
Respectfully there is another viewpoint regarding such expertise as a viable resource.
There are mixed blessings with bringing on board such a person. The first of course is expense. We all gotta eat and those guys generally have high expenses too so must charge reasonably to cover their services.
The other problem I have witnessed over the years has more to do with compatibility. Ego would be a synonym. What my experience has shown from a few decades of R&D work both in industries and lone wolf like now is that I have discovered that consultants brought into a project with such credentials are rarely open to new ideas and moreso I have witnessed countless circumstances where the consultant very quickly begins ridiculing that which is not a text book answer despite the efficacy of the solution or apparent success of the technique.
At my last R&D position we ultimately stopped hiring in such folks to assist me because once they learned that a high school graduate that graduated with a D- average was in charge of R&D⌠lol the situation always devolved. Inevitably any consultant hired in to help would default to giving us answers that they thought were important for us to understand rather than answer the questions or do the job that they were asked about or asked to do. One even went so far as to start suggesting reading materials for me and I was his supervisor who just wanted to see some code produced that worked!
This was during a period of time that deterministic real time operating system programming was incorporated into my designs and irregardless of my scholastic background I had become an expert inside our small industry about just how to incorporate this into a machine tool line employing multiple axis of coordinated motion control. The style of programming will blow your mind and it IS NOT anything like traditional linear programming at all. All code was ANSI C yet despite hundreds of thousands of lines of code if counting libraries not one line had function main(); Yep, an entire machine tool robotic solution written in C in which function main(); is ommitted. Why? in essence it is because all functions present are executed simultaneously upon power up as if each function was an independent computer system and communication between functions is ONLY possible via semaphore. This means that done correctly each function acts as a Finite State Machine which must perform independently but coordinate by semaphore. This got the college folks we tried to get crossed up horribly because to them it was entirely new and demanded some real mental gymnastics to pull off a machine control solution with so many axis of motion and all of which must be coordinated. This is much harder than it might seem. One of the guys the University sent us quit the same day lolz.
So cost and compatibility can be a real issue. Higher ed and licensed types tended to be inflexible in thinking but a repository of facts and factoids while the high school senior we ultimately hired in and was a brilliant student and took immediately to accepting guidance and correction and had a real eagerness to learn excelled impressively. The kid picked up deterministic programming like it was second nature. The downside was he graduated school and left! @cyclopath has an impressive acedemic background though I think not as a chemist per se but without hesitation I would hire that guy into a position dealing with analytical testing because he is approachable and a very quick study. Plus he has great fashion sense.
6 Likes
For the record, I was asked not to return for my last year of high schoolâŚwhich seemed like a reasonable arrangement at the time.
I believe it had something to do with me sharing knowledge. probably sharing how to defeat the locks on the chem storeroom doors 
6 Likes
would a 10 port sample valve be a worthy upgrade for Cannabis testing, what do they do? i am very green in terms of GC terminology and how to operate one but the more i research the more i want one! that cheap 8610c above come with a TCD detector and 10 port gas sampling valve setup. a person could sell the TCD on ebay to help fund the purchase of an FID and proper columns for cannabis testing. a real treat would be 3 FIDâs with the appropriate columns for cannabinoid, terpene and residual solvent testing.
Can anyone link a crash course video for a beginner on using one of these Sri gcâs? Iâve been watching tons of Sri videos but I feel like Iâm missing the main educational chunk of knowledge in operating a GC in general. I guess youre basically injecting a measured amount of feedstock into the port where it heats up in the oven and the capillary tube (column) and hits the detector where an element or flame is present. The petrochemical then releases ions which get picked up in the detector and the âtimingâ of the compound breakdown into ions is the various peaks shown in the software. Is this understand in correct? The FID detector is a type of detector utizing hydrogen for fuel to provide a flame. This particular detector is best suited for cannabis testing. An autosampler is a mechanical and electronic device that does the injection for you allowing for more precise control and better accuracy for quantifying the results?
1 Like
Im in the exact same boat as you. Ive literally wanted one of these for the past 4-5 years. As soon as shitty oil started making around my way, i wanted to call out these phonies.
Now that im getting into distillate and higher potencies, and getting around you all with similar desiresâŚIts really rekindled my want for a testing machine. This seems to be a deceit deal turn key. Im sure they would take less with a best offer. $5-6K for a way to test seems super reasonable considering what some of us having into extractors and lab ware.
2 Likes
these should get you on the right track!
8 Likes
You wonât be able to test for pesticides with this machine. Just potency,resdiual solvent, and terpenes. If you want more you need lc/ms with a dad dector and a qqq dectetor.
thanks for those buddy! ive already watched all of those maybe twice now ha! just trying to see if i can find some more videos on basics or high level introduction to GCâs in general.
2 Likes
This is a good one too.
1 Like
Great synopsis with a relevant anecdote. In graduate school we tend to get over specialized. We have an entire analytical staff who run our tests.
I worked at a small company where my division had 2 scientists, me and my boss, the rest had no degree or unrelated degrees. We couldnât afford to run our division any other way. In cannabis thereâs more engineering and practical know how. Iâm glad to be a part of this forum to help me get to speed. If I can help at all with interpretation and explaining how organic chemists go about solving a problem, Iâm glad to help.
4 Likes
Just another task where âit puts the cannabis in the tube!â is an apt description 
One way Iâve described my GC to patients is as a long decorated tube. Imagine folks walk in at one end, and out at the other. Depending on the decorations, some of the folks will take longer to make it through, as they stop to examine them. Others will wander right through. Turns out itâs repeatable. George always makes it out in 5min. Henry takes 8min. Lucy takes twelve. Swap the decorations, theyâll come out in a different order.
Swap âdecorationsâ for âspecial coatingâ & âfolksâ for âmoleculesâ and youâve got a decent handle.
As far as the flame ionization detector, it can also be looked at as a carbon counter.
Itâs a ~1000C hydrogen flame. And it essentially counts electron flux through the (C-H2)n => CO2 etc occurring in that flame
I think there is a better discription of exactly whatâs going on somewhere around here. Maybe Iâll go find it before someone objects too vehemently to the above simplification
3 Likes
I plan to go to 2 columns, 2 FIDs for terpenes and potency. The residual solvents and terpenes can be done on the same column with a Perkin Elmer protocol. They developed this internally and presented it at a conference in Oakland.
If anyone can them to share the specifics without spending 50k on their instrument, please do. When I have time, I work on it myself. They gave away a big secret by showing that the solvent in which they dissolve the oil is slightly higher boiling than the residual solvents we check for. It is still volatile enough for GC. Let the guessing begin!
1 Like
Heptane?
1 Like
I saw one of the SRI vids where they âHugheâ mentioned using 1 FID and column for cannabinoid potency + Terpene and another for residual solvents.
watching this one now⌠Gas Chromatography | working principle and instrumentation lecture - YouTube
im just gonna have to watch them all i think: https://www.youtube.com/channel/UCQHQDR6_nsDKDUboEaW1R6g/videos
@Beaker i would love to see you dive into a GC unit to analyze your experiments youâre always doing. Plus you can be the guinea pig and hold us basement lab folks hands so we can follow your footsteps! Ha
1 Like
Sure, pick the nerdy kid to go firstâŚ
4 Likes
I found my notes on this method. It was presented by Tom Kwoka from Perkin-Elmer. They use HS -GC-MS for full vaporization (HS = headspace). However, to my original postâŚthey developed a HS-GC-FID method that uses an extraction solvent that elutes after the 7.2 minute long residual solvent run and the 8.1 minute terpene run. So a 20 minute run when all is said and done. The residuals are done in 7.2 minutes with the highest peak analyzed being xylenes. After that, in the same injection, they resolve the standard 37 terpenes that everyone is used to seeing in from your testing lab. They mention an extracting solvent, NOT a carrier solvent. My dumbass organic chemist sometimes brain doesnât think past âit shoots the worked up rxn mixture in the tube, it looks for reaction completionâ when using GC.
ASIDE
Iâve been using it on and off for 20 years, but never had to service it or care about method development. But Iâm pretty good at interpreting the results especially when I test the pure compounds that I make.
END ASIDE
So the mystery solvent still exists, but itâs an extraction solvent that boils higher than xylenes. They said theyâd post their slides later but this talk mysteriously wasnât posted. If anyone has a headspace unit and is curious, message me and I can try to get it out of them at the next conference I go to. And if I do, you owe me $50k for the GC and service plan theyâll probably make me buy.
As for modelâs: Agilent 5890âs and 6890âs were used by almost all the companies (materials and pharmaceuticals) that I worked for and contracted for back in the day. I couldnât have even told you another brand unless I guessed by knowing the other HPLC manufacturers.
1 Like