Sorry, HPLC autosamplers operate at room temperature.
GC autosamplers are more complicated because they need to move the liquid sample into a hot zone and this typically requires a moving syringe.
Its not really true that autosamplers improve the accuracy of the results. We get the same precision with an autosampler that we get with a practised human. The only advantage of the A/S is that its painless to run the sample multiple times and average the results.
A disadvantage of the A/S is that its more expensive to run each sample since the 2ml vial is not typically worth re-using, whereas the bigger 40ml extraction vial is easy and cheap to clean and re-use.
Since you have to extract in the bigger vial, you then have the added labor of pipetting the extract into the smaller A/S vial. This step is error prone and by the time you load the A/S tray you could have run all your samples manually.
We have found it makes more sense to measure terpenes from the same liquid extract you use to measure the cannabinoids. Headspace is difficult to calibrate and very dependent on temperature.
When you extract the cannabinoids you are also perfectly extracting the terps. Why do two sample preps when you could just do one ( the liquid extract ). With GC we can measure the terps and cannabinoids all in one single analysis. See this chromatogram from the SR?I website. http://www.srigc.com/cn/downloads/333/Terps+THC.pdf
Anyone use or know about Kratom testing? I’m looking to test the two main alkaloids (mitragynine & 7hydroxymitragynine). I just started doing research so I’m very new to this. So far I have found the link below which looks to be some kind of testing profile? I’m looking to purchase something in the next 2 weeks.
As always
Thanks guys!
Yes. I have sold many GCs for Kratom testing. I can send you more information on the mitragynine standard and example of chromatograms of actual kratom testing done on the SRI 310MM GC.
Summer
SRI
Yes. I have sold many GCs for Kratom testing. I can send you more information on the mitragynine standard and example of chromatograms of actual kratom testing done on the SRI 310MM GC.
If you did purchased one within the 13 days since you posted, let me know if there’s anything you need as well
Summer
SRI
Anyone have positive feedback on Orange at this point in the game? We don’t trust our results as the machine initially had the wrong calibration, and post update the results of homogenized samples split between the unit and a reputable lab show too large of margin.
The hardware is one thing
The operator is another. The calibration is a crucial point, in needs to be done daily. And the procedure must be repeatable.
My lab 
Currently working with a Waters Acuity UPLC H Class for potency analysis. We calibrate with 11 cannabinoid standard. The detector is a PDA.
For the terpene analysis we are running a Agilent GC-MS. The sample is obtained through head space.
You work at an extraction facility? What state?
I work for a grow facility in Florida. In our state its seed to sale so in our facility we grow, extract, distill, formulate, fill and package. I currently work in the analytical lab but I have worked extractions and production here as well.
Geez how many ppl work in the analytical lab? How many ppl in the whole place? if you dont mind me asking
2 chemists and one biologist in the lab. At this point I believe we are right around 100, maybe a few more. The facility is pretty big.
For those who use/have used derivatization agents, is there a substantial impact on resolution? If we had no interest in quantifying acidics, are you better off just shooting as-is? Is the decarb in the injector more of a crapshoot than successful derivitization?
I get good resolution on a sri310 just shooting without derivatizing.
Decarb on the heated injection port works pretty well, but there is a bit of a long shoulder. Doesn’t seem to affect precision, and who TF knows about accuracy anyway it’s such a shit show there’s basically no lab you can trust enough to verify your accuracy lol.
am just now getting mstfa working as a derivatiser. Resolution seems ok but not quite as good. Am tryin to optimize now, so should be fine after a couple days.
I’ve been using an SRI-GC without the heated injector port over a period of 5-6years. At one point I had it dialed beautifully to my local analytical lab. then the lab director stopped doing the bulk of the work, and (imo) their accuracy slipped. The peaks are definitely not as well shaped as they are on the same machine with a heated injector port, but a decent calibration curve goes a long way.
I was planning on setting up “acidic” testing on 310MM in another lab six months ago, but ran into problems with the FID ignitor that required a trip back to the factory. My time there ran out before I got to play with it.
Bumping this old thread because no-one will spoonfeed me and there’s a lot of conflicting info on the subject
So I’m looking at getting some stuff to do TLC and I have a few questions:
Is it necessary to decarb all samples?
What extraction solvents are best? I’ve seen methanol, ether, hexane, etc
What type/grade of silica/alumina plates are best?
Is fast blue B/BB the best developer? Is it necessary to use NaOH for BB prep? Spray/dip? What concentration? I’ve seen .5% and 1%, and a few other random ones that aren’t precise
I saw someone using bromocresol green to test for decarboxylation with chromatography paper on here, is that just to determine when the product is no longer an acid?
Is 80:20 hexane:diethyl ether still a good mobile eluant? Chloroform? I’m looking for opinions on this one
Is there a guide to retention factor changes by solvent/plate type?
The basic process from what I can see is:
Mix 100mg sample with 1mL methanol or hexane, allow time to extract.
Use capillary tube/micro-pipette to deposit 2-4uL sample on plate
Place in chamber with mobile eluant below the sample dots(chloroform?), allow capillary action to reach the top line of the place(opposite of the dotted samples/stationary phase which are at the bottom)
Allow plate to dry
Spray/bathe with developer(Fast blue B/BB? concentration? - bathing it is best practice, correct?)
Measure/photograph results
Newer methods all seem to be locked behind paywalls, but I see various mobile phases being used in almost everything.
Is my best bet just gonna be buying the kit linked above or a similar one, and adding materials as needed? I don’t have a great understanding of all this, and I’m hitting the wall in terms of what I can do by myself.
random resources I’ve used:
DIY Thin Layer Chromatography (TLC) of cannabinoids at home - tutorial | Rollitup (by far the best)
https://www.icmag.com/ic/showpost.php?p=7063635&postcount=18
How to make a cannabinoid analysis- Alchimia Grow Shop
Home TLC Thin layer chromatography | Page 4 | International Cannagraphic Magazine Forums (lots of dead links but some solid info)
High Performance Thin-Layer Chromatography (HPTLC) data of Cannabinoids in ten mobile phase systems - ScienceDirect
https://www.greencultured.co/cannabis-analysis-and-marijuana-testing/
Cannabis, THC, CBD, CBN, CBG Testing kits Instructional Video www thctestkits com - YouTube
In House analytics - #96 by cyclopath
High Performance Thin-Layer Chromatography (HPTLC) data of Cannabinoids in ten mobile phase systems - ScienceDirect
paywalled info I couldn’t fully access that looked useful:
Sherma, J., & Rabel, F. (2019). Thin layer chromatography in the analysis of cannabis and its components and synthetic cannabinoids. Journal of Liquid Chromatography & Related Technologies, 1–16. doi:10.1080/10826076.2019.1663529
you seem well on your way.
the rollitup write-up seems sufficient to get you where you need to be.
I’d suggest you start with a kit.it is not the least expensive way to obtain the required parts, and you’ll want to upgrade some of them (some of them sooner than others), but it will get you the basics all in one place, and will come with instructions.
it’s NOT difficult (you may be over thinking it).
to get around those paywalls, try the Sci-hub.tw link at the top of the page.
there is no need to decarb ALL your samples. but decarb is informative. In a 3rd party lab setting we ran decarbed and non-decarbed for each sample.
the fun thing about fast blue salts is that you actually get a color code in addition to retention time.
The kits don’t seem to be very clear about the contents, but I’ll check some out to try and start with.
Do you have any suggestions as far as plate type, solvents to use, or fast blue bb concentration? When the time comes it’d be nice to have an idea of what I need as far as consumables. Not knowing any better I’d like to try aluminum plates(because I can cut them to size as needed)
Unfortunately, all those details have faded into oblivion at this point.
I spent 2-3weeks in a lab doing TLC to meet OR mandated 3rd party testing back in 2013. I personally ran only a couple or ten plates, then set a friend up as the technician… I spent the majority of my time bringing two SRI GCs online (also got the incubator/petri-film/colony counting for microbial up and running).
I was looking for a collaboration, but moved on for ethical reasons…
I would expect Alu plates to be more expensive than silica on glass, and don’t see much advantage to varying the plate size between runs. We used chloroform as the mobile phase, and were using consumables and protocols from Cannatest up in WA. I believe they licensed alpha-cat to sell their kits, but you should confirm that (try calling cannatest).