GC vs HPLC for C3 plants compound analysis?

[|FCG|Frank]

Hello,

I am a graduate student in a science field only very loosely related to biochem. Within the next two years I may be opening a medical cannabis dispensary, and would prefer to have an on-site lab with which to test samples of the product I would be cultivating. I haven't touched a GC or a LC in years (last time was probably in chem 301 in my undergrad studies) and honestly have no detailed idea on how to operate them (I just understand what they do).

I would like to acquire either a GC or LC and then seek out the professional formation I would need to properly prepare samples, operate the machine and interpret the results. I'm quite confident that my current science background will be enough to give me a good enough grasp on things if I get the proper training. I am currently in the early stages of planning this operation, and was hoping I may ask you a few questions in regards to acquisition costs and other smaller operational details.

The main two compounds of interest are delta-9 THC and CBD.

1) Regardless of cost, which technology offers more precision to measure the compounds of interest between GC or HPLC?
2) I estimated that for 10,000$ I could acquire a GC with a column to automate the testing. Is this a fair estimate? I could not find conclusive numbers on a HPLC unit.
3) I would obviously need to get reference materials for the tests. What's the approx. cost attached to those?
4) Obviously sample preparation will have to be done manually, but is there a way to automate the sampling input, testing, and results output?

I am in Canada if this changes anything in regards to costs.

Thank you very much for your help in advance.

[bisnettrj2]

Interesting. Restek seems to have been doing a lot of research on medical marijuana, and they have quite a few resources on their website for medical marijuana testing. Depending on how far you want to take your medical marijuana analysis, you may also want to think about pesticide and herbicide residue testing, unless you'll be growing your own and are planning to not use pesticides or herbicides.

http://www.restek.com/sitesearch/site?S ... ton=Search
http://www.restek.com/Reference-Standar ... -Marijuana
http://www.restek.com/Landing-Pages/Medical-Marijuana
http://blog.restek.com/?p=4793
http://www.restek.com/pdfs/GNAD1232-INT.pdf
http://blog.restek.com/?p=3018

As for cost, you can get an HPLC-UV system for anywhere from $2500 to $100k. Go to LabX.com, or look for third-party instrument vendors who sell refurbished systems. As for GCs, the same price points will apply, but I would opt for one with an EPC (electronic pressure control) over an instrument with manual gas flow adjustments, and one with an autoinjector (autosampler). For an HPLC, I would want an autosampler and at least a binary pumping system capable of doing gradient analysis, along with a thermostatted column compartment. Without having used either GC or HPLC in some time, I would opt for a "warrantied" system, or maybe one with an annual preventative maintenance service visit built into the price, and perhaps a familiarization visit included. If you go with an HPLC, Tom Jupille of LC Resources (and this Forum) offers many training courses that would definitely be helpful to you:

http://www.lcresources.com/training/trsched.html

Cost of ownership on a GC versus an LC is questionable. Columns are similarly priced, but GC columns can be cut shorter and shorter while an LC column cannot. GCs have inlet maintenance supplies that are usually replaced much more frequently than on an HPLC. I have no idea what high purity gas costs, but a case of HPLC grade methanol can cost $250-$500 US for 16 liters, and acetonitrile can go for $500-$1000 for the same amount. HPLCs will generate solvent waste that needs to be properly disposed of, while a GC will (generally) not. In my opinion, HPLCs are definitely more for the mechanically apt, and if that isn't you, I would stick with GC. I think accuracy of either technique should be similar, and with a well-maintained instrument and a well-developed analytical method, the precision will depend more on the operator than the instrument.

but is there a way to automate the sampling input, testing, and results output?

For the sampling, there is probably a lot you would need to do to get a sample ready for processing, so this may be an exceptionally manual process. The instruments, however, once loaded with sample extracts and reference standards, should be able to run autonomously via the instrument control software. Once the data from the analysis has been acquired, the processing of the data can be accomplished with one of several different data processing platforms. A nice little chromatography acquisition and analysis software platform I've used is called ChromPerfect by Justice Innovations.

http://www.chromperfect.com/index.htm

You've probably already considered this, but you'll also need the generic suite of lab supplies, like computers, printers, gloves, lab coats, fume hoods, organic solvents, refrigerators, freezers, glassware, pipettes, balances, micro syringes, solvent cabinets, solvent waste drums, vials, vial caps, etc. VWR has a new lab setup program that may or may not be useful to you:

https://us.vwr.com/store/content/extern ... d_save.jsp
https://us.vwr.com/us.vwr.com/en_US/ima ... graphy.pdf

Hope this helps. I would probably shoot for $100k US just to get a small lab up and running, because the instrument for the analysis is just a small part of what you'll need to do quality work.