Small Gas Chromatography unit SRI?

[drPaul]

I’ll bet $5 that their extraction solvent for residuals is one of two: octanol or DMSO. Any takers?

Aside from that, I’ve had extensive experience with the SRI machines, and for the applications being discussed here they are probably adequate. SRI builds a lot of their components, including injectors and detectors, out of Swagelok parts like Tees and Crosses, so they are cheap to build, and rugged. That said, there are some limitations: the injector design pretty much limits you to “on column” injection, which is to say that the sampling syringe is guided into a wide-bore column, where sample is directly deposited.

Not a bad technique, but it limits you to those column diameters (0.57 mm ID), otherwise the injection needle won’t fit. These ‘megabore’ columns were originally designed for separation of highly volatile compounds like solvents. Cannabinoids are another class, with both lower volatility, and the complication of numerous compounds of highly similar structure and close chromatographic spacing. Some isomers of d9-THC, like d8, d10, etc. may be indistinguishable from one another on these columns, and with the proliferation of spd distillate out there, a botched, high ‘mystery isomer’ rich sample could look like high THC with analysis on this setup, only to test low in a certified lab with higher resolution instruments.

To get the most out of any GC system internal standards are a must. I use benzophenone, which is a solid (easy to measure accurately), and it elutes (emerged at the detector) between the sesquiterpenes and the cannabinoids. The use of IS compounds will dampen irregularities in injection volumes & operator technique.

One last thing: those 10-port valves on a lot of these machines were put on to facilitate gas sampling or “purge and trap” analysis of volatile compounds, usually in water samples. A lot of these setups were sold for remediation monitoring…think gasoline in groundwater! You might be able to take advantage of these for residual solvent analysis, but it would take some work. Not for the faint of heart!

For my dollar, I’d rather spring for a used HP 5890 or 6890, and have the flexibility of many more injector, column and detector options…heck, there are even mass specs that can be added on. Check eBay!

[cyclopath]

Thanks @drPaul!
Was just about to try getting you involved in this one

[ProfMeow]

I’ve used two of these machines. I’ve used the 8610C and the one with the hydrogen generator. They are alright. The software isn’t the greatest.

Someone brought up concerns about being able to easily replace the columns. I can confirm that it is extremely easy to change columns on these.

They aren’t extremely accurate machines but you’ll get some good use out of them. The customer support offered by SRI makes these worth getting if you have no analytical chemistry experience. They will hold your hand and walk you through everything over the phone anytime you need them too.

I think they oversimplify things sometimes though. I don’t like their methods for edible testing because they literally just tell you to put the edible in extraction solvent and water, filter, then shoot it. This method will ruin your injection syringes and column and screw up results until you replace everything. If you intend to use these for edibles, you’ll need a few more things to do it right.

I give these machines 8/10 overall. The “gasless” model is really cool and convenient, tech support is great, methods provided are subpar.

But with no analytics experience these are probably the best direction to go in, due to the massive amount of free help the company will offer you. Just take all results as a close approximation and not a definitive result.

[square_root_pharms]

I found on their website they have detectors for pesticides without need Ms?

https://www.google.com/url?sa=t&source=web&rct=j&url=https://srigc.com/cn/downloads/88/MedicalCannabisPesticideTestingApril2011.pdf&ved=2ahUKEwjv4uTZh7LeAhWJT98KHSpeAdcQFjAAegQIAxAB&usg=AOvVaw0iTkKfDg2I2WEAWultcDW3&cshid=1541036520554

[cyclopath]

Some Pesticides. Useful if you know what to expect, or can see what you need to remove.

[doc_simple]

i have an 8610c with a fancy h2 genefrator I refurbed for under $2k including standards and column.

I have spoken with the gentlemen at SRI at length (and they really are great helpful guys, even when its a used machine).

They recommend the internal standard method which should remove some of the variability. But… I’m old school and had to build my own calibration curve. It was a great learning experience and I was able to get +/- of 10% but when testing new material I noticed massive drifts. Finally realized the scale I was using was good to +/- of 1-5 mg. Seriously no bueno.

One lucky auction later I have a mettler toledo with tolerance down to 0.001 mg. Amazing price. Showed up with no weigh plate though so know I’m waitng on $400 in chrome plated vanadium wire to put it to work.

If I were a betting man, and of course I am I work in cannabis, i would say that with the scale and a rebuilt cali curve I will easily get my +/- down to 5%. The key is that no one but me touches certain pieces of equipment in the lab but me. That elimates user to user variation.

Finally I would in no way consider using 2 columns. In fact if anyone wants the terpene column for the 8610c I will sell it for $175. I have 2. Don’t ask.

The reason for this is that the instrument will need a new calibration every time you swap the colmns and its not neessary. If you run it slow and low you can get terpene peaks as well. Restek sells 2 terpene standards as well.

hope this wasnt alll covered before but best of luck.

[square_root_pharms]

Can’t you run two columns using a split ferule did not need to change anything or recalibrate

[square_root_pharms]

where did you score your unit and parts?

[doc_simple]

Some of the units will have two injection ports which you can setup to run both. Its not a split ferrule, actually that would just be a broken ferrule

As someone earlier noted be sure it has the FID. I bought a unit for $600 that does not have the FID and now sits in the closet.

I founf the FID unit for $1500 on ebay, offered 1K and they took it. I then bought the new column ($500) and 2 of the terpene columns because I found a good deal. Finally I found an absolutely gorgeous H2 generator that turned on but they were selling for parts, scored that for $200. Once I got everything assembled I turned everything on and… the H2 generator only generated a dribble.

Out comes the screwdriver. The lines in side were pretty disgusting so I replaced all the internal tubing turned everything onand it would run for about 10 minutes before erroring out on “low flow”. A few hours on te phone with Peak SCientific they originally thought it was the H2 cell, that would have been $1-2 k fix. Apparently the tech talked with another senior and found out this model was notorious for a bad resistor. This is not your typical little on-board one but a honking unit with it’s own heat sink. While we are on the phone I was looking up the part number while the tech was looking up the price. To my relief when he came back he said “great news, we have the part in and it’s much cheaper!” Only $400 for a resistor and some wiring. But I had foudn teh resistor for $3.50 online by then and just bought three.

Finally everything turned on and… 10 minutes in it errors out. It would pressurize the unit but whenever it started to flow to the GC it errored out low flow again. I did some straight up Sherlock Holmes work and traced the issue to a solenoid. I found one to replace it and when it came it was 110 instead of 24 volts so I called the company. Apparently I had just purchased the very last 110 solenoid in the world. After some searching he found the only 24 V solenoid left in the world but I would have to do some creative wiring. Done and done!

End result is about 1/5-1/10th of the price of a pre-fab unit but there was some blood, sweat and tears involved. The moral of the story is things can be had cheap if you look around and can use a multi-meter.

Oh yeah, as for the GC I bought new ferrules, septa, column and standards. The thing just worked. SRI GC’s may not be the hyper accurate device you may want but they are built lke a rock, and the support guys are rock stars.

[square_root_pharms]

Thanks for the info! Im sorry id must have gotten the terminology wrong.

[square_root_pharms]

I just watched this video and it was great for a newb: Fundamentals of GC Columns Training – Agilent Technologies - YouTube

[doc_simple]

inetresting. My instrument has a split port but when I spoke woth the SRI guys they never metioned it. I wqould call them directly, and if you do please let me know the results.

I’m an arrogant know-it-all but thats only because I try to learn when I don’t actually know it all

doh! and then I noticed something. It splits the sample into 2. I would have to assume this leads to to different sensors. If they both lead to the same FID that wouldn’t affect a change… at least not the desired one.

[cyclopath]

I’ve seen a single column split to two detectors using that gizmo.

My understanding is you could also split to two columns (and hence 2 detectors).

you can also mount a second injection port. & up to 6 detectors if you’ve got the correct board to pass that data on to your computator. they really are tanks.

[doc_simple]

my unit only has one hookup for FID, though they may make other options. Honestly the guys over there just gave me a method to do terps and cannabinoids on one column. As this is just in house how accurate do I need to be? If you question the results run 4 runs and average.

[square_root_pharms]

i think that low and slow method with 1 FID sounds ideal! especially if you can resolve cannabinoids and terpenes on the same column/detector.

I wouldnt mind finding one with an DELCD detector and trying to resolve pesticides. i imagine for every pesticide i wanted to resolve i would need to make a standard for it? could i simply make my own standard with like avid, forbid, neem oil, etc?

also i found this other unit for sale for 2500.00 any idea what all it might have installed? looks like a purge and trap valving and 3 FID’s

[doc_simple]

i dont think you need the trap. I owuld call SRI and ask them if it will work. It it will a GC with 3 fid’s is a find.

I am going to list my spare here but it has a TCD and I have the two of the wax columns for terpenes. In this machine I would consider the terpene column (and not just because I am selling a couple!) as you have multiple detectors.

SRI 8650C with TCD - $700 Restek Wax Columns, New $175 each

Hey all, I have a spare 8650C. It has a TCD detector so it is not good for cannabinoids. Maybe someone has a use for this detector? I also have two new Restek wax columns for terpene analysis. One is crossbond carbowax polyethylene glycol the other is labeled crossbong PEG. Seems the same to me $175 each The GC is problematic on this board but the columns are a steal if you need one. They run like $750 new. here is a link to the images: https://drive.google.com/drive/folde…

[Beaker]

https://www.ebay.com/itm/Cannabis-Testing-SRI-8610C-Gas-Chromatograph-FID-complete-w-computer-software/163157536028?hash=item25fcf26d1c:g:2AwAAOSw3opbUQbc
@cyclopath, @drPaul, @doc_simple, et al. what is your take on this unit?

My prime goal is self education and to learn but I am only really interested in cannabinoid profiles atm. Suitable?

[square_root_pharms]

Mr XXXX,
If we guess that a 18 year old gc is working fine, then you have most of the hardware.

We can’t do pesticides, the detection limit is too low.

You would need two columns for the potentcy and residual solvents.

Here are a couple videos showing the model 310. The 8610 is similar.

SRI GC Training

Look at the video for the 310 mm cannabis. You would need h2 gas from a cylinder because you dont have a h2 generator.

Greg

On Thu, Nov 1, 2018 at 10:24 AM xxxxxxx zzzzsdfase@sbcglobal.net wrote:

I am looking to outfit a used 8610c for possible cannabis
testing. Cannabinoids, terpenes resid. solvents and possible pesticides
(if this is possible with an additional DELCD, for Abamectin,
Bifenazate: Hydrazine carboxylic acid, Spiromesifen, neem oil, etc)

the pics are of a unit i found for sale on ebay would you be able to tell me what this
unit is outfitted with as far as options, columns, detectors based on the attached pictures?

[square_root_pharms]

that would work from what ive found but it seem like a similar setup could be found cheaper. the software is free and that computer isnt really worth anything so youre essentially paying 5k+ for a barebones 8610c with an FID

[drPaul]

I have used the DELCD detector from SRI for analysis of chlorinated solvents (trichloroethylene, chloroform, etc.) purged from groundwater (an application using those 10-port valves), with the goal of at least a 5 ppb LOD. I would be pleasantly surprised if one of these could hit 10 ppb LODs for pesticides relevant to cannabis testing.

The DELCD worked in my case, but lost sensitivity in a relatively short period, never really got to the desired detection limits reliably, and the replacement detector element (a “consumable” :0) ran hundreds of dollars.

It seemed to crap out whenever I needed to do a demonstration! The proper response being: “I’ve never seen it do THAT before!” This is known as the “Demo Effect.” Works for software demos, too. Especially in front of groups.