Uv-vis spectroscopy

Testing and Analytics
1

Would an older uv-vis spectrometer be a useful tool in getting an idea of TAC in conversions?

It would be real helpful if i could take the guessing out of the equation, bioassay is hard to quantify…

Anyone with experience, i would appreciate response

Pheonix

2

is TAC = total activated cannas?

if so then sure a uv-vis HPLC is what you’re wanting so you can quantify acidic and neutral species. you can also find plenty of GC (FID and MS) methods out there or develop your own, but you will decarb your sample in the injection port > so only neutrals unless you want to deal with derivitization prep

The accuracy and the number of analytes you can measure is very dependent on your sample prep , acquisition method parameters, data quality system, and the standards you have available

1 Like
3

Not the best tool for the job, but certainly better than nothing at all…

The required absorption spectra and extinction co-efficients are around here somewhere too.

Probably want “scan” mode.

@Beaker was using one to guide his work. I inherited it, but lost it in a lab “move” before getting a chance to really play with it.

It’s not gonna give you as much data as TLC would

1 Like
4

still in the MF echo chamber… I might should fix that.

doesn’t look like it will tell you much about CBD vs THC

1 Like
5

This is really useful data for anyone looking to teach their HPLC how to identify compounds in the case of retention window drift.

3 Likes
6

I would hope it’s posted other than in the echo chamber, and even linked to the primary source (which I usually try to do)…but this place is a mess and I don’t feel like digging around atm.

Pretty sure I pulled from a paper that was posted in the data dump. Google lens wasn’t supper helpful…

https://future4200.com/uploads/default/original/2X/a/ade023df12fe133eaa9112daa89cbf91582622cc.pdf

Also has useful info.

Edit: UV vs Diode-Array (PDA) Detectors for (U)HPLC has the same image but is clearly not where I grabbed that figure from.

2 Likes
7

I guess when I spent an afternoon some years ago generating and correlating this data by hand I should have realized I could just google the result and tried that first.

1 Like
8

Thc Delta 9 is somehere around 255 nm, i dont have exact number in my head.
Thank you very much for the replys, i found uv vis machines on ebay for 400 euro so it is tempting

9

Nope. But maximum IS listed in one of the papers linked above.

Issue for conversion work is that the spectra of CBD and THC are very similar (as shown above).

You will get more information out of TLC

10

Ok, Silver nitrate tlc that is?

11

You could just use UV shadowing.

Dig a little…

12

Would it not work if i was sure i consumed all of the cbd?

13

How would you be “sure”?

TLC:

14

Can anyone download a PDF of this paper and post for a definitive basis of discussion?

https://doi.org/10.1016/j.jlumin.2022.119387

I have no idea what that fluroescense abstract is about.
Some of the data is confusing…. A,B what? 230 degrees C or F? They heated “solid d9 “ to this temp?
You could heat solid THCA to 230F and get d9?

“What we’re looking at with the FF is fluorescence after excitation with UV.”

Are you doing fast Fourier transforms of emission spectra?

Regards

1 Like
15

Yeah, just ignore that. “FF” == fraction finder from arometrix…and that thing can’t tell cannabinoids from a hole in the ground.

1 Like
16

oh you mean cuvet style UV - Vis spectrometer without any HPLC or chromatographic front end ? That sounds like a pain in the ass to get not super helpful information lol

You can likely get 8+ tests from an accredited canna analytical lab for your $400 budget

or save up to buy an LC or GC to start your in house analytics

17

Yeah, if you’ve got one laying around, it makes some sense. Buying a used one that is likely obsolete and impossible to get parts for would not be my advice

Edit: to quote @Beaker, the only one I’ve known to play this trick…

2 Likes
18

You might be surprised what you can get parts for / fix with new parts & circuits. I just updated my old single wavelength UV flash system to a UV-Vis scanning PDA with AI molecular recognition that you train during calibration for a couple hundred bucks using old HPLC parts and a parallax propeller chip controller.

Its really just a PDA setup as one diode for more sensitivity and a diffraction grating that it scans through the wavelengths of the UV or Vis source lights with a stepper motor detecting intensity changes at the PDA.

Still was a cool project.

4 Likes
19

Yeah, but you’re not like the other kids…

:shushing_face:

2 Likes