Calling all Eggheads

[verticity]

The papers show how to closely duplicate HPLC results using NIRS. HPLC physically separates the kavalactones so that each can be measured individually by UV spectroscopy. This takes time (about 13 minutes with the method and column I use) and requires sample preparation. NIRS measures the absorptivity (~400-2500nm) of the dry powder (no prep necessary) and gives results in seconds. The advantage is that a large amount of samples can be tested very quickly. The disadvantage is that the NIRS apparatus capable of doing this is costs well in excess of $50,000, where a basic HPLC system can be assembled for around $3000. Also note these papers only describe measurement of kavalactones; to validate the same process for FK's would take much more research.

If I'm understanding you correctly, you are proposing the use of UV spectroscopy (~200-400nm) alone. While this would probably show some different characteristics of different cultivars it can't measure the individual quantities of specific compounds, because they don't react to UV the same as they do to NIR. To quote wiki, "Near-infrared spectroscopy is based on molecular overtone and combination vibrations." Since these vibrations don't occur at UV wavelengths, the approach you're proposing won't work.

Right, we are actually talking about a completely different technique from what is described in the paper. I think it might work. Using the modeling and fitting techniques I outlined above I believe it might be possible to measure individual kavalactones.

Another big problem with NIR reflectance spectroscopy is that since it uses dry powdered samples, the fineness of the grind and texture of the powder could actually effect the spectra. If I had $50K+ to blow on this, I would get a GC-MS instead.

 

[Rick.Sanchez]

@Rick.Sanchez Here are what the published UV spectra of the isolated flavokavains and kavalactones look like. I think the kavalactones are distinct enough that they could be distinguished.
View attachment 7024

Yes. i said that the best bet would be repeating what was done in rhis paper, but

@Rick.Sanchez Here are what the published UV spectra of the isolated flavokavains and kavalactones look like. I think the kavalactones are distinct enough that they could be distinguished.
View attachment 7024

I think you misread what I said. I told OP that repeating that experiment would be his best bet, but it's not a good idea because the equipment is cost prohibitive. Troubleshooting will also be a nightmare for him/her. This is why i think its a bad idea. If OP was a researcher in an O chem, spectroscopic analysis field, or a big player in the kava business, i would suggest cautiously doing lots of homework before investing the money. I'll say it again: Gautz et al had trouble gething anything worthwhile--thats very telling

Also, the ascorbic acid will not help anything. the problem is signal:noise more than distinguishing the different kavalactones. You need sensitive equipment either way.

This just isnt a home project.

 

[HeadHodge]

Yes. i said that the best bet would be repeating what was done in rhis paper, but


I think you misread what I said. I told OP that repeating that experiment would be his best bet, but it's not a good idea because the equipment is cost prohibitive. Troubleshooting will also be a nightmare for him/her. This is why i think its a bad idea. If OP was a researcher in an O chem, spectroscopic analysis field, or a big player in the kava business, i would suggest cautiously doing lots of homework before investing the money. I'll say it again: Gautz et al had trouble gething anything worthwhile--thats very telling

Also, the ascorbic acid will not help anything. the problem is signal:noise more than distinguishing the different kavalactones. You need sensitive equipment either way.

This just isnt a home project.

That's why we need you and your unlimited access to equipment. Admit it, wouldn't researching this be more fun than eating a peanut butter sandwich at lunch reading trashy old spines? Just think of it as working out of someone else's garage.
I'll help you get a govt grant and you can keep the I.P. rights for your future new MegaCorp.

 

[ApéroNoble]

how does an egg have a head

 

[HeadHodge]

how does an egg have a head

It doesn't have a head, it is a head.

You take an egghead and attach it to your body of preference.

 

[ApéroNoble]

That's not very nice HH noone makes fun of you when you take your hat off

 

[verticity]

As you say, these are the isolated KLs and FKs. If you test the spectrum of an un-separated sample at UV wavelengths, you will get an "average" of all nine components (plus a few others), and I doubt much distinction between cultivars/noble/non-noble would be visible.

I've wrangled uglier blobs in my day

 

[verticity]

Yes. i said that the best bet would be repeating what was done in rhis paper, but


I think you misread what I said. I told OP that repeating that experiment would be his best bet, but it's not a good idea because the equipment is cost prohibitive. Troubleshooting will also be a nightmare for him/her. This is why i think its a bad idea. If OP was a researcher in an O chem, spectroscopic analysis field, or a big player in the kava business, i would suggest cautiously doing lots of homework before investing the money. I'll say it again: Gautz et al had trouble gething anything worthwhile--thats very telling

Also, the ascorbic acid will not help anything. the problem is signal:noise more than distinguishing the different kavalactones. You need sensitive equipment either way.

This just isnt a home project.

I don't think signal to noise would be a great problem, actually. The UV absorbances of kavalactones are quite strong. There will be plenty of signal. It's not really a signal-to-noise problem, but a deconvolution problem.

 

[verticity]

As you say, these are the isolated KLs and FKs. If you test the spectrum of an un-separated sample at UV wavelengths, you will get an "average" of all nine components (plus a few others), and I doubt much distinction between cultivars/noble/non-noble would be visible.

Actually, Lebot's paper validating the acetone test already demonstrated this (distinguishing noble vs. tudei) is possible, by looking at the single wavelength of 400nm (right on the hairy edge of the UV). Your own work with visible spectra has also shown this, as you are well aware.

Quote: "At 400 nm, the mean UV absorbance of acetonic extracts from noble, two-days and wichmannii varieties are 0.69, 0.94 and 1.04, respectively. The significant (+0.757**) correlation between the total FK content and the extracts absorbance at 400 nm indicates that a simple colorimeter can be used to detect poor-quality raw material."

I recon if you looked at the entire UV-VIS spectrum from 200-700nm, and used a more sophisticated model, you would be able to get an even more significant correlation.

 

[Rick.Sanchez]

I don't think signal to noise would be a great problem, actually. The UV absorbances of kavalactones are quite strong. There will be plenty of signal. It's not really a signal-to-noise problem, but a deconvolution problem.

I'm guessing your background is math heavy. I can confidently tell you that there is no chance OP will be able to make this work as a home project. Signal to noise is going to be a nightmare with anything other than expensive equipment. That's just one of several major problems with the chemistry.

 

[verticity]

I'm guessing your background is math heavy. I can confidently tell you that there is no chance OP will be able to make this work as a home project. Signal to noise is going to be a nightmare with anything other than expensive equipment. That's just one of several major problems with the chemistry.

My background is experimental, but I do tend to go apeshit with the theory.
I know all about signal to noise problems lol
You can get a decent UV spectrophotometer for less than $1000

 

[Rick.Sanchez]

My background is experimental, but I do tend to go apeshit with the theory.
I know all about signal to noise problems lol
You can get a decent UV spectrophotometer for less than $1000

You need NIRS. I'm not saying it's impossible with uv vis, but it's not realistic for a home project for the reasons I mentioned previously

 

[verticity]

You need NIRS. I'm not saying it's impossible with uv vis, but it's not realistic for a home project for the reasons I mentioned previously

I agree. I am not suggesting to use NIRS as a home project, but UV-VIS. @Deleted User has done some pretty impressive stuff with his home lab and visible spectra in acetone testing. He can easily distinguish noble from tudei kava from the visible spectrum. The S/N ratio is even better in the UV, surely looking there could yield even more information, probably not a complete chemotype, but at least more information than a noble/tudei binary distinction.

 

[Rick.Sanchez]

I agree. I am not suggesting to use NIRS as a home project, but UV-VIS. @Deleted User has done some pretty impressive stuff with his home lab and visible spectra in acetone testing. He can easily distinguish noble from tudei kava from the visible spectrum. The S/N ratio is even better in the UV, surely looking there could yield even more information, probably not a complete chemotype, but at least more information than a noble/tudei binary distinction.

OP said he wanted quantification. I agree that you might be able to get something along those lines, but not what HeadHodge said they were looking for.

 

[verticity]

OP said he wanted quantification. I agree that you might be able to get something along those lines, but not what HeadHodge said they were looking for.

I agree.

 

[Rick.Sanchez]

Glad that's been sorted out!