Problems with wine analysis

[minopausa Ulisse Nobody]

Hello,

here is my configuration:

- Light: Halogen 20W
- Desktop Spectrometer 3.0
- No IR lens
- cuvette 4 ml as the image
- red wine



The cuvette in contact with the slit of the spectrometer.
No problem without the cuvette: the spectrum is ok as in the image. The problem is when I put inside the cuvette the red wine.
I see a total reduction of the total light in the visible range. Where I am wrong?



I am stuck at this point and I can't move on with the analysis. The wine is red, clear and there aren't element in suspension.
Please, can You help me? Thanks,

mino

[Jeffrey Warren]

Hi, Mino - it's possible the red wine is simply too opaque -- have you tried diluting it with water, or using a narrower cuvette so that the light path is not so deep?

Jeff

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[Gretchen Gehrke]

Hi Mino, 

If your wine is not in a cuvette, what is the holder you are using (in the "Without Cuvette" experiment)?  Do you know what is the material of the cuvette? 

Best, 
Gretchen

[minopausa Ulisse Nobody]

From these answers I understood that I have to manage this problem alone and do not share the results. Ok, maybe next time :) My team work hard all night and we find the f****ng problem. Now we are building the solution.
Here are the answers:

Hi, Mino - it's possible the red wine is simply too opaque -- have you tried diluting it with water, or using a narrower cuvette so that the light path is not so deep?

Are you serious? Do you think the wine contained in a 4ml cuvette is "opaque"? I will just take only experiments about "opaque" elements  on publiclab:

http://www.publiclab.org/notes/ygzstc/07-23-2014/detection-of-added-sugar-in-red-wine-using-visual-light-spectroscopy
http://www.publiclab.org/notes/cfastie/10-10-2013/lycopene
http://publiclab.org/notes/wagnerc4/02-05-2014/fat-percent-in-milk

If your wine is not in a cuvette, what is the holder you are using (in the "Without Cuvette" experiment)?  Do you know what is the material of the cuvette? 

As shown at http://publiclab.org/wiki/spectral-workbench-calibration and shared on this forum hundreds of thousands of times, you can't use a spectrometer without a calibration.
We calibrated the spectrometer with a 30W Mercurial fluorescent bulb (there isn't a cuvette involved, no holders, and so on. Just the spectrometer and the buld): no problem.

Of course we know the material of the cuvette: It is made in polymethylmethacrylate and is the same that is used in the absorption spectrometers in all analysis laboratories.
We know the absorption curve, we know what is the absorption in the visible. We have analyzed the absorption in the real case and we have seen that is practically the same of the absorption curve.

mino

[Jeffrey Warren]

Hello, mino - I have to ask you to please watch your tone on this list. 

Not only have we offered help and asked for more clarification about your setup in good faith, we are also careful not to assume what you do or do not know about running spectroscopic experiments, as is important in a DIY community where not everyone shares the same background. 

"too opaque" is of course a relative term, but as the light blockage you show in your spectrum is wavelength specific, it seems that my suggestion was quite plausible -- if the major difference between your two spectra is the presence of wine, it does seem that you are attenuating or dimming the input light too much with your sample -- the wine. I recommend you try a dilution or a brighter light. If you can share a spectrum of one of these proposed solutions and it does not work, we can try something else.

I'm sorry you're frustrated, but that's no excuse for rudeness, and if you continue, you risk being moderated on this list. I also suggest that if you are intent on "managing this problem alone and not sharing the results" that a collaborative open source community like Public Lab may not be what you're looking for. 

We are of course happy to help troubleshoot if you are respectful and civil.

Best,

Jeff

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[minopausa Ulisse Nobody]

I don't understand what are you talking about... "tone"? "frustration"??? Can you be a little more precise? :D
You don't notice the white noise increment in the second spectra (ok, not your work) but you noticed a "frustration" in my text... Wow: maybe you have to invent an emotional spectrometer.

Sorry for you: you can moderate me if you want but if you write a stupidity like "it's too opaque" I have all right to think and to say: "Ok, my fault. Maybe I can solve this without your help." You cannot answer with "You will be moderated".
Moreover I helped interlocutors  linking reference guides (without frustration).

Just to resume:

Can you help me? -> It's too opaque -> Wow I don't think so! Read the guides! -> You'll be moderated

Maybe this is better:

Can you help me? -> It's too opaque -> Wow Thank you master (Thinking: "oh my God... he is stupid") -> Ok, you will survive

If you prefer this just tell me, Master.

[Jeffrey Warren]

I'm sorry, but calling others' contributions to the discussion "stupidities" is disrespectful, and I have banned you from this group. 

Apologies to everyone else on the list; feel free to email me off-list with questions, or to continue the discussion. 

Thanks,

Jeff

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