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Moon Sun (Msdr)
New member
Username: Msdr

Post Number: 1
Registered: 3-2006
Posted on Wednesday, March 29, 2006 - 3:32 am:   

HI,
I just found this discussion. At present I am also in need of the cholesterol spectra from 600-1000nm.
Where should I search?
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Nuno Matos (Nmatos)
Posted on Tuesday, July 12, 2005 - 2:32 am:   

Dear All,

I'm starting a new project by implementing a probe in a reactor to monitor a determined reaction. However I'm facing a problem: When the pressure increases and decreases (necessary to sampling) I loose signal intensity (about 3 times). The only way to recover the signal is increasing the pressure. But when it decreases the signal looses intensity. I'm talking in increasing the pressure 0.5 bar in a very low pressure reaction.
The probe is placed at the bottom (1/3 of the height) between the two helix and in the middle of two baffles.
Could anyone tell me what I'm doing wrong?

Thanks

Nuno
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MPDC
Posted on Tuesday, July 12, 2005 - 2:46 am:   

What are you measuring? Liquid or gas? Are you using a transmission or transflection probe? Is the probe certified to work at these pressures? Either you get more product in the path because your product easily compresses, or your probe is bending out of shape. A good possibility for the first option is there are air/gas bubbles in your liquid, effectively decreasing pathlenth. When you increase pressure, the bubbles disappear and there comes more liquid inside your probe.
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Nuno Matos (Nmatos)
Posted on Tuesday, July 12, 2005 - 2:54 am:   

First of all, thank you for your reply.

I'm measuring liquid. I'm using a transflection probe. The probe is certified to work at these pressures.

There isn't any bubbles in the liquid. That was my first thought. Even if there were any bubbles the agitation would refresh the signal.

Nuno
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Bob Rosenthal
Posted on Thursday, July 14, 2005 - 7:55 am:   

Bruce Campbell's List: I Need Help in Obtaining NIR Cholesterol Spectra

I would appreciate learning where there might be published NIRsSpectra of cholesterol. Although I am interested in cholesterol spectra anywhere in the NIR region, my primary interest is in the short wavelength region between 700 and 1100 nanometers.

NIR cholesterol spectra is needed for inclusion in a paper that has been accepted in the medical journal "Circulation."

Thanks in advance,

Bob Rosenthal
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hlmark
Posted on Thursday, July 14, 2005 - 9:21 am:   

Bob - have you asked Karl? I seem to recall that he had measured spectra of many blood and body components, and I'm pretty sure that Cholesterol was among them. He might even be able to tell you where he published it (if he did), or where someone else might have published a spectrum

Howard

\o/
/_\
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hlmark
Posted on Thursday, July 14, 2005 - 9:46 am:   

Here's another idea, that I got from Emil: Jerry might have some spectra from the time he was at Argose. You can ask him.

\o/
/_\
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hlmark
Posted on Thursday, July 14, 2005 - 10:16 am:   

I got curious and did a web search. There are some Raman spectra out there, and some NMR spectra but apparently no NIR spectra.

\o/
/_\
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Tony Davies (Td)
Posted on Friday, July 15, 2005 - 5:09 am:   

Hi Bob,

I've just checked the JNIRS database. I think Rob Lodder is your man. If you have access to Anal Chem you could check Anal Chem 65, 1247 (1993).
Best wishes,

Tony
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hlmark
Posted on Friday, July 15, 2005 - 8:07 am:   

Bob - Tony must not have actually checked the article himself. It has spectra of LDL and some other blood/body components, including APO and spectra through an aorta, but no cholesterol as such.

\o/
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hlmark
Posted on Friday, July 15, 2005 - 8:09 am:   

Bob - Tony must not have actually checked the article himself. It has spectra of LDL and some other blood/body components, including APO and spectra through an aorta, but no cholesterol as such.

Rob, however, is another likely source for a spectrum, as is Jim Drennen.

\o/
/_\
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vitas
Posted on Tuesday, July 19, 2005 - 2:21 am:   

By chance I have remembered DR skin spectroscopy accessory published in Appl Optics vol. 34 p. 610-21 (1995). Publication contains 1100-2500 nm spectra of a few compounds of clinical interest. Cholesterol is included.

Maybe it helps

Regards,
Vitas
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Bob Rosenthal
Posted on Wednesday, July 20, 2005 - 10:49 am:   

Cholesterol Spectra

I would like to thank everybody that responded to my request for cholesterol spectra. I received not only answers from the discussion web site, but also a large number of private e-mails from members of the discussion group.

All your suggestions and help are sincerely appreciated.

Again, thanks.

Bob Rosenthal

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