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MPDC (Unregistered Guest)
Unregistered guest
Posted on Thursday, May 11, 2006 - 4:33 am:   

If there is not always product in front of your probe, this can give noise. A possible solution is to scan over a longer timeframe and average more spectra. Another possibility is that your product is simply too dark and not enough light comes across. Most spectrometers will allow you to record in a single-beam mode, showing clearly how much energy reaches your detector. Note that noise due to a moving product is not necesarily an unsurmountable problem for a good calibration. Much will depend on your other variations, s.a. temperature and chemical composition. Mathematical treatments are not miracle treatments! Look at the proces with your spectrometers eyes, i.e. in the rawest form possible. Try to understand what your spectrometer sees, and you will be one step closer to a solution. Metals will normally reflect all NIR radiation equally and will therefore not have a spectral signature. They can of course work like (focussing) mirrors or diffuse reflectors.
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FHLONG (Unregistered Guest)
Unregistered guest
Posted on Wednesday, May 10, 2006 - 3:35 pm:   

Nathalie,

There are several things that could make things look noisy. Does the original spectrum look noisy ? Sometimes second derivatives will increase the noise if the raw spectrum does not
have sufficient signal to noise. There are seveal ways that you might deal with issue of not
having dough in the view of the spectrometer at all times.

Fred
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Nathalie Fa (Unregistered Guest)
Unregistered guest
Posted on Friday, May 05, 2006 - 5:01 am:   

Hi,

I have done a measurement of the mixing time of dough by NIR, and then, applied several mathematical functions (second derivative, negative function, integration of the peak). But my results are VERY noisy ! Can someone help me to explain this noise? Is it possible that a signal from the metallic bowl containing the dough interfere with the signal comming from the dough? The dough is in continuous movement during the measurement and it is not always in the way of the NIR beam...

Please let me know if you have any idea ! Thank you in advance!

Nathalie
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Nathalie Fa (Unregistered Guest)
Unregistered guest
Posted on Friday, May 05, 2006 - 4:45 am:   

Hi,

I have done a measurement of the mixing time of dough by NIR, and then, applied several mathematical functions (second derivative, negative function, integration of the peak). But my results are VERY noisy ! Can someone help me to explain this noise? Is it possible that a signal from the metallic bowl containing the dough interfere with the signal comming from the dough? The dough is in continuous movement during the measurement and it is not always in the way of the NIR beam...

Please let me know if you have any idea ! Thank you in advance!

Nathalie
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Eric LALOUM
Posted on Monday, March 25, 2002 - 1:50 am:   

Hi,

2 questions about process applications :

a) where would be the best position to insert a NIR probe into a batch reactor containing melted polymer
(polyurethane) agitated with an helix ?

bottom, middle, up ?

b) how can we avoid that the probe is stained by the product ? is there any anti-adhesive coating that could be placed at the edge of the probe ?

Thanks for your help,
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Michel Coene (Michel)
Posted on Thursday, May 02, 2002 - 2:21 am:   

a/ Probably bottom. Main point is to avoid air-bubbles.
b/ Oh, the beautifull world of self-cleaning, non-sticky and other magical probes-windows-....

My advice: don't wait until pigs start flying, get a probe that will resist whatever you use to clean the reactor, and make it easy to reach and dismantle. If the product does not put a thick sticky layer on a looking-window, you might consider dropping the probe altogether and measure using a FreeSpace system pointed at a sapphire window in the reactor wall.
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Ian Michael (Admin)
Posted on Tuesday, May 07, 2002 - 7:58 am:   

I just want to remind all users of this forum that commercial postings are expressly forbidden. This is designed to avoid an every-increasing number of commercial postings as one manufacturer responds to another. I have deleted the previous message in this thread as being too commercial, and invited the author to resubmit the reply without the product-specific parts.

If you are in any doubt as to whether your posting is commercial, then don't make it. Post a neutral reply inviting private responses to you by e-mail.

I would also remind everyone that you can, usually, get information on the poster by clicking on their name (to the left of the message). This is either a mailto link or a link to their Profile. If you have registered on this board you have a Profile, where you can control your Preferences for this Forum such as whether you receive e-mail notification of posts and, indeed, whether your e-mail address is publicly available or not. There is also the option to include personal information, including a link to your personal home page.

I would encourage everyone to review their Profile if they haven't done so. If you can't remember your password, use the Password Maintenance option in the Utilities menu on the far left.
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W. Fred McClure (Mcclure)
Posted on Tuesday, May 07, 2002 - 9:03 am:   

As President of the Council for Near Infrared Spectroscopy, I must concur with Ian Michael on the matter of commercial comparisons. NIR Publications has graciously agreed to let the NIR community use their website, so we do not want to put them in an awkward position by making commercial comparisons in this medium. We can do this between ourselves on a one-on-one basis via personal email.
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Bruce H. Campbell (Campclan)
Posted on Tuesday, May 07, 2002 - 2:15 pm:   

I agree with Ian and Fred. We need to keep this forum free from commercial messages. I further agree with Ian that if you are involved in a commercial enterprise, such as selling equipment, you should not tout your equipment. You have the opportunity to contact the person directly.

Bruce Campbell
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Salvador Garcia
Posted on Wednesday, May 15, 2002 - 8:36 am:   

I hope this is not too comercial to ask:

What is the aprox retail price for an NIR probe to be used on-line inside a batch reactor ?

I'm a student, and vendors usually don't like students so public forums are my only resource.

Thanks for your time and answer.
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Michel Coene (Michel)
Posted on Thursday, May 23, 2002 - 12:55 am:   

I don't sell probes so I will leave exact prices to others, but prices will depend very strongly on what you want to measure. You should specify these things: max temp and pressure in the reactor; presence of acids or other chemicals which can cause corrosion; presence of organics which can dissolve seals.

Between your standard probe and the 500°C 200 Pascal knock-down-an-elephant-super-probe with 99.99% pure gold seals, the price difference will be more then just a few percent....
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hlmark
Posted on Friday, May 24, 2002 - 9:13 am:   

I have information to communicate to Eric which is probably too commercial to put on the discussion group, so if Eric sends his e-mail address to me I will be glad to discuss an alternative with him

Howard

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