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dafna barkan (Dafna)
Posted on Sunday, October 12, 2003 - 3:51 am:   

Does anybody have any knowledge about NIR calibrations for aminoacids?
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Peter Tillmann (Tillmann)
Posted on Monday, October 13, 2003 - 1:38 am:   

Dear Dafna,

there are some publications, but they are spread and not consistently. The only source to my knowledge with tradition are the Degussa people in Hanau, Germany. They market calibrations as a customer support.

I personally doubt it is possible to detect animoacids using NIRS. I would go for the Degussa formulars in raw components instead.


Peter
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Gabi Levin
Posted on Monday, October 13, 2003 - 6:41 am:   

Dear Dafna,

I have done some successful work with amino acids
but in solutions of these, not calibration for amino acids within a bio matrix, so not knowing the exact nature of your poject, I can't say more. If you want to contact me by e-mail (see below) I will be able to provide more details. I will also be glad to share the information I have and any experience I gained in some applications.

You can also send me an e-mail to [email protected]

Thanks, Gabi
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W. Fred McClure (Mcclure)
Posted on Monday, October 13, 2003 - 9:24 am:   

Dafna,

There are a couple of references in the literature on amino acids. Send and email direct and I can direct you to them: [email protected]

Fred
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Tony Davies (Td)
Posted on Monday, October 13, 2003 - 2:12 pm:   

Hello Dafna!

I have to say (apart from a few very specialised cases such as methionine) that I have never been convinced about about any claims to measure amino acids in a natural matrix by NIR spectroscopy. The problem is that amino acids are very highly correlated between themselves and the nitrogen content of the sample. Analyses may look good but really they are mainly due to these correlations. The results might not be far wrong most of the time but I suggest that in the case of an unusual sample, where the result really matters, the predictions would continue to be around the average i.e. not a prediction of a problem sample.
But you should tell us a little about your actual problem and perhaps we can be more helpful.
Best wishes,

Tony
PS Before NIR spectroscopy I was an amino acid analyst.
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Bastia
Posted on Thursday, April 08, 2004 - 8:22 am:   

Hello

I am also interested in calibration for AA in natural matrix (animal feeds).
Indeed the question of the correlation with protein is a problem.

We have started to work a little on this challenging topic. Does anybody have more information on this kind of topics ?
Thank you
Denis Bastianelli
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Theo van Kempen
Posted on Sunday, December 26, 2004 - 8:15 am:   

In these messages it keeps coming back that AA are highly correlated with protein. Have you ever looked at these correlations? Data shows that they are VERY poor for most feedstuffs, and I would not rely on them (even the technical people from Degussa will agree with this). In fact, both NIRS and FTIR can get much better prediction errors than correlations based on CP. Is this because IR sees AA? In the case of FTIR one can proof this fairly easily. For NIRS, who knows.

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