| Author | Message | |||
     Kenneth Gallaher (ken_g) Intermediate Member Username: ken_g Post Number: 16 Registered: 7-2006 |
Things have gone quiet on this from FDA et al. it is clear they know what happened and are working within China to find out who did it - good luck. The melamine spectrum has lots of structure - it should be possible to spot it at reasonable levels. | |||
| Neil J. Dominy (neil) Junior Member Username: neil Post Number: 9 Registered: 7-2003 |
Hi Bruce, It is a common practise to look for urea contamination in both finished feeds and selected raw materials. This is being done successfully in some cases by NIR. Cheers Neil | |||
| Bruce H. Campbell (campclan) Moderator Username: campclan Post Number: 97 Registered: 4-2001 |
As it appears melamine was added to components of the dog and cat foods, a question arises. This question is, is any program being started (or in existence) that would routinely use NIR for detection of melamine and possibly other materials that would give higher Kjeldahl values for protein in foodstuffs? | |||
| Kenneth Gallaher (ken_g) Member Username: ken_g Post Number: 15 Registered: 7-2006 |
Read This... http://www.cnn.com/CNN/Programs/anderson.cooper.360/blog/ BINGO! | |||
| Kenneth Gallaher (ken_g) Member Username: ken_g Post Number: 14 Registered: 7-2006 |
Thanks for the spectra! OK now you food guys need to tell us if melamine would interfere with a protein analysis...gasoline is more my field... Certainly looks rich enough to interfere with lots of things. One reference I found suggests 2180 is the standard wavelength used - plenty of interference there... | |||
| David Russell (russell) Advanced Member Username: russell Post Number: 32 Registered: 2-2001 |
Here's the Melamine Spectrum as ASCII Pairs. Should be readable just about anywhere. Dave Russell
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| David W. Hopkins (dhopkins) Senior Member Username: dhopkins Post Number: 107 Registered: 10-2002 |
Ken, You should be able to look at the spectrum posted if you have Grams, Pirouette, Unscrambler or Vision software. I don't know about other programs that can read it. Just make sure the file extension is .da. For some reason the file I downloaded had a different extension. Does anyone know of a routine to read the da files in matlab? Tony, I had not tried to assign the peaks, I think it would take a bit of research to do even half of them! That would be an interesting exercise. Melamine is a 6-member aromatic ring structure with alternating C and N atoms, with amino groups attached to each C. Neil's structure is correct but not at all informative. Regarding the question of solubility, we'd need to known what "slightly soluble" means. I had not heard that it was found in dry formulas. Best regards, Dave | |||
| Kenneth Gallaher (ken_g) Member Username: ken_g Post Number: 13 Registered: 7-2006 |
Some additional thoughts. 1) The contaminator confused melamine polymer (harmless - but full of amide and nitrogen) with the monomer - cat/dog killer. 2) the analysis to be fooled was indeed a wet method. 3) The contaminator confused urea (from which melamine monomer is made) with melamine monomer(both white). Urea is toxic too, but perhaps less so. | |||
| Kenneth Gallaher (ken_g) Member Username: ken_g Post Number: 12 Registered: 7-2006 |
Howard, Good Thought! Melamine is C3H6N6 !! Lots of nitrogen... 2/3 by weight! Bet that is it... | |||
| Howard Mark (hlmark) Senior Member Username: hlmark Post Number: 89 Registered: 9-2001 |
I've heard of urea being added to feeds to give a false indication of protein, because that causes both NIR and the Kjeldahl (wet chemical) protein test to read high. A little bit goes a long way - pure urea measures at about 200-300% protein. The Kjeldahl measurement equivalent is about the same, as I recall. \o/ /_\ | |||
| Kenneth Gallaher (ken_g) Member Username: ken_g Post Number: 11 Registered: 7-2006 |
Gary and all, A pdf would be great! I understand up to 6% solid melamine has been seen in dry pet food. Yes it is only slightly soluble in water or alcohol. I had a friend suggest that melamine might have been added to the contaminated wheat germ as a way to fool NIR into a false protein measurement.... | |||
| Tony Davies (td) Moderator Username: td Post Number: 150 Registered: 1-2001 |
Dave, It is a lovely spectrum! How many of the peaks can you assign? Best wishes, Tony | |||
| Tony Davies (td) Moderator Username: td Post Number: 149 Registered: 1-2001 |
Gary, You can find the story at http://www.marketwatch.com/news/story/story.aspx?guid=%7B99479E16%2DBE39%2D4314%2D99C3%2D34D1474C9E3F%7D&dist=rss I think this one will run (the story not the dog)! Tony | |||
| Gary Rollason (nvisible) New member Username: nvisible Post Number: 2 Registered: 2-2007 |
Hi Dave Spec. assay is 100%. (finely divided powder) According to Chemwatch, melamine is only slightly soluble in water. What is the connection with dogfood? Gary | |||
| David W. Hopkins (dhopkins) Senior Member Username: dhopkins Post Number: 106 Registered: 10-2002 |
Hi Gary and Ken, That is a beautiful spectrum. I assume it is a sample of a powder? Does anyone know, at the levels it has been detected in the wet-packaged dog foods, is it in a solubilized state? As a solute in water, it would be expected to have a vastly different spectrum. Thanks for sharing the scan. Best regards, Dave | |||
| Gary Rollason (nvisible) New member Username: nvisible Post Number: 1 Registered: 2-2007 |
Hi Ken Attached spectrum for Melamine (Aldrich B/N 08618A0) Instrument: FOSS XDS with smartprobe. I can send as a pdf if you can't open a .da file. Regards.
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| Tony Davies (td) Moderator Username: td Post Number: 147 Registered: 1-2001 |
Hello Ken, Sorry I have looked in Jerry Workman's book but didn't find it. "Melamine" is in Proc NIR-2003 but it is a paper about varnish on melamine! Hope someone can help. Best wishes, Tony | |||
| Kenneth Gallaher (ken_g) Junior Member Username: ken_g Post Number: 10 Registered: 7-2006 |
Does anyone have a NIR spectrum of melamine monomer that they could share....? |
Melamine.prn