Rough Estimate of NO3/PO4 from Crude Protein/Lipids

cobra2326

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I did some basic research and it looks like Crude Protein is directly extrapolated from the Nitrogen content. One source said Crude Protein = 6.25 * N [1]. Others had similar numbers. It seems that we should be able to just divide by 6.25 and then divide again by the molecular weight of Nitrogen vs. Nitrate. Does this sound right?

Randy had a great article on Phosphate[2], which directly addressed a puzzling fact that Amino Acids don't have Phosphate, but that most organisms attach it. I'm still not totally sure if we can derive this from the Nitrogen content, however.

That brings us to a few of the other components:

  • Crude Fat (Lipids): these are complex and I have no idea where to begin.
  • Ash: this appears to just be the leftover inorganic "stuff" after heating/oxidizing the organics[3].
As always, input and help is much appreciated :)

[1] https://www.feedipedia.org/node/8329
[2] http://www.advancedaquarist.com/2012/3/chemistry
[3] http://people.umass.edu/~mcclemen/581Ash&Minerals.html
 

Randy Holmes-Farley

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I'm sorry, I'm not following the purpose here?

N is present in a great many biomolecules, one of which is protein.

P is present in DNA, RNA, phospholipids, and phosphorylated proteins, as well as others..
 
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cobra2326

cobra2326

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I'm trying to estimate the rise in NO3, PO4 from a certain amount of added food, based on the quoted min content from the label. In this case: Reef Roids.
 

Randy Holmes-Farley

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In general, I do not think you can make such calculations very accurate from ingredient lists, especially for phosphate.

For the Reef Roids example, since it is very high in crude protein, a rough estimate of the N can come as you suggest from the known nitrogen content of typical proteins. I don't think we can usefully estimate the N content of the other classes of materials listed. Just assume none from them. :)
 
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cobra2326

cobra2326

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Thanks Randy. I had a feeling this was a crazy idea but figured I’d ask anyway
 
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