Help: Protein Determination w/out spectrometer possible?

S.Ballal ballal_sv at hotmail.com
Thu Jul 11 23:19:15 EST 2002


Dear Meei,

One method which I can suggest is "Kjeldahl Test" for total Nitrogen.
This tests estimated the total Nitrogen in a sample assuming that all
Nitrogen present is protein Nitrogen.  But I guess it will require the
use of spectrophotometer !!!!!

It requires a relatively large sample and handling of strong acids.
You can find protocol and references on the web easily. 

This is the method of choice when total protein in complex mixtures
like animal feeds etc. are to be tested for protein quantity. I am
sure for protein estimation in Soy bean meal etc. it will method of
choice.

Best of Luck

S.Ballal
Indus Biotherapeutics Ltd.Ahmedabad
http://www.indusbio.co.in/




"Frank O. Fackelmayer" <Frank at Fackelmayer.de> wrote in message news:<3D2C60E5.5CACABEC at Fackelmayer.de>...
> well, it depends on how accurate the determination must be. Given the
> inherent inaccuracy of all methods due to protein-to-protein variations,
> I suggest you use a colorimetric test (such as Bradford's) and good
> standard samples determined in parallel.
> The test works well between 1 and 12ug protein (e.g. dissolved in 1ml of
> water or buffer). I do standards of 0, 2, 4, 6, 8, 10, and 12ug of BSA,
> which give a nice range from brown to blue. Given your sample is in the
> same range of concentration, a visual inspection of the assay is
> sufficient to say what the approximate concentration is. 
> 
> 
> Frank
> 
> 
> 
> 
> 
> Trexx wrote:
> > 
> > Hi all.
> > 
> > I would like to search for a method to determine protein (crude or
> > otherwise) in soybean meal, and samples similar to soybean meal.
> > 
> > I work in a tiny tiny lab, mainly doing oil and fat analyses. This
> > would be a new test for us. We have no spectrometer. The more
> > sophisticated equipments that we have is a Lovibond tintometer (RYB
> > visual colormeter), and a muffle furnace.
> > 
> > Does anybody have an idea if this is even possible?
> > 
> > Meei



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