Protein by Dumas Method

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Price of the test:

$26 per analysis

Acceptable Matrices:

This method is universal for the determination of nitrogen content and can be used for nearly all food products.

Unacceptable Matrices:

Pure oils and shortenings cause fires in the instrument and almost always must be assayed by the Kjeldahl method.

Limit of Detection:

0.1% Nitrogen

Limit of Quantitation:

0.125% Nitrogen
0.648% - 0.798% Protein (factor dependent)

Sample Size Requirements:

20 grams


Protein/Nitrogen by combustion analyzer.

Reportable Units:

% Protein

Turn Around Time:

10 Business Days

Is Rush Available?


Method Reference:

AOAC 992.15; AACC 46-30

Method Description:

The sample is completely combusted at high temperature in the presence of pure O2 (99.9%). Combustion products are H2O, CO2, NOx, and N2. Water vapor, oxygen and CO2 are removed from the resulting gas stream by a series of thermoelectric coolers and chemical sorbents. NOx is reduced to N2 when passed through a column that is packed with hot copper. The resulting N2 is passed to a thermal conductivity detector where it is quantified (helium is the carrier gas). Protein is then calculated from the nitrogen content using a published conversion factor (e.g. 5.70 for wheat).

Additional Information:

Available Protein Factors:
6.25 - general purpose food products/ingredients (Default) except as noted below
5.70 – wheat, wheat flour, and wheat flour breads
6.38 - dairy
5.46 - peanuts and brazil nuts
5.18 - almonds
5.30 – Other tree nuts coconuts (butternuts, cashews, chestnuts, hazelnuts, hickory nuts, pistachios, walnuts, pecans.)