Protein (Dumas) Test

For a majority of samples, Dumas and Kjeldahl have great accuracy. Some industries prefer one test method over the other, and there are some instances where Kjeldahl may be a better testing choice such as samples containing high levels of fat. It is important to understand the specific industry and regulation requirements for your product and goals for testing.

The Dumas test is a test to measure Nitrogen content, which is then converted to a Crude Protein value using conversion factors. Due to this, any ingredients or compounds that have Nitrogen, but are not in fact protein, will impact the accuracy of this test. Nitrates, creatine, concentrated vitamins, and urea are examples of common compounds that can cause issues. If your product contains any of these ingredients, please reach out to Customer Service before submitting samples for testing.

The Dumas method is based on a fact that is common across amino acids and proteins: amino acids contain Nitrogen. Instead of measuring the amino acids and proteins directly, the Dumas method measures the amount of Nitrogen in the sample when combusted. A protein factor is used to convert the amount of Nitrogen into a Total Protein value. The Protein Factor is determined based on the type of sample and the source of protein.

The Dumas test can be used to determine the Total Protein (crude protein) in a sample, as well as the amount of Nitrogen. This can be used for nutrition labeling, as long as a protein claim is not being made.
The Dumas test does have limitations. Solvents, such as alcohol, and samples high in fats/oils can create fire hazards. The Kjeldahl method is a better choice for these types of samples.
The Dumas method, similar to Kjeldahl, is not a true protein test. Any nitrogen-containing ingredients or compounds can lead to inaccurate results.

The Dumas test can be used to determine the Total Protein (crude protein) in a sample, as well as the amount of Nitrogen. This can be used for nutrition labeling, as long as a protein claim is not being made.
The Dumas test does have limitations. Solvents, such as alcohol, and samples high in fats/oils can create fire hazards. The Kjeldahl method is a better choice for these types of samples.
The Dumas method, similar to Kjeldahl, is not a true protein test. Any nitrogen-containing ingredients or compounds can lead to inaccurate results.

Both Kjeldahl and Dumas are crude protein methods that measure the amount of Nitrogen that is then converted to a Total Protein Content. The principle is the same, however, the chemistry used to measure the Nitrogen is different.
Dumas uses combustion to release nitrogen gas and nitrogen compounds. The nitrogen compounds are separated and reduced to N2 gas while passing through various catalysts and systems.
The Kjeldahl method uses strong acids and catalysts to form nitrogen-containing compounds, such as ammonia. The nitrogen content is then typically measured through titration.

The Dumas method offers several advantages vs. Kjeldahl. Some of the advantages include:
-Faster testing time and better efficiency in testing. This allows for quicker testing.
-Reduces the need for strong acids and toxic catalysts (like Mercury sulfate), which is a gain for human safety and environmental impact.
-The above advantages also translate into lower testing costs for our clients.

We make every effort to keep our methods and detection limits up to date according to the latest standards and qualifications. If you have any questions regarding the limit of detection/quantification or method references, please contact our Customer Service team at 1-800-245-5615.

Our standard turnaround time is 10 business days for most assays. There are some assays that require a longer turnaround time. We also offer a RUSH service that is half the time of the standard turnaround time of the assay at double the cost of the assay. A few assays that we provide cannot be rushed due to the nature of the test. Please check the specific assay you are interested in regarding the ability to RUSH the turnaround time.