The Kjeldahl Method

Developed in 1883 by Johan Kjeldahl, the Kjeldahl method in analytical chemistry is used for the determination of nitrogen contained in organic substances. Today, the Kjeldahl method is the worldwide standard for calculating nitrogen and protein content in a wide variety of samples from:

Food & Feed: Grain, meat, fish, milk, dairy, fruit, and vegetables

Beverages: Juices and water

Environmental: Agriculture, oilseeds, soil, fertilizers, water, wastewater, and sludge

Chemical & Pharmaceuticals: Paper, textiles, rubber, plastics, and polymers.

Kjeldahl Digestion Systems: The VELP Solution

The VELP Scientifica line of Kjeldahl digesters are designed to optimize automation workflows for laboratory staff and provide ideal conditions for reproducible results. Additionally, VELP Scientifica's automatic and semi-automatic Kjeldahl digesters are designed to be both economical and ecologically sustainable.

Automatic Digesters

In Kjeldahl analysis, sample preparation plays a crucial role towards the formulation of accurate results. With the DKL series of automatic digesters, manual operations have been drastically reduced: the lowering and lifting of samples, as well as the separation between test tubes and suction cup all take place fully automatically.

Automatic Distillation & Titration Analyzers

VELP Scientifica offers fully automatic Kjeldahl Analyzers (distillation units with integrated colorimetric titrator or connectable potentiometric titrator) that are ideal for determining ammoniacal nitrogen, protein determination, nitrogen content (Kjeldahl or direct alkaline distillation), nitric nitrogen (after reduction/Devarda), phenols, volatile acids, cyanides and alcohol content with possible connections to autosampler.

Webinar: Kjeldahl & Dumas Methods in Class N/Protein Determination

The Dumas and the Kjeldahl methods are the primary techniques used in N/Protein determination. Many decision makers and users are undecided between the two methods. Watch this VELP Academy webinar dedicated to Nitrogen and Protein determination method to help laboratories choose the one that best method that suits their needs. 


Gulf Scientific Corporation (GSC) is a leading provider of complete laboratory solutions in the fields of analytical, life and material sciences. Founded in 1990, GSC is headquartered in Dubai, United Arab Emirates, with regional offices and supply chain distribution centers across the Middle East.