Kjeldahl nitrogen determinations are performed on a variety of food substances. The Kjeldahl method may be broken down into three main steps: digestion, distillation, and titration.

1. Digestion: is accomplished by boiling a homogeneous sample in concentrated sulphuric acid. The end result is an ammonium sulphate solution.

2. Distillation: excess base is added to the digestion product to convert the ammonium salt to ammonia.

3. Titration: the amount of nitrogen in a sample can be calculated from the quantified amount of ammonia in the receiving solution. The ammonia is captured either with a carefully measured excess of a standardised acid solution (back titration) or a boric acid solution (direct titration)

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VWR can offer different heating systems, with flexibility in volume (from 100 ml to 800 ml) and in the number of samples too...


VWR offers different distillation systems for different budgets, ...


From simple burettes to fully automated, programmable titration systems from Schott and Mettler....