Short Note #45: Nitrogen and Protein Determination in Pharmaceuticals

A simple and fast procedure for nitrogen determination in pharmaceuticals according to the Kjeldahl method (semi-micro), as described in the European Pharmakopeia 6.0 / 2.05.08, is introduced in this study. Protein determination is calculated The sample is digested with sulfuric acid using the SpeedDigester K-436 or K-439, followed by distillation and titration with the KjelFlex K-360. There are no differences between the results obtained with the K-436 and the K-439 respectively.

Introduction: Nitrogen determination is one of the key analyses performed in quality control. The samples require digestion with sulfuric acid to convert nitrogen into ammonium sulfate. After conversion to ammonia through the alkalinization with sodium hydroxide, the sample is distilled into a boric acid receiver by steam distillation, followed by a titration with hydrochloric acid solution. The nitrogen content is multiplied by a sample-specific factor to obtain the protein content.

Sleeping Pill Samples

Sleeping Pill Samples


Experimental Instrumentation: SpeedDigester K-436, K-439, KjelFlex K-360

Samples: Sleeping pills and tranquilization drops

Conclusion: The determination of nitrogen contents in pharmaceuticals according to Kjeldahl using SpeedDigester K-436, K-439, and KjelFlex K-360 provides reliable and reproducible results with low relative standard deviations.

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