Total nitrogen (TN) is one of the key parameters to describe the environmental status of aquatic ecosystems. This parameter is included in most national and international monitoring programs and determined by a large number of laboratories. For the comparability in monitoring programs it is essential that the results produced by different laboratories are comparable. To achieve this, different quality assurance systems were established on laboratory, national and international scale. One point in this quality assurance system are interlaboratory studies between laboratories, which should prove that the different methods or modifications of methods applied will give the same results.

This interlaboratory study was performed within the project: Verbesserte Bestimmung des Gesamtstickstoffgehalts in Süßwasser-, Brackwasser- und Seewasserproben - Validierung der Analyseverfahren.