Determination of Organic Nitrogen in Natural Waters by Means of an Ammonia Probe

Abstract

The use of an ammonia probe for the determination of total nitrogen in river and sea water is described. The ammonia is directly determined in the diluted destruction mixture, so that the time-consuming distillation procedure is avoided. Destruction procedures, which mainly differ in the nature of the used catalyst, were compared. The procedure of Gibs and Moum yielded the best results and was adapted for the low nitrogen content waters.

The difficulties encountered when adapting the method and the probe characteristics are reported. The accuracy of the method was checked by comparing it with a well-established titration method and with a colorimetric method. The final procedure allows good precision and accuracy. The lit for precise measurements is around 0.5 ppm N, so that for sea water the method is not universally applicable.

Key Words:

• Water
• sea water
• potentiometry
• ammonia
• total nitrogen
• organic nitrogen