Direct electrochemical flow analysis system for simultaneous monitoring of total ammonia and nitrite in seawater

The design and the performance of a new portable flow analysis (FA) system for the continuous, fast and accurate measurement of total ammonia and nitrite content in nonfiltered seawater samples is demonstrated. The complete system has been optimized to operate within the ammonia and nitrite concentration range of 0.05-10 ppm. The system offers good reproducibility (< 5%) and stability (< 0.02 ppm/h) at constant temperature, while the analysis time is in the order of 1.5-4 min depending on the sample analyzed. The analysis results of seawater samples obtained with the FA system were compared to that obtained with the standard colorimetric method and establish the suitability of the analyzer for the precise and continuous measurements of untreated samples for both in field and laboratory applications. In addition, its small size and weight offer the advantage of portability, while its datalogging capabilities also allow for independent ammonia and nitrite monitoring. (C) 2000 Elsevier Science B.V. All rights reserved.