Direct electrochemical flow analysis system for simultaneous monitoring oftotal 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 nitr ite content in nonfiltered seawater samples is demonstrated. The complete s ystem has been optimized to operate within the ammonia and nitrite concentr ation range of 0.05-10 ppm. The system offers good reproducibility (< 5%) a nd stability (< 0.02 ppm/h) at constant temperature, while the analysis tim e is in the order of 1.5-4 min depending on the sample analyzed. The analys is results of seawater samples obtained with the FA system were compared to that obtained with the standard colorimetric method and establish the suit ability of the analyzer for the precise and continuous measurements of untr eated samples for both in field and laboratory applications. In addition, i ts small size and weight offer the advantage of portability, while its data logging capabilities also allow for independent ammonia and nitrite monitor ing. (C) 2000 Elsevier Science B.V. All rights reserved.