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Journal of Automated Methods and Management in Chemistry
Volume 2007, Article ID 49535, 6 pages
Research Article

Using Sequential Injection Analysis to Improve System and Data Reliability of Online Methods: Determination of Ammonium and Phosphate in Coastal Waters

1GKSS Research Centre, Institute for Coastal Research, Max-Planck-Strasse, Geesthacht 21502, Germany
2University of Lueneburg, Lueneburg 21332, Germany

Received 16 October 2006; Accepted 18 December 2006

Copyright © 2007 Carsten Frank and Friedhelm Schroeder. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


This article summarises the advantages of the sequential injection analysis (SIA) for the online determination of nutrients in coastal waters. It concentrates on techniques to improve the reliability of the gained data by continuously monitoring one or more standards and on the advantages of online standard additions and offline determination of manually collected samples with the online SIA system. These measures are advantageous during method development and validation and can be used to verify the system performance on a regular base to reduce the amount of erroneous results. No changes in the flow system are necessary and the sample throughput is only slightly reduced. These techniques have been applied to a SIA system which is able to simultaneously determine ammonium and phosphate at a rate of more than 100 samples per hour each and detection limits (3σ) of 0.06 μM and 0.05 μM. Results from a campaign in summer 2005 are shown.