Phosphorus is an important macronutrient and the accurate determination of phosphorous species (namely phosphate) in environmental matrices such as natural waters and soils is essential for understanding the biogeochemical cycling of this element, studying its role in ecosystem health and monitoring the compliance with legislation. This paper is focused on phosphate determination in seawater. Thus, the sources, occurrence and importance of phosphate together with several aspects regarding the analysis and terminology used in the determination of this element in the ocean are briefly described. Existing and future
analytical techniques for the determination of phosphate in seawater are presented. Today’s
phosphate monitoring is dominated by different spectrophotometrical analyzers. Thus, a description of the basis, advantages and disadvantages of the different existing analyzers is provided. It seems that these techniques may be replaced in the near future by electrochemical sensors which provide excellent possibilities for phosphate determination with high precision, long lifetime, low detection limit and good reproducibility. Additionally, electrochemistry allows going further in miniaturization, provides a decrease in energy requirements and avoidance of additional reagents. Recently developed electrochemical methods for phosphate determination will lead to the first
autonomous sensor (ANESIS) which will fulfill all these expectations.