On August 31, 2012 Irja Helm successfully defended her PhD Thesis High accuracy gravimetric Winkler method for determination of dissolved oxygen at Institute of Chemistry, University of Tartu. The essence of the work is development of a highly accurate gavimetric Winkler titration procedure for determination of dissolved oxygen content in calibration medium for optical and amperometric dissolved oxygen sensors.

Dissolved oxygen (DO) content in natural waters is a very important parameter. Recent studies show decrease in DO content in several areas of world oceans. Processes leading to this decrease are not completely understood and it is very important to be able to measure DO content very accurately for studying the dynamics of these processes. Amperometric and more recently also optical oxygen sensors are widely used in DO measurements. These sensors need calibration and therefore solutions with accurate DO concentration are necessary. And this is where Irja’s method will be very useful.



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