An appropriate replacement for oxygen in water

[hazzna]

I am trying to model the behavior of oxygen in water. However there is so little oxygen in water I don't think I could measure concentrations of it experimentally.

Does anyone have advice on what I might be able to use as a replacement for oxygen?

I need to find something (a gas?) that is more soluble in water then oxygen, which is of similar size to O2, which I can more easily measure experimentally.

Thanks!

[Dr_Morbius]

At standard temperature and pressure the concentration of O2 in water is about 8.3 ppm. Its easy to measure. You can do a titration using the Winkler Method. You can also use an electrochemical sensor to do it.

http://serc.carleton.edu/microbelife/research_methods/environ_sampling/oxygen.html
http://en.wikipedia.org/wiki/Winkler_test_for_dissolved_oxygen