The oxygen dissolved in sea water is usually determined by the classical method of Winkler. Probably because of the large number of investigators who have used this method, there have developed various modifications in the method of collecting samples, in the standardization of the sodium thiosulfate solution, and in the titration of the samples. It is the purpose of this paper to discuss these various methods, the sources of possible error, and to present the best procedure for standardization of the sodium thiosulfate solution.
Thompson, Thomas G., and Rex J. Robinson. 1939. "Notes on the determination of dissolved oxygen in sea water." Journal of Marine Research 2, (1). https://elischolar.library.yale.edu/journal_of_marine_research/539