Abstract: A method for determining the concentration of dissolved oxygen in a water sample comprising the steps:(a) providing a water sample of predetermined volume, the oxygen content of which is to be determined;(b) mixing additives with the water sample to form a mixture, the additives comprising an oxidizable metal salt comprising a transition metal cation selected from the group consisting of scandium, titanium, vanadium, chromium, manganese, iron, cobalt, nickel and copper, and an anion selected from the group consisting of an inorganic anion and an organic anion which, with the cation, results in a water soluble oxidizable metal salt, at least one water soluble alkali metal compound selected from the group consisting of an alkali metal oxide and an alkali metal hydroxide and at least one oxidation-reduction indicator capable of a color change upon oxidation of the metal salt;(c) preventing any substantial contact of the mixture with atmospheric oxygen; and(d) comparing the color of the mixture to a predetermined