Abstract
A photometric method for the determination of a small amount of hexathionate has been developed, a method depending on the formation of thiocyanate equivalent to the hexathionate, and on the determination of thiocyanate with an excess of ferric iron. A buffer solution is first added to a standard hexathionate solution in order that the pH of the mixed solution after the addition of the cyanide solution may be within an optimum range; otherwise the hexathionate undergoes alkaline decomposition as a result of the higher pH value caused by the addition of the cyanide. The conditions under which the reaction of hexathionate with cyanide is rapid and proceeds well to completion, have been established by varying the cyanide amount, the pH, the reaction time, and the temperature. Hexathionate can be determined by exactly the same procedure as that used for phentathionate.

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