Determination of dissolved oxygen by the winkler method and the solubility of oxygen in pure water and sea water

Abstract

AbstractValues for the solubility of oxygen in water obtained by a modification of the Winkler method are shown to be low because of losses of iodine vapour. Iodine vapour is also lost in two of the standard modifications of the Winkler method in common use, the amount lost depending on the technique of the analyst.The volatilisation of iodine can be avoided by the use of the alkaline iodide reagent of Pomeroy & Kirschman; a procedure employing this reagent is described. Interference by pitrites and ferric iron may be eliminated by sodium azide and phosphoric acid respectively.The accuracy of the Winkler method, modified to prevent the loss of iodine vapour, has been confirmed using gaseous oxygen as a standard.Using the procedure recommended, determinations have been made of the solubility of atmospheric oxygen in distilled water between 0·4° and 37°, and in sea water between 2° and 27°. The results for distilled water are in excellent agreement with those of Klots & Benson between 2° and 27°; the new values for sea water agree fairly well with those of Fox.In measurements of the rate of solution of oxygen, the approach to equilibrium using these values was consistent with the law of Adeney & Becker.