ABSTRACT
The suitability of the Winkler method for the estimation of oxygen dissolved in water is well established (Standard Methods of Water Analysis, 1936; Fox & Wingfield, 1938). Its usefulness in the field, however, is limited by the fact that it is necessary either to titrate the iodine solutions in the field, or to carry back to the laboratory numerous samples of water. Moreover, the titration of iodine solutions necessitates the frequent standardization of the sodium thiosulphate solution. With the modification of the Winkler method described here, the oxygen content of water can be estimated quickly and easily in the field without bulky apparatus. As no standard solutions are required the method is particularly useful when estimations are made only occasionally.
The disks and the Lovibond Comparator in which they are used are obtainable from Tintometer, Ltd., Milford, Salisbury.
The error due to the oxygen content of the reagents is larger in the syringe pipette method than in the ordinary Winkler method. The difference is not taken into account as we do not consider it significant.
