Abstract
A laboratory method for maintaining the dissolved oxygen (DO) content in corrosion media at any fixed levels below 100ppb was investigated. The nitrogen gas containing a known amount of oxygen gas generated by electrolysis of water with a galvanostat was continuously passed through deionized water and 6% NaCl solution at a temperature of 20°C, and the DO contents were measured by applying both the Winkler analysis and the polarographic method. A equation was presented to calculate the DO content using the value of applied electrolytic current. The results showed that the DO contents analyzed by the Winkler method agreed with those estimated by the equation with the precision of 95% or above for pure water and 90% or above for 6% NaCl solution, and it was certified that this method was very useful in laboratory application for controlling the DO content. The polarographic DO meter made in our laboratory could accurately measure the DO content. Some simplification of calculating equation was discussed. The end point of titration for the Winkler analysis could be precisely determined by applying amperometric titration with Pt and W electrode.
