Evaluation and revision of ISO 4937 titration method for determination of chromium
Revision of ISO 4937 Steel and cast iron-Determination of chromium content-Potentiometric or visual titration method has been approved by the methods of determination of chemical composition sub-technical committee of ISO technical committee steel(ISO/TC17/SC1)at the 32nd meeting.The revision project intends to use ISO 5725 and ISO TR 21074 to analyze the international precision results of ISO4937,recalculate the precision of visual titration and potential titration,and evaluate the scope of ap-plication of the method to meet the current analytical needs and technical realities.This paper mainly intro-duces the statistical and evaluation process of the experimental results of visual titration and potentiometric titration in the revision of ISO 4937.The F-test is used to compare whether there are significant differ-ences in the precision of the two methods in the detection of samples with different vanadium content.The results show that the precision of visual titration is significantly different from potentiometric titration when determinating samples with vanadium content greater than 6 mg in test portion.Through this revi-sion,the visual titration procedure of ISO 4937 is also applicable for samples with 3-6 mg vanadium content in test portion,which expand the applicable scope of visual titration method.Through the re-statistics and evaluation of precision,the reproducibility and reproducibility of the revised would be significantly im-proved compared with the original version.
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