Sulfur is known as one of the five ubiquitous elements of steel, and the addition of sulfur reduces the performance of steel. Therefore, the sulfur content in steel must be strictly controlled. In this study, we have been focusing on the iron separation–barium sulfate gravimetric method (JIS G 1215-1) specified in the Japanese Industrial Standards (JIS) as an absolute analytical method for the determination of sulfur in steel. In our previous paper, we demonstrated that the rinse process using hot water in JIS G 1215-1 causes dissolution of barium sulfate (BaSO4), resulting in a significant decrease in recovery. Therefore, suppressing the dissolution of BaSO4 during the rinse process specified in JIS G 1215-1 has been critical issue in this analytical method. In this paper, we aimed to establish a novel rinsing method to replace the conventional hot water rinsing. As a result, it was found that rinsing with an ethanol solution of acetic acid effectively removed excess Ba2+ and Cl− without dissolving BaSO4. With this novel rinsing method, the conventional problem of reduced recovery caused by the rinse process was resolved, and quantitative recovery of the BaSO4 precipitate was achieved.
Soma et al. (Thu,) studied this question.