This document specifies a methylene blue spectrophotometric method for the determination of sulfur in steel and iron. The method is applicable to sulfur contents between 0,000 3 % (mass fraction) to 0,010 % (mass fraction). However, niobium, silicon, tantalum and titanium interfere in the determination of sulfur. Depending on the contents of the interfering elements, the application ranges and test portion masses given in Table 1 apply