适用于测定铁含量，以Fe2 O3表示，大于0.020%（m/m）。包括通过碳酸钠和硼酸的碱性熔融溶解试验部分。用硝酸溶液溶解残渣，用氯化羟胺还原铁（III）。在pH值介于3.5和4.2之间的缓冲介质中形成铁（II）-1,10-菲罗啉络合物。在约510 nm波长下对有色络合物进行光度测量。

Applicable to the determination of Fe contents, expressed as Fe2 O3, of more than 0.020 % (m/m). Covers the dissolution of a test portion by alkaline fusion by means of sodium carbonate and boric acid. Dissolving of the residue with nitric acid solution and reduction of iron(III) by means of hydroxylammonium chloride. Formation of the iron(II)-1,10-phenanthroline complex in a buffered medium at a pH between 3.5 and 4.2. Photometric measurement of the coloured complex at a wavelength of about 510 nm.