The method describes the indirect estimation of manganese volumetrically using thiocyanate and pyridine. In a standard measuring flask a known aliquot of manganese solution is taken to which is added pyridine and an excess of a standard thiocyanate solution. Manganese gets precipitated as Mn Py4 (SCN)2. The solution is filtered and the measured aliquot of the filtrate, after acidifying, is treated with an excess of standard silver nitrate solution. The excess of silver nitrate is then back-titrated with standard thiocyanate solution using ferric alum as the indicator.
In the separation of Mn from Fe, the latter is quantitatively precipitated as hydroxide by treatment with slight excess of pyridine. The precipitated iron is removed by filtration and the manganese in the filtrate is estimated as described above. Quantitative results for Mn are obtained by double precipitation.