Extraction with long-chain amines--VI. Separation of manganese as Mn(CNS)4-(6) complex and its complexometric determination in calcareous material.
Manganese is quantitatively extracted into a benzene solution of trioctylmethyl-ammonium chloride from a solution at least 0.25M in potassium thiocyanate and at pH 2.5-7. After stripping into dilute ammonia containing triethanolamine (TEA) and hydroxylamine hydrochloride, manganese is determined by EDTA titration. Calcium and magnesium are not extracted even in traces. Iron is co-extracted with manganese and is masked with TEA during the stripping. Aluminium also does not interfere. In the aqueous phase, after the extraction of manganese, calcium or magnesium can be determined by the usual EDTA titration. The method described permits highly selective individual determination of manganese and calcium and/or magnesium in all materials rich in manganese.