Determination of calcium by radiochemical replacement

Abstract

The determination of calcium ions in solution by radiochemical replacement of silver-110 in labelled solid silver oxalate, cobalt-60 in labelled cobalt oxalate and manganese-54 in labelled manganese oxalate has been examined. A one-to-one replacement was observed with manganese oxalate. The technique can be used to determine 2·5 to 100 µmole ml^–1(100 to 4000 µg ml^–1) of calcium, and the lower limit is reduced to 16 µg ml^–1 by using a 50 per cent. methanol solution. Magnesium interferes to only a small extent. Each determination takes less than 5 minutes, and the precision is ±2 per cent.