Liquid scintillation counting of calcium-45 in plant and soil material

The recovery efficiencies of 45Ca, for plant material using dry ashing with HCL as the extractant, and for soils using column extraction with MgCl2 as the extractant, have been determined. The extraction and detection procedures, using available scintillation solvent systems, are given and show a combination of a high counting efficiency with high recovery efficiencies. The extraction procedures are simple, involving minimal operator time, and allow simultaneous 45Ca determination in both plant and soil material. Both extraction procedures exhibit good reproducibility over a wide range of specific activities while being relatively insensitive to quenching and carrier calcium normally encountered in plant and soil material. These procedures are particularly useful in ecological studies requiring the examination of a large number of plant and/or soil samples over a wide range of radioactive concentrations. (U.K.)