Cerenkov and liquid scintillation analysis of the triple label 86Rb---35S---33P

A method was developed for the analysis of 86Rb---35S---33P as a triple-label. The analysis of the total activity of composite mixtures of the three radionuclides was demonstrated to be quantitative by the liquid scintillation efficiency tracing technique with recoveries between 99.7–100.4%. The activity of 86Rb in the triple label was determined by Cerenkov counting in water with a 52% counting efficiency. The combined activities of 35S + 33P were determined by subtracting the activity of 86Rb from the total activity of the triple label. The separate activities of 35S and 33P are obtained by difference after a period of time sufficient for the decay of 33P to negligible levels leaving only residual 35S in the sample. The method described is useful for the analysis of 86Rb---35S---33P as a triple label for the elements K---S---P in studies of fertilize use efficiency.