[Simultaneous measurement of 32P and a 33P double-labelled sample by liquid scintillation counter and its application to phosphorus compounds isolated by paper chromatography].

Simultaneous determination of 32P and 33P radioactivities was carried out with the liquid scintillation counter (Aloca LSC 670). For the quenching correction, the channel ratio method was used, and the proper gain and window level were set to get the maximum performance number or Klein-Eisler value. Using this method the radioactivities of the 32P and 33P double labelled compounds which were separated with paper chromatography were determined. New index, RSA (relative specific activity, i.e. 32P/33P) was proved to be effective as well as specific activity for the studies of the transport and metabolism of phosphorus compounds in the plant roots.