Alpha liquid scintillation measurement of plutonium in solution spiked by236Pu

The liquid-liquid extraction method used with alpha liquid scintillation with rejection of -emission is strongly dependent of the nature of the aqueous solution containing actinides. We propose to measure plutonium quantitatively by its labelling with²³⁶Pu. Two procedures of quantitative extraction have been developed as well as the mathematical fit to obtain accurate results. The limits of detection have been determined for several counting times like for instance 0.2 pg/l after one day of acquisition time. We have applied both procedures successfully for the determination of plutonium in doped drinking water and in solid samples after dissolution.