ANALYSIS OF ~(237)Np IN AN EXCESS OF ~(238)Pu

The sample is dissolved in HNO_3 and the Pu and Np in the solution isreduced to Pu(III) and Np(IV) by ferrous sulphamate. Np(IV) is then extractedwith TTA-toluene and back-extracted by 8mol/l HCl. Ferrous ion and arsenazo III isthen added for photospectrometric determaination at 665 nm. The molar absorbanceis 6.3×10~4 and the detection limit is 0.1--0.35 microgram Np with a relativestandard deviation of ±3%.