Spectrophotometric determination of neptunium(6) in tributyl phosphate solutions

A study was made on spectrophotometyric Np(6) determination in toributylphosphate (TBP) solutions in n-dodecane according to absorption of Np(6) complex with di-n-butylphosphoric acid (DBPA). Values of stepwise constants of stability for complexes with the ratio of M:DMPA = 1:1 and 1:2 are equal to (2.5±0.5)x103 and (8±1)x102 l/mol respectively. The dependence of optical density of complex solutions on Np(6) concentration obeys Buger-Lambert-Ber law in 0.5-10 g/l range. The value of molar absorption coefficient of 1:2 complex is equal to 50±0.5 l/(mol.sm). 2 refs.; 2 figs