[en] This report contains experimental results of two separate subjects: Solubility products of crystalline PuO₂ and amorphous Pu(OH)₄ separation of Np oxidation states with continuous electrophoretic ion focusing, which are presented separately in part A and B, respectively. The new solubility products of Pu oxide and hydroxide are determined to be log K_sp=-60.20±0.17 and -57.85±0.05, respectively. The free energy of formation for Pu(OH)₄(am) is -1141 kJ mol^-1. The chemical speciation method using continuous electrophoretic ion focusing has been examined to separate Np(IV) and Np(V) in the picomol contraction under different experimental conditions, i.e. varying pH, complexing agent and medium conductivity. A successful separation of Np ions of two important oxidation states is demonstrated. (orig.)