Separation of some transition metal ions by high performance centrifugal partition chromatography with bis-2-ethylhexylphosphinic acid

The separation of such metal ions as Fe(III), Zn(II), Cu(II), Mn(II), Co(II), and Ni(II) has been investigated by high performance centrifugal partition chromatography (HPCPC) using 0.16 M bis(2-ethylhexyl)phosphinic acid/heptane as a stationary phase. Acetate, chloroacetate, and tartrate buffers were used as mobile phases. The above six metal ions could be well separated by HPCPC using the step elution method, in which the pH of the mobile phases was changed at fixed elution times. The Co(II) cations present in unrefined Ni(II) sulfate solution could also be separated by this HPCPC method. The sample solution was continuously delivered into the stationary phase by a pump, and the Co(II) cations were found to be preferably retained into the stationary phase. The HPCPC system was operated with 2,136 partition channels, at a rotation speed of 800 rpm, and at a flow rate of 2.0 cm(3)/min.