Liquid chromatography of uranium complexes of tetradentate Schiff bases

Dioxouranium together with copper(II), nickel(II) and iron(II) were extracted in chloroform as complexes of bis(salicylaldehyde)-dl-stilbenediimine (dl-H2SA2S) or bis(salicylaldehyde)-meso-stilbenediimine (meso-H2SA2S), and separated by liquid chromatography with UV detection. The linear calibration range and detection limits were 40 - 200 ng and 10 ng/injection for each metal ion. The method was applied to the determination of uranium from mineral ore samples at concentrations of 30 - 700 microg/g with coefficients of variation from 3.6 to 5.5%. The relative elution of dioxouranium complexes of different Schiff bases was examined from reversed-phase HPLC; the substitution of methyl and phenyl groups at the bridge position enhanced the column retention of uranyl complexes.