Capillary electrophoretic separation between Fe(II) and Ni(II) precomplexed with 1,10-phenanthroline in a high concentration buffer of n-butyric acid/n-butyrate and its application

Abstract.

The capillary electrophoretic separation was accomplished for Fe(II) and Ni(II) precomplexed with 1,10-phenanthroline (phen) in 2 M n-butyric acid/n-butyrate buffer at pH 4.5 with direct UV detection at 260 nm. The applied voltage was 5 kV. The high concentration buffer of the n-butyrate resulted in a similar separation mechanism to that of ion-pair reversed-phase high-performance liquid chromatography. The separation would be due to the hydrophobic interaction between the ionic associates, [Fe(phen)₃](n-butyrate)⁺ and [Ni(phen)₃](n-butyrate)⁺, with the n-butyrate ion and n-butyric acid as background electrolyte. Linear calibration ranges were obtained for Fe(II) and Ni(II) from 100 to 500 ng ml^–1. The relative standard deviations (n=10) for 3 g mL^–1 Fe(II) and Ni(II) were 0.090 and 0.086, respectively. Detection limits (S/N=3) for Fe(II) and Ni(II) were 20 ng mL^–1. The method was applied to the determination of nickel in aluminium and duralumin alloys.