High-Performance Separation and Determination of Co(III) and Ni(II) Chelates of 4-(2-Pyridylazo)resorcinol at Femtomole Levels by Capillary Electrophoresis

Separation of 4-(2-pyridylazo)resorcinol (PAR) and its chelates of CoIII, FeII, NiII, and VV was accomplished within 6 min by simple capillary electrophoresis (CE) with a spectrophotometric detection. The detection limits, defined as 3σ of base-line noise were 1.80 × 10−7 mol dm−3 for CoIII and 1.41 × 10−7 mol dm−3 for NiII chelates, and those on a mass basis were 1.08 fmol (63.6 fg) and 0.84 fmol (49.3 fg) in 6.0 × 10−9 dm3 sample, respectively. A guideline on the ligand design for the CE system is also obtained from the pH dependence of the separation behavior of PAR chelates.