Simultaneous determination of alkali, alkaline earth and transition metal ions by capillary electrophoresis with indirect UV detection

Determination of metal ions in aqueous samples using capillary electrophoresis can be accomplished with indirect UV detection. For optimal determination of alkali, alkaline earth, and transition metal ions, several electrolyte systems were studied. Detection at 214 nm was performed with a background electrolyte containing reagents with inherent absorbance in the UV range: imidazole, 4-methylbenzylamine and 4-aminopyridine. Glycolic acid and α-hydroxyisobutyric acid were used as complexing reagents. A mixture of 16 metal ions was successfully separated. The detection limits were between 92 ppb for Ca and 454 ppb for Cu with hydrostatic injection. All peaks were completely resolved and well separated. A separation efficiency of about 650 000 theoretical plates per meter was achieved for the Mg ion. The described methods can be used successfully in routine analysis of real samples. One of the methods was applied to an environmental water sample from the Georgian river Kasretula.