DETERMINATION OF SODIUM, POTASSIUM, CALCIUM AND MAGNESIUM CATIONS BY CAPILLARY ELECTROPHORESIS COMPARED WITH ION CHROMATOGRAPHY

Capillary ion analysis (CIA) is a young analytical methodology adapted to analysis for inorganic ions, and has some remarkable advantages ov er ion chromatography (IC). In this paper a CIA method used for analys is for K+, Ca2+, Na+ and Mg2+ in water samples is presented, and the f actors affecting the separation - such as electrolyte ion, complexing or chelating agents - are discussed. Also the repeatabilities of the m ethod, linearities and the detection limits are compared with those ob tained by IC. Sufficient separation of the four ions is achieved with an electrolyte solution of 5 mM imidazole/6.5 mM alpha-hydroxyisobutyr ic acid/2 mM 18-crown-6 ether, pH 4.1. Detection is by 'reverse' absor bance measurements.