Applications of capillary zone electrophoresis in clinical chemistry Determination of low-molecular-mass ions in body fluids

Abstract

Investigations were carried out on parameters influencing separation selectivity in the capillary zone electrophoresis of inorganic cations. Copper sulphate can be recommended as a carrier electrolyte salt for the separation of alkali and alkaline earth metal ions. Its separation selectivity is different from that of the widely used aromatic amines and it is compatible with indirect UV detection at 214 nm. The addition of organic solvents to the electrolyte results in a general increase in the migration times of divalent cations relative to monovalent cations. Ion-pairing reagents such as sodium dodecyl sulphate were found to exhibit specific effects on some ions (especially strontium and barium), but are less useful owing to interferences with the separation of alkali metal ions by sodium introduced with the ion-pairing reagent. Applications to the determination of cations relevant in clinical chemistry are demonstrated for serum samples. Further, the determination of anions in serum was investigated using chromate as electrolyte. Generally, the advantage of capillary zone electrophoresis over ion chromatography can be seen in the fact that proteins need not be removed from the sample and do not interfere with the separation of low-molecular-mass ions.