Determination of alkali and alkaline earth metal ions in blood serum by capillary electrophoresis with indirect UV detection

A capillary zone electrophoresis (CZE) method with indirect UV detection wa s developed for the fast and quantitative determination of alkali and alkal ine earth metal ions in blood serum. Baseline separation of ammonium, potas sium, sodium, calcium, magnesium and lithium cations was achieved within 7 min. Carrier electrolyte consisted of 5 mmol l(-1) imidazole and 1 mmol l(- 1) 18-crown-6 at pH 3.33. The effect of the pH and the concentration of ele ctrolyte on the resolution and the efficiency of separation was investigate d. Also, the effect of the addition of several supramolecular compounds suc h as cyclodextrins and crown ethers, to the electrolyte was studied. During the optimisation of the separation conditions two injection systems: hydro static and electrokinetic, were examined. The application of electrokinetic injection creates the described method fast and convenient, with good prec ision, for migration times from 0.4% to 0.7% and for signal of magnitude fr om 0.4% to 3.1%, high efficiency from 165000 to 5200000 theoretical plates and acceptable detection limits at submicromolar level. The described metho d was applied for the analysis of blood serum samples without the pretreatm ent procedure other than dilution. The quantitative results suggested this method to be useful for clinical applications.