Determination of potassium, sodium, calcium and magnesium in total parenteral nutrition formulations by capillary electrophoresis with contactless conductivity detection

A simple method based on capillary electrophoresis with a capacitively coupled contactless conductivity detector (CE-(CD)-D-4) was developed for the determination of potassium, sodium, calcium and magnesium in parenteral nutrition formulations. A hydro-organic mixture, consisting of 100 mM Tris-acetate buffer at pH 4.5 and acetonitrile (80:20, v/v), was selected as the background electrolyte. The applied voltage was 30 kV, and sample injection was performed in hydrodynamic mode. All analyses were carried out in a fused silica capillary with an internal diameter of 50 mu m and a total length of 64.5 cm. Under these conditions, complete separation between all cations was achieved in less than 4 min. The CE-(CD)-D-4 method was validated, and trueness values between 98.6% and 101.8% were obtained with repeatability and intermediate precision values of 0.4-1.3% and 0.8-1.8%, respectively. Therefore, this method was found to be appropriate for controlling potassium, sodium, calcium and magnesium in parenteral nutrition formulations and successfully applied in daily quality control at the Geneva University Hospitals. (C) 2010 Elsevier B.V. All rights reserved.