Analysis of Sodium and Potassium in Total Parenteral Nutrition Bags by ICP-MS and ICP-AES:Critical Influence of the Ingredients

Abstract

The compounding of total parenteral nutrition solutions (TPN) in the hospital pharmacy is a high-risk activity for which a quality assurance programme is necessary. The complexity of parenteral nutrition solutions containing almost 50 ingredients makes it difficult to measure each of them. On the other hand, the assay of electrolytes such as sodium and potassium is accepted as a quality marker for estimating compounding errors. Thus, the aim of this study was to estimate the influence of ingredients on the accuracy of assays of electrolytes. Experiments were performed with aqueous working simulated solutions of sodium and potassium prepared by the addition of each nutrient step by step, (dextrose, amino acids, lipids, vitamins and trace elements). Sodium and potassium levels were measured by Inductively Coupled Plasma Mass Spectroscopy (ICP-MS) and Atomic Emission Spectroscopy (ICP-AES). The performance of these methods was compared using statistical evaluations (t-test and Mann–Whitney test).The study highlights the interference of amino acids, vitamins and trace elements when measuring sodium, but no interference was noted during the measurement of potassium. To reduce the risk and to improve the quality of compounding, we used an automated compounding device but, even in this case, the acceptance criterion for sodium and potassium determination was not <10%.