Capillary electrophoresis for the determination of N-Acetyltyrosine and N-acetylcysteine in products for parenteral nutrition: Method development and comparison of two CE systems

Summary Because of the problems with stability and solubility, some of the amino acids (AAs) used in parenteral nutrition products are often replaced by their acetylated forms. These include N-acetyltyrosine (NAT) and N-acetylcysteine (NAC). This leads to a need to develop new analytical methods for rapid and easy determination of these substances in the presence of common AAs. Capillary electrophoresis (CE) is one of the techniques that have been successfully applied to the assay of multi-component samples containing AAs and their derivatives. This paper discusses a new CE method for the simultaneous determination of two acetylated AAs in solutions for parenteral nutrition. A background electrolyte (BGE) was developed based on borate buffer with alkaline pH. The method is selective and enables the separation and assay of analytes without special sample pretreatment. Validation parameters confirmed sufficient precision and accuracy of the method. Its applicability was verified by testing several medicinal...