Capillary electrophoresis with a diamine EOF modifier as an approach for glutamine dipeptide containing formulations

Currently, glutamine is thought to be conditionally indispensable amino acid. However, the use of glutamine in clinical practice encounters serious problems related to its limited solubility and instability in water solutions. Therefore, glutamine-containing dipeptides, which have better solubility and stability in the solution, have been introduced into the medical practice. High concentration of L-alanyl-L-glutamine in the medicinal product and thermal sterilization during the manufacturing process are the reasons of many impurities formation--the products of deamidation, racemization, cyclization etc.. The purpose of the study was to develop a single step CE method that could be applied in the purity control of L-alanyl-L-glutamine containing parenteral infusions instead of three routinely used LC methods. After systematic optimization separation conditions were selected: 100 mM borate buffer at pH 8.5 with 0.4 mM diaminopropane as EOF modifier. The method developed allows the separation and determination of the main component and the related impurities. The results show that the method is suitable for quality control of glutamine dipeptide solutions offering some advantages over routinely used LC methods.