Amino acids are widely used in medicine, particularly in products for clinical, parenteral and enteral nutrition. The products usually contain a mixture of α-amino acids and derivatives with a composition developed according to the type of primary disease and patient age. Parenteral nutrition is applied to patients in poor conditions when feeding throughout the digestive tract is inappropriate or impossible. Thus the quality and correctness of the formulations is extremely important issue of these products.
The quality control of the products above all requires amino acid analysis. There are a lot of chromatographic methods reported for the purpose with the most popular ion-exchange chromatography in pH-gradient elution with post-column ninhydrin derivatization. The separations usually require a multistep-gradient elution with long conditioning and analysis time. Additionally a few amino acids like tryptophan, cysteine, acetyltyrosine and acetylcysteine are assayed using disparate methods. Capillary electrophoresis is a rapidly growing analytical technique in recent years, especially useful for analyzing complex samples. It offers advantages of high separation efficiency and throughput that contributes to single-step analysis and lowering the costs.
The present study proposes a new method for amino acids determination that can be applied for amino acid profiling in solutions for parenteral nutriton. The MEKC method based on mixed micellar system was developed for the separation of 6-amino- quinolyl-N-hydroxysuccinimidyl carbamate (AQC) derivatized amino acids. Background electrolyte was based on Tris-borate buffer of high alkaline pH. Sodium dodecyl sulphate micelles were modified by use of 1,2-hexanodiol as a co-surfactant. The effect of the modifier on amino acid migration was studied with respect to hydrophobicity of analytes . The modifier appeared suitable to improve the separation of AQC tagged amino acids without adverse effect on buffer ionic strength or EOF velocity. The method was successfully validated and applied for amino acid profiling in medicinal preparations for parenteral nutrition. The results obtained were compared with a reference chromatographic method |