Identification and determination of NH4+ ions in D-Ala-NH2∙HCl drug substance by Ion Chromatography (IC)

Sammanfattning: The quality control laboratory at PolyPeptide has been performing analysis based on ion chromatography (IC) of peptides. A method for separation of negative ions (acetate, chloride etc) is already in use. Lately there has been a need for developing a method to separate positive ions, like ammonium ions, in peptides. The task of this project was to develop a method for ion chromatography, suitable for determination of ammonium ions in the substance D-alanine amide, hydrochloride (D-Ala-NH2∙HCl). The D-alanine amide, hydrochloride is an amino acid derivative used as starting material for chemical synthesis of peptides. These peptides are used as active pharmaceutical substances. It is most possible to find ammonium chloride in amino acids substances which content amid group, as D-Ala-NH2∙HCl. The ammonium chloride is formed during the synthesis of these amino acid derivatives. The reason for analysing ammonium ions is that there is some risk to find undesired impurities in the product. These impurities are difficult to remove.