[High performance liquid chromatography and capillary electrophoresis investigation of the neww immunostimulant tetrapeptide drug, thymocartin].

High-performance liquid chromatographic (HPLC) and capillary electrophoretic (CE) methods have been developed for the separation of 22 related peptides (potential and real impurities) from a new immunostimulant tetrapeptide derivative (thymocartin, Arg-Lys-Asp-Val) being under clinical examination. The described methods are suitable for the purity control of the bulk drug material. In the course of the reversed-phase ion-pair HPLC separations C-18 columns (Hypersil BDS and Ultrasphere IP) were used. In the case of using sodium hexanesulphonate as the ion-pairing reagent, the eluent contained phosphate buffer (pH = 3) and 32% v/v methanol, while in another method a gradient system with a sodium perchlorate solution (pH = 2 set by perchloric acid) and acetonitrile was applied. The optimum separation in the CE investigations was achieved at pH = 3 using triethylammonium phosphate buffer and 10% v/v acetonitrile as the organic modifier.