Liquid chromatography–electrospray mass spectrometry of multicomponent peptide mixtures: Characterization of a mixture from the synthesis of the hormone goserelin

In order to separate and characterize the target peptide and the side-product peptide compounds of a synthesis mixture of the peptide hormone goserelin, liquid chromatography coupled to high-flow electrospray ionization mass spectrometry (LC–ES-MS) has been used. Goserelin is an important drug with recognized therapeutical application for palliative treatment of prostatic and breast carcinomas. Stepwise solid-phase peptide synthesis commonly results in unwanted side-products associated with incomplete peptide chains. Consequently, this procedure requires extensive purification and characterization of the final synthesis mixture. The method of linear solvation energy relationships has been applied to optimize the proportion of organic modifier of the mobile phase used in the established LC method. On the other hand, ES-MS has allowed rapid and reliable identification of the target peptide and the other impurities present in the goserelin synthesis products.