... effects of changing the organic–aqueous ratio, the pH of the aqueous phase, the flow rate of the mobile phase and the temperature of the column on the retention time and on the shape of the AMFZ and ... One of the most important tasks of a chromatographic analyst in pharmaceutical R&D is the development of analytical methods for the assay of pharmaceutical products and validation of the methods ... Ph.D Thesis CHALLENGES OF HPLC METHOD DEVELOPMENT AND VALIDATION FOR THE ASSAY OF COMBINED DRUG PRODUCTS Éva Kalmár, Pharm.D Supervisors Prof György Dombi, Ph.D., C.Sc...