NOVEL CHROMATOGRAPHY METHODS

摘要

The present invention relates tonovel HPLC methods for the analysis of the API formoterol and related substances. In a first method the mobile phase comprises two or more liquids, and the relative concentration of the liquids is varied to a predetermined gradient. In a second method the mobile phase comprises a first liquid A comprising an aqueous solution of ammonium acetate and a second liquid B comprising a dipolar aprotic solvent. In a third method the mobile phase comprises a first liquid A comprising an aqueous solution of ammonium acetate with a concentration of 0.001 to 0.025M, and a second liquid B. The present invention also relates to a method for analysing a substance, comprising the detection and optional quantification of one or more specific impurities.