Benzenesulfonamide, 4-[(5-cyano-1,2-dihydro-6-hydroxy-4-methyl-2-oxo-3-pyridinyl)azo]- can be analyzed by this reverse phase (RP) HPLC method with simple conditions. The mobile phase contains an acetonitrile (MeCN), water, and phosphoric acid. For Mass-Spec (MS) compatible applications the phosphoric acid needs to be replaced with formic acid. Smaller 3 µm particles columns available for fast UPLC applications. This liquid chromatography method is scalable and can be used for isolation impurities in preparative separation. It also suitable for pharmacokinetics.