Method for determining related substances of andrographolide

The invention provides a method for determining related substances of andrographolide. According to the method, HPLC (High Performance Liquid Chromatography) is used for determination; a chromatographic column with octadecylsilyl silica gel as filler is used; mobile phases A, B and C are water, acetonitrile and methyl alcohol, respectively, then gradient elution is carried out; flow velocity is 1mL/min, the detection wavelength is 200-260, the column temperature is 25-40 DEG C, the volume ratio of mobile phases at gradient 1: A:B:C is 60-75%: 25-35%:0-5%; and the volume ratio of mobile phases at gradient 2: A:B:C is 55-70%: 25-35%:5-10%. The method is simple to operate and good in stability and can be used for quickly and accurately determining contents of raw materials of andrographolide and related substances of preparations of andrographolide.