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The HPLC chromatogram of chlorogenic acid (1) in the root of I. helenium (Column, Hypersil C18 column (200 mm × 4.6 mm); mobile phase, acetonitrile: 0.1% phosphoric acid (10 : 90); flow rate, 1 mL/min; column temperature, 30°C; wavelength, 327 nm; injection volume, 20 μL).
