Fig. 3
A typical chromatogram of standard drug mixture samples. Chromatographic conditions were acetonitrile-0.05 mol·L−1 potassium dihydrogen phosphate (phosphoric acid to adjust pH to 4.0); the acetonitrile content was varied. a. acetonitrile content 30; b. acetonitrile content 34; c. acetonitrile content 36; d. acetonitrile content 38; e. acetonitrile content 40