Fig. (2) Chromatogram of the analysis of basic drugs using the Acquity CSH-phenyl hexyl particles. Peaks obtained: 2-aminopyrazine (1), Pindolol (2), Quinine (3), Quinine impurity (4), Labetolol (5), Diltiazem impurity (6), Diltiazem (7), Verapamil (8), Amitryptiline (9)