Table 1.

Time (min)	Water (0.02% o-phosphoric acid) %	Acetonitrile %
0	94	6
25	70	30
30	70	30
30,01	0	100
35	0	100

Column: Supelcosil LC-18 (250 × 4.6 mm, 5 μm).

Mobile phase: water (0.02% o-phosphoric acid) and acetonitrile were used in gradient elution.

Flow rate: 1 mL/min.

Detection: 254 nm (diode-array detector).

Injection volume: 10 μL.