Table 1.

Chromatographic conditions of the gradient HPLC method.

Time (min)	Eluent A (%)	Eluent B (%)	Flow rate (ml min−1)
0	30	70	0.8
1	40	60	0.8
2	60	40	0.8
5	65	35	0.8
7	70	30	0.8
8	30	70	0.8

Eluent A: acetonitrile; Eluent B: phosphate buffer at pH 7.3.