Chromatographic conditions
The separation of BUswas conducted on a Kromasil C18 column
(5mm particle size, 250 mm4.6mm i.d.). The mobile phase was
consisted with ultrapure water and ACN (v/v = 22/78). The
detection wavelength was set at 260nm and the flow rate was
1.0mL min1. The injection volume was 20mL.