The flow rate was 1 mL/min, and the injection volume was 20 L. Column temperature was maintained at 40C. A Prodigy 5 'm ODS (3), 100 ! (250 & 4.6 mm) column from Phenomenex was used (Torrance, CA). Solvent A was 100% acetonitrile. Solvent B was 10% (v/v) acetic acid and 1% (v/v) phosphoric acid in water. Allsolvents were LC grade. The program used a linear gradient from 2 to 20% solvent A in 25 min; then a linear gradient of solvent A from 20 to 40% in 5 min, with simultaneous detection at 520 and 280 nm. Peak areas were used to calculate percent purity based on LC, at both wavelengths.