Waters HPLC controller model number 600 with photo array
detector model number 996 and autosampler model number
717 plus were used. Phenomenex C18 110A Gemini column
(250 mm 4.6 mm 5 lm) was used for the separation. Injection
volume was 10 ll with flow rate set at 1 mL/min and wavelength
set at 214 nm. Mobile phase consisted of methanol: water
(75:25) with 0.075 M of tetrabutylammonium phosphate (PIC-A).