Table 1.
HPLC apparatus and operating conditions

Items	Conditions
HPLC	Shimadzu JP/LC-10A System/CDD-6A detector
Column	Shim-pack VP ODS (250 4.6 mm)
Mobile phase	Acetonitrile : DDW = 40 : 60 (v/v)
Flow rate	1.0 mL/min
Detector	UV 228 nm, 242 nm
Oven temp.	40°C
Injection volume	10 μL