A Waters 600 controller liquid chromatograph
(Waters Corporation, Milford, MA) equipped with a refractive index (RI) detector (Waters 410) and a Hibar prepacked stainless-steel column (300 × 3.9 mm; Hibar
Systems Ltd., Ontario, Canada), and packed with 10μm
Bondapak-NH2(Waters Corporation) was used for HPLC
analysis, using acetonitrile and distilled water (80:20;v/v)
as the eluent