High-performance liquid chromatography (HPLC) determinations were conducted using a 1.0 mL min 1 methanol/water flow
with a gradient from 40% to 90% (v/v) methanol in 15 min, and
then 90% (v/v) methanol was run during 5 min. A 20.00 μL
injection volume was employed. Measurement wavelengths were
256 nm for CPPU.