The used chromatograph system was a Waters 510 HPLC with
a 486 Tunable Absorbance Detector and a Rheodyne 7725i manual
injector (USA), and a Prevail Amino column (150 4.6 mm, 5mm,
Alltech, USA) was used for the separation with a C18 guard
cartridge (48 mm, Phenomenex, USA)