Quantification was carried out with Agilent 1100 Series HPLC/DAD System with Nucleodur 100–5-C18 ec column
(250 mm 4 mm with a guard column) from Macherey–Nagel. An injection volume of 5 lL and flow rate of 0.4 mL/min was used and the column temperature was maintained at 20 C. The mobile phase consisted of 0.05% TFA in water as eluent A and 100% acetonitrile as eluent B. The gradient elution started with 20% of eluent B for the first 20 min, increasing to 30% eluent B till 25 min and further increasing to 99% eluent B until 27 min and then decreased to 20% eluent B at 32 min. Compounds were detected and quantified by UV absorption at 280 nm. Quantification was achieved by individual calibration curves (external) from the standard