For LC-MS analysis, 0.1 mg sample was dissolved in 1 mL water in a HPLC vial. Samples were analyzed using a HPLC Agilent 1200 series system coupled to an ESI-Orbitrap-MS (Thermofisher LTQ Orbitrap XL). The LC analyses were carried out using a Grace reversed phase GROM-Sil-ODS-4-HE column (50 x 2 mm, 3 µm). Samples were analyzed at 20 °C and at three wavelengths (λ = 215 nm, 280 nm, 350 nm). A flow rate of 0.3 mL min -1 was applied. The gradient was linearly increased from 80% 0.1% HCOOH in water and 20% 0.1% HCOOH in ACN to 100% 0.1% HCOOH in ACN in 10 min. The mobile phase composition was held for 3 min at 100% 0.1% HCOOH in ACN. Finally, the initial conditions were restored and maintained for 5 min. The raw data was analyzed using FreeStyle (Thermo Scientific).