the eluent
flow was guided to 6130 quadrupole mass spectrometer (Agilent
Technologies, USA) with electrospray ionization ion source (ESI).
Ionization in the ESI mode was performed, using a drying gas temperature
of 350 C, a drying gas flow of 12 L/min, a nebulizer pressure
of 50 psi and a capillary voltage of 3000 V