Zorbax rrhd sb c18

Determinations of exact mass were performed on a UPLC system (1290 Infinity II, Agilent, Santa Clara, CA, USA) connected to qToF mass spectrometer (MaXis Impact, Bruker, Billerica, MA, USA). Separation was done with RP-column (Zorbax RRHD SB-C18, 1.8 ​μm, 2.1 ​× ​100mm, Agilent, Santa Clara, CA, USA). Flow rate was 200 ​μL/min and the gradient elution of the UPLC with (A) ultra-pure water 0.1% formic acid (B) and acetonitrile was as follows: 0 ​min: 95% A; 5 ​min: 95% A; 11 ​min: 85% A; 22 ​min: 50% A; 25 ​min: 20% A; 30 ​min: 20% A; 35 ​min: 95% A; 40 ​min: 95% A. Mass spectrometry parameters in the positive mode were as follows: housing 25 ​°C, nebulising gas 180 ​°C, capillary 4500 ​V. Single ion monitoring (SIM) scanned from 50 to 700 ​m/z. MS/MS collision energy was 10 ​eV. Online calibration was done using sodium formate clusters injected at the beginning of each run for 30 ​s.