Description |
LC analysis was performed on the Waters ACQUITY UPLCTM System. Samples were injected into an ACQUITY bridged ethyl hybrid (BEH) C18 column (100× 2.1 mm i.d.,1.7μm;Waters,Milford, MA, USA),and the column temperature was set at 40 ℃.The mobile phase consisted of A (0.1 % v/v formic acid in water) and B (0.1 % v/v formic acid in acetonitrile). The gradient conditions of the mobile phase were as follows: 0 min,99.5 % A; 10.0 min, 20 % A; 10.01 min, 0.5 % A;12.0 min, 0.5 % A; 12.1 min, 99.5 % A; and 14.5 min, 99.5 % A. The flow rate was 0.30 mL/min. UV–visible absorption spectra of samples were determined using a photodiode array (PDA) detector in the range of 200–600 nm. The sample injection volume was 1μL. MS detection was performed on a Waters Xevo G2 QTOF mass spectrometer with an electrospray ionization (ESI) interface (Waters). Full scan mass spectra were recorded through a range of 50–1,500 m/z. Nitrogen was used as the nebulizer and auxiliary gas; argon was utilized as the collision gas. The ESI source was operated in positive and negative ionization modes with a capillary voltage of 3 kV, sampling cone voltage of 25 V, cone gas flow of 50 L/h, desolvation gas flow of 800 L/h, desolvation temperature of 450 ℃, source temperature of 120 ℃, and CID energy ramped from 10 to 50 eV. Tandem MS analysis was performed using fast data directed analysis (FastDDA), which is rapid automated, intelligent MS/MS data acquisition for targeted qualitative analyses. |