Experimental conditions:
Instrument: Trisep-2010 GV CEC system;
Column: 200 mm×100μm I.D. capillary packed with 3μm C18;
Mobile phase: 5 mM phosphate buffer in 50% methanol;
Applied voltage: -3 kV;
Pressure applied on column: 14Mpa;
Injection volume: 20 nl;
Detector wavelength: UV 254nm;
Peaks: 1. resorcinol; 2. catechol; 3.m-cresol; 4. p-cresol; 5. 2-nitrophenol