An Agilent 3D CE system with diode

An Agilent 3D CE system with diode array detector (DAD)
(Agilent, USA) was employed for all experiments in this
study. 50lm ID fused silica capillaries (Yongnian Inc.,
Hebei, China) with a total length of 35 cm (30 cm to the
detector) were utilized for CZE analysis, and the temperature was maintained at 258C. The other operating conditions are as follows: applied voltage 15 kV, DAD UV
detection at 270 nm. Samples were introduced under
pressurized injection at 8 psi6s (1 psi = 6897.76 Pa).
The capillary was conditioned daily by purging first with
0.5 M NaOH (10 min), then with deionized water (4 min),
and finally with the running buffer (4 min). Between consecutive analyses, the capillary was flushed with the running
buffer (2 min) in order to improve the migration time and
peak shape reproducibility