Vortex-assisted liquid-liquid extraction combined with field-amplified sample injection and sweeping micellar electrokinetic chromatography for improved determination of b-blockers in XXXX urine.

@entity1169 @entity1 @entity3208 @entity1042 @entity71549 @entity1405 @entity3440 @entity214
A new micellar electrokinetic chromatography (MEKC) method was developed and validated for the analysis of @entity1405 and @entity1169 in @entity1 urine samples. In this study, vortex-assisted liquid-liquid extraction (VALLE) coupled with field-amplified sample injection and sweeping was employed for biological sample clean-up and sensitivity enhancement in MEKC. After VALLE, the urine samples were analyzed by MEKC. @entity71549 buffer (60mmolL(-1), pH 2.0) containing 40% (v/v) @entity1042 was first filled into an uncoated fused- @entity3440 capillary (56cm, 50  m i.d.). The pretreated urine sample was loaded by electrokinetic injection (10kV, 250s). The stacking and separation were performed using @entity71549 buffer (30mmolL(-1), pH 3.0) containing 30% (v/v) @entity1042 and 50mmolL(-1) @entity3208 ( @entity214 ) at -25kV. Detection was carried out at 195 and 214nm for @entity1405 and @entity1169 , respectively. The suggested method is linear (r(2)>= 0.997) over a dynamic range of 0.005-1  gmL(-1) in urine. The intra- and inter-day relative standard deviation and relative error values of the method were below 20%, which shows good precision and accuracy. Finally, this method was successfully applied to the analysis of real urine samples.
