毛细管电泳分离法检测新疆紫草中萘醌类成分

建立了新疆紫草萘醌类总成分的毛细管电泳分离方法,考察了检测波长、添加剂类型、进样量和分离电压对分离检测的影响。实验条件为检测波长200nm,运行缓冲液为含20%乙醇的硼酸盐缓冲液(0.1 mol/L,pH 8.0),进样量3.45kPa×5s,分离电压20kV。方法可在20 min内检测到5种活性成分,重现性良好。     

Real-time observation of template-assisted colloidal aggregation and colloidal dispersion under an alternating electric field

A fascinating colloid phenomenon was observed in a specially designed template-assisted cell under an alternating electrical field.Most colloidal particles experienced the processes of aggregation,dispersion and climbing up to the plateaus of the patterns pre-lithographed on the indium tin oxide glass as the frequency of the alternating electrical field increased.Two critical frequencies f crit1 ≈ 15 kHz and f crit2 ≈ 40 kHz,corresponding to the transitions of the colloid behaviour were observed.When f < 15 kHz,the particles were forced to aggregate along the grooves of the negative photoresist patterned template.When 15 kHz < f < 40 kHz,the particle clusters became unstable and most particles started to disperse and were blocked by the fringes of the negative photoresist patterns.As the frequency increased to above 40 kHz,the majority of particles started to climb up to the plateaus of the patterns.Furthermore,the dynamics analysis for the behaviour of the colloids was given and we found out that positive or negative dielectrophoresis force,electrohydrodynamic force,particle-particle interactions and Brownian motion change with the frequency of the alternating electric field.Thus,changes of the related forces affect or control the behaviour of the colloids.