State Key Laboratory Base of Eco-chemical Engineering, College of Chemistry and Molecular Engineering, Qingdao University of Science and Technology, Qingdao, PR China.
Anal Chem. 2011 Feb 15;83(4):1291-9. doi: 10.1021/ac102344y. Epub 2011 Jan 19.
A novel integrated concentration/separation approach involving online combination of sweeping with electrokinetic injection and analyte focusing by micelle collapse (AFMC) with heart-cutting two-dimensional (2D) capillary electrophoresis (CE) in a single capillary was developed for analysis of Herba Leonuri and mouse blood samples. First, a new sweeping with an electrokinetic injection preconcentration method was developed to inject a large volume sample solution and significantly enhance detection sensitivity. Then, the preconcentration scheme was integrated to the 2D-CE to provide significant analyte concentration and extremely high resolving power. The sample was preconcentrated by sweeping with electrokinetic injection and separated in first dimension micellar electrokinetic chromatography (MEKC). Then, only a desirable fraction of the first dimension separation was transferred into the second dimension of the capillary by pressure and further analyzed by capillary zone electrophoresis (CZE) acting as the second dimension. As the key to successful integration of MEKC and CZE, an AFMC step was integrated between the two dimensions to release analytes from the micelle interior to a liquid zone and to overcome the sample zone diffusion caused by mobilization pressure. The injected sample plug lengths for flavonoids under 15 kV for 60 min were experimentally estimated as 546 cm. The dual concentration methods resulted in the increased detection factors of 6000-fold relative to the traditional pressure injection method. The relative standard deviation (RSD) values of peak height, peak area, and migration time were 2.7-4.5%, 1.9-4.3%, and 4.7-6.8% (n = 10), respectively. The limits of detection (S/N = 3) were in the range of 7.3-36.4 ng/L, and the theoretical plate numbers (N) were in the range of 1.7-4.3 × 10(4) plates/m. This method has been successfully applied to determine flavonoids in Herba Leonuri and postdosing mouse blood samples. The pharmacokinetic study also demonstrated that the proposed concentration/separation method was convenient and sensitive and would become an attractively alternative method for online sample concentration and separation in complex samples.
一种新型的一体化浓缩/分离方法，涉及在线结合胶束电动进样的扫集与胶束相坍塌导致的分析物聚焦（AFMC），并在单根毛细管内通过二维（2D）毛细管电泳（CE）进行心切割，用于分析益母草和小鼠血样。首先，开发了一种新的电动力学进样扫集预浓缩方法，以注入大体积的样品溶液并显著提高检测灵敏度。然后，将预浓缩方案集成到 2D-CE 中，提供显著的分析物浓缩和极高的分辨率。样品通过电动力学进样的扫集进行预浓缩，并在第一维胶束电动色谱（MEKC）中分离。然后，仅通过压力将第一维分离的一个期望部分转移到毛细管的第二维中，并通过作为第二维的毛细管区带电泳（CZE）进一步分析。作为成功整合 MEKC 和 CZE 的关键，在二维之间集成了一个 AFMC 步骤，以将分析物从胶束内部释放到液体区域，并克服由迁移压力引起的样品区扩散。在 15 kV 下，实验估计黄酮类化合物的注入样品塞长度为 546 cm，持续 60 分钟。与传统的压力进样方法相比，双重浓度方法导致检测因子增加了 6000 倍。峰高、峰面积和迁移时间的相对标准偏差（RSD）值分别为 2.7-4.5%、1.9-4.3%和 4.7-6.8%（n = 10）。检测限（S/N = 3）的范围为 7.3-36.4 ng/L，理论板数（N）的范围为 1.7-4.3 × 10(4) 板/m。该方法已成功应用于测定益母草中黄酮类化合物和给药后小鼠血样中的含量。药代动力学研究还表明，所提出的浓缩/分离方法方便、灵敏，将成为复杂样品中在线样品浓缩和分离的一种有吸引力的替代方法。
