Institute of Materia Medica, Shandong Academy of Medical Sciences, Jinan 250062, P. R. China.
Analyst. 2011 Nov 7;136(21):4486-91. doi: 10.1039/c1an15277g. Epub 2011 Sep 22.
On-line concentration via Electrokinetic Supercharging (EKS) was used to enhance the sensitivity of the capillary electrophoretic separation of the four flavonoids naringenin, hesperetin, naringin and hesperidin. Separation conditions, including the background electrolyte pH and concentration, the length and choice of terminator and the electrokinetic injection time were optimized. The optimum conditions were: a background electrolyte of 30 mM sodium tetraborate (pH 9.5) containing 5% (v/v) of methanol, electrokinetic injection of the sample (130 s, -10 kV) followed by hydrodynamic injecting of 100 mM 2-(cyclohexylamino)ethanesulfonic acid (CHES) (17 s, 0.5 psi) as terminator, and separation with -20 kV. Under these conditions the four flavonoids could be separated with a sample-to-sample time of 15 min and detection limits from 2.0 to 6.8 ng mL(-1). When compared to a conventional hydrodynamic injection the sensitivity was enhanced between 824 and 1515 times which is 7.6-16 times higher than other CE methods for the on-line concentration of flavonoids. The applicability of the developed method was demonstrated by the detection of the four flavonoids in an aqueous extract of Clematis hexapetala pall.
采用电动超浓缩（EKS）在线浓缩技术增强了毛细管电泳分离四种黄酮类化合物（柚皮素、橙皮素、柚皮苷和橙皮苷）的灵敏度。优化了分离条件，包括背景电解质 pH 值和浓度、端基的长度和选择以及电动进样时间。最佳条件为：30 mM 硼酸钠（pH 9.5）中含有 5%（v/v）甲醇的背景电解质，样品电动进样（130 s，-10 kV），然后以 100 mM 2-（环己基氨基）乙磺酸（CHES）（17 s，0.5 psi）作为端基进行水力进样，分离电压为-20 kV。在此条件下，四种黄酮类化合物的分离时间为 15 min，检测限为 2.0-6.8 ng mL(-1)。与传统的水力进样相比，灵敏度提高了 824-1515 倍，比其他用于黄酮类化合物在线浓缩的 CE 方法高 7.6-16 倍。该方法的适用性通过检测Clematis hexapetala pall 水提物中的四种黄酮类化合物得到了证明。
