Department of Chemistry, Shantou University, Shantou, Guangdong 515063, China.
J Chromatogr A. 2011 Aug 19;1218(33):5712-7. doi: 10.1016/j.chroma.2011.06.074. Epub 2011 Jun 26.
A novel method of on-line single drop microextraction (SDME) coupled with sweeping micellar electrokinetic chromatography (MEKC) for the selective extraction and dual preconcentration of alkaloids was developed. In this technique, analytes of three alkaloids were firstly extracted from 4.0 mL basic aqueous sample solution (donor phase, 500 mM NaOH) into a layer of n-octanol at temperature 30 °C with the stirring rate of 1150 rpm, then back-extracted into the acidified aqueous acceptor (acceptor phase, 50 mM H₃PO₄) suspended at the tip of a capillary at 650 rpm. Then, the aqueous acceptor was introduced into capillary by hydrodynamic injection with a height difference of 15 cm between the inlet and outlet of capillary for 300 s, and analyzed directly by on-line sweeping MEKC. With the selective SDME, we were able to extract three alkaloids without any interfering components in human urine samples. Under the optimum conditions, the proposed method achieved limits of detections (LOD) of between 0.2 ng mL⁻¹ and 1.5 ng mL⁻¹ with 1583-3556-fold increases in detection sensitivity for three analytes, which indicated that it was a promising method for analysis of alkaloids in human urine.
一种新颖的在线单滴微萃取（SDME）与胶束电动色谱（MEKC）联用的方法被开发出来，用于选择性萃取和双重预浓缩生物碱。在该技术中，三种生物碱的分析物首先从 4.0 毫升碱性水性样品溶液（供体相，500 mM NaOH）中在 30°C 的温度下用 1150 rpm 的搅拌速度萃取到一层正辛醇中，然后用酸化的水性接受相（接受相，50 mM H₃PO₄）反萃取到在 650 rpm 下悬浮在毛细管尖端的接受相中。然后，通过在毛细管入口和出口之间存在 15 厘米高度差的水力注射将水性接受相引入毛细管中，持续 300 秒，并通过在线扫集 MEKC 直接分析。通过选择性 SDME，我们能够在人尿样中提取出没有任何干扰成分的三种生物碱。在最佳条件下，该方法对三种分析物的检测限（LOD）在 0.2 ng mL⁻¹ 到 1.5 ng mL⁻¹ 之间，检测灵敏度提高了 1583-3556 倍，这表明它是一种有前途的分析人尿中生物碱的方法。
