Department of Chemistry, University of Basel, Basel, Switzerland.
Anal Chim Acta. 2013 Jul 17;787:254-9. doi: 10.1016/j.aca.2013.05.039. Epub 2013 Jun 3.
The common sweeteners aspartame, cyclamate, saccharin and acesulfame K were determined by capillary electrophoresis with contactless conductivity detection. In order to obtain the best compromise between separation efficiency and analysis time hydrodynamic pumping was imposed during the electrophoresis run employing a sequential injection manifold based on a syringe pump. Band broadening was avoided by using capillaries of a narrow 10 μm internal diameter. The analyses were carried out in an aqueous running buffer consisting of 150 mM 2-(cyclohexylamino)ethanesulfonic acid and 400 mM tris(hydroxymethyl)aminomethane at pH 9.1 in order to render all analytes in the fully deprotonated anionic form. The use of surface modification to eliminate or reverse the electroosmotic flow was not necessary due to the superimposed bulk flow. The use of hydrodynamic pumping allowed easy optimization, either for fast separations (80s) or low detection limits (6.5 μmol L(-1), 5.0 μmol L(-1), 4.0 μmol L(-1) and 3.8 μmol L(-1) for aspartame, cyclamate, saccharin and acesulfame K respectively, at a separation time of 190 s). The conditions for fast separations not only led to higher limits of detection but also to a narrower dynamic range. However, the settings can be changed readily between separations if needed. The four compounds were determined successfully in food samples.
采用毛细管电泳-非接触电导检测法对常见甜味剂阿斯巴甜、环己烷氨基磺酸钠、糖精和安赛蜜进行了测定。为了在电泳运行过程中获得最佳的分离效率和分析时间之间的折衷，采用基于注射泵的顺序注射阀，在电泳过程中施加了流体动力学泵。通过使用内径为 10μm 的狭窄毛细管，避免了峰展宽。分析在 pH 值为 9.1 的 150 mM 2-(环己基氨基)乙磺酸和 400 mM 三羟甲基氨基甲烷的水溶液运行缓冲液中进行，以使所有分析物都处于完全去质子化的阴离子形式。由于叠加的体流，无需使用表面修饰来消除或反转电渗流。由于使用了流体动力学泵，因此可以轻松优化，无论是快速分离（80s）还是低检测限（6.5μmol L(-1)、5.0μmol L(-1)、4.0μmol L(-1)和 3.8μmol L(-1)，分离时间为 190s）都可以。快速分离的条件不仅导致检测限更高，而且动态范围更窄。但是，如果需要，在分离之间可以轻松更改设置。成功地在食品样品中测定了这四种化合物。
