Kitagawa Fumihiko, Wakagi Shinichiro, Takegawa Yuuki, Nukatsuka Isoshi
Department of Frontier Materials Chemistry, Graduate School of Science and Technology, Hirosaki University.
Anal Sci. 2019 Aug 10;35(8):889-893. doi: 10.2116/analsci.19P106. Epub 2019 Apr 19.
To achieve highly sensitive analysis without labor-intensive experimental procedures in capillary electrophoresis (CE), large-volume sample stacking with an electroosmotic flow pump (LVSEP)-field-amplified sample injection (FASI) was combined with a dynamic coating technique. In this study, poly(vinyl pyrrolidone) (PVP) was employed for the dynamic coating additive. Since a standard fluorescent dye, fluorescein, was well concentrated in a conventional LVSEP, the PVP dynamically-coated capillaries can be also applied to the LVSEP-FASI analysis. In our home-made CE apparatus, however, current breakdown was often caused, especially at a longer electrokinetic injection time due to bubble formation. To avoid the interference of bubble formation, the distance between the tips of the electrode and the capillary in the vertical direction was changed from 0 to 2.5 cm under the magnetic stirring condition. This allowed for a long electrokinetic injection time of up to 20 min, resulting in a sensitive enhancement factor (SEF) of 34900 for fluorescein. The developed method was applied to the chiral analysis of amino acids in CE. As a result, leucine (Leu) was successfully separated in LVSEP-FASI with SEFs of 6420 and 4500 for the D- and L-Leu peaks, respectively.
为了在毛细管电泳（CE）中无需繁琐的实验步骤即可实现高灵敏度分析，将使用电渗流泵的大体积样品堆积（LVSEP）-场放大进样（FASI）与动态涂层技术相结合。在本研究中，聚（乙烯基吡咯烷酮）（PVP）被用作动态涂层添加剂。由于标准荧光染料荧光素在传统的LVSEP中能很好地富集，因此PVP动态涂层毛细管也可应用于LVSEP-FASI分析。然而，在我们自制的CE仪器中，经常会出现电流中断的情况，尤其是在较长的电动进样时间时，这是由于气泡形成所致。为了避免气泡形成的干扰，在磁力搅拌条件下，将电极尖端与毛细管在垂直方向上的距离从0改变为2.5 cm。这使得电动进样时间长达20分钟，荧光素的灵敏增强因子（SEF）达到34900。所开发的方法应用于CE中氨基酸的手性分析。结果，亮氨酸（Leu）在LVSEP-FASI中成功分离，D-亮氨酸和L-亮氨酸峰的SEF分别为6420和4500。
