Martin R Scott, Ratzlaff Kenneth L, Huynh Bryan H, Lunte Susan M
Department of Pharmaceutical Chemistry and Center for Bioanalytical Research, The University of Kansas, Lawrence 66047, USA.
Anal Chem. 2002 Mar 1;74(5):1136-43. doi: 10.1021/ac011087p.
A new electrode configuration for microchip capillary electrophoresis (CE) with electrochemical (EC) detection is described. This approach makes it possible to place the working electrode directly in the separation channel. The "in-channel" EC detection was accomplished without the use of a decoupler through the utilization of a specially designed, electrically isolated potentiostat. The effect of the working electrode position on the separation performance (in terms of plate height and peak skew) of poly(dimethylsiloxane)-based microchip CEEC devices was evaluated by comparing the more commonly used end-channel configuration with this new in-channel approach. Using catechol as the test analyte, it was found that in-channel EC detection decreased the total plate height by a factor of 4.6 and lowered the peak skew by a factor of 1.3. A similar trend was observed for the small, inorganic ion nitrite. Furthermore, a fluorescent and electrochemically active amino acid derivative was used to directly compare the separation performance of in-channel EC detection to that of a widely used laser-induced fluorescence (LIF) detection scheme. In this case, it was found that the plate height and peak skew for both detection schemes were essentially equal, and the separation performance of in-channel EC detection is comparable to LIF detection.
本文描述了一种用于具有电化学（EC）检测功能的微芯片毛细管电泳（CE）的新型电极配置。这种方法能够将工作电极直接置于分离通道中。通过使用专门设计的电隔离恒电位仪，无需解耦器即可实现“通道内”EC检测。通过将这种新的通道内方法与更常用的通道末端配置进行比较，评估了工作电极位置对基于聚二甲基硅氧烷的微芯片CE-EC装置分离性能（以塔板高度和峰不对称性衡量）的影响。以儿茶酚作为测试分析物，发现通道内EC检测使总塔板高度降低了4.6倍，峰不对称性降低了1.3倍。对于小的无机离子亚硝酸盐也观察到类似趋势。此外，使用一种荧光且具有电化学活性的氨基酸衍生物，将通道内EC检测的分离性能与广泛使用的激光诱导荧光（LIF）检测方案的分离性能进行直接比较。在这种情况下，发现两种检测方案的塔板高度和峰不对称性基本相等，通道内EC检测的分离性能与LIF检测相当。
