Meneses Diogenes, Gunasekara Dulan B, Pichetsurnthorn Pann, da Silva José A F, de Abreu Fabiane C, Lunte Susan M
Ralph N. Adams Institute for Bioanalytical Chemistry, University of Kansas, Lawrence, KS, USA; Institute of Chemistry and Biotechnology, Federal University of Alagoas, UFAL, Maceió, AL, Brazil.
Electrophoresis. 2015 Feb;36(3):441-8. doi: 10.1002/elps.201400297. Epub 2014 Nov 14.
In-channel amperometric detection combined with dual-channel microchip electrophoresis is evaluated using a two-electrode isolated potentiostat for reverse polarity separations. The device consists of two separate channels with the working and reference electrodes placed at identical positions relative to the end of the channel, enabling noise subtraction. In previous reports of this configuration, normal polarity and a three-electrode detection system were used. In the two-electrode detection system described here, the electrode in the reference channel acts as both the counter and reference. The effect of electrode placement in the channels on noise and detector response was investigated using nitrite, tyrosine, and hydrogen peroxide as model compounds. The effects of electrode material and size and type of reference electrode on noise and the potential shift of hydrodynamic voltammograms for the model compounds were determined. In addition, the performance of two- and three-electrode configurations using Pt and Ag/AgCl reference electrodes was compared. Although the signal was attenuated with the Pt reference, the noise was also significantly reduced. It was found that lower LOD were obtained for all three compounds with the dual-channel configuration compared to single-channel, in-channel detection. The dual-channel method was then used for the detection of nitrite in a dermal microdialysis sample obtained from a sheep following nitroglycerin administration.
使用两电极隔离恒电位仪进行反向极性分离，对通道内安培检测与双通道微芯片电泳相结合的方法进行了评估。该装置由两个独立的通道组成，工作电极和参比电极相对于通道末端放置在相同位置，从而能够进行噪声扣除。在以往关于这种配置的报告中，使用的是正常极性和三电极检测系统。在此描述的两电极检测系统中，参比通道中的电极同时充当对电极和参比电极。使用亚硝酸盐、酪氨酸和过氧化氢作为模型化合物，研究了通道中电极位置对噪声和检测器响应的影响。确定了电极材料、尺寸以及参比电极类型对模型化合物的噪声和流体动力伏安图电位偏移的影响。此外，还比较了使用铂和银/氯化银参比电极的两电极和三电极配置的性能。尽管使用铂参比电极时信号会衰减，但噪声也显著降低。结果发现，与单通道、通道内检测相比，双通道配置对所有三种化合物的检测限都更低。然后，使用双通道方法对从给予硝酸甘油后的绵羊获得的皮肤微透析样品中的亚硝酸盐进行检测。
