Berduque Alfonso, Zazpe Raúl, Arrigan Damien W M
Tyndall National Institute, Lee Maltings, University College, Cork, Ireland.
Anal Chim Acta. 2008 Mar 24;611(2):156-62. doi: 10.1016/j.aca.2008.01.077. Epub 2008 Feb 8.
The detection of protonated dopamine by differential pulse voltammetry (DPV) and square wave voltammetry (SWV) at arrays of micro-interfaces between two immiscible electrolyte solutions (microITIES) is presented. Microfabricated porous silicon membranes (consisting of eight pores, 26.6 microm in radius and 500 microm pore-pore separation, in a hexagonal layout) were prepared by photolithographic and etching procedures. The membrane pores were fabricated with hydrophobic internal walls so that the organic phase filled the pores and created the liquid interface at the aqueous side of the membrane. These were used for harnessing the benefits of three-dimensional diffusion to the interface and for interface stabilisation. The liquid-liquid interface provides a simple method to overcome the major problem in the voltammetric detection of dopamine at solid electrodes due to the co-existence of ascorbate at higher concentrations. Selectivity for dopamine over ascorbate was achieved by the use of dibenzo-18-crown-6 (DB18C6) for the facilitated ion transfer of dopamine across the microITIES array. Under these conditions, the presence of ascorbate in excess did not interfere in the detection of dopamine and the lowest concentration detectable was ca. 0.5 microM. In addition, the drawback of current signal saturation (non-linear increase of the peak current with the concentration of dopamine) observed at conventional (millimetre-sized) liquid-liquid interfaces was overcome using the microfabricated porous membranes.
本文介绍了通过差分脉冲伏安法（DPV）和方波伏安法（SWV）在两种不混溶电解质溶液之间的微界面阵列（微ITIES）上检测质子化多巴胺的方法。通过光刻和蚀刻工艺制备了微加工多孔硅膜（呈六边形布局，由八个半径为26.6微米、孔间距为500微米的孔组成）。膜孔的内壁具有疏水性，使得有机相填充孔并在膜的水相一侧形成液体界面。这些用于利用三维扩散到界面的优势以及界面稳定化。液 - 液界面提供了一种简单的方法来克服在固体电极上伏安检测多巴胺时由于高浓度抗坏血酸盐共存而产生的主要问题。通过使用二苯并 - 18 - 冠 - 6（DB18C6）促进多巴胺跨微ITIES阵列的离子转移，实现了对多巴胺相对于抗坏血酸盐的选择性。在这些条件下，过量抗坏血酸盐的存在不会干扰多巴胺的检测，可检测的最低浓度约为0.5微摩尔。此外，使用微加工多孔膜克服了在传统（毫米尺寸）液 - 液界面观察到的当前信号饱和（峰电流随多巴胺浓度非线性增加）的缺点。
