可裝卸式微晶片電泳結合碳墨電化學偵測器之研究

Abstract

目前微型全分析系統發展迅速，其中微晶片電泳受到相當的注目，近來發展出成本便宜且製作簡單的高分子微晶片，而電化學偵測法具高靈敏度、選擇性好和微小可攜帶式的特性，有很好的偵測效能，愈來愈常和微晶片電泳結合進行偵測。 本實驗利用灌注成型的方式製作聚二甲基矽氧烷(poly(dimethyl -siloxane)，PDMS)微流道，並於玻璃上製造阻斷器(decoupler)和碳工作電極，再利用聚甲基丙烯酸甲酯(poly(methylmethacrylate)，PMMA)夾具將其組裝成可拆式重複使用型的電化學微晶片系統，因為使用off-channel偵測模式，阻斷器和工作電極都擺置在微流道內，因此改進碳工作電極和微流道間的密合程度，最後利用稀釋碳墨的方式，將碳工作電極的厚度降低，得到密封度良好的組裝，以兒茶酚和多巴胺進行效能測試，在分離電場變化、注射長度、樣品濃度、夾具穩定度方面都有良好的性能表現。 最後將所發展的可裝卸式電化學微晶片系統應用於酚酸偵測，在5分鐘內得到綠原酸、芥子酸、咖啡酸和香草酸的訊號，理論板數為22600 ~ 30800 (N/cm)，解析度有1.05以上，偵測極限為0.23(綠原酸) ~ 1.41(香草酸) □M，並選用咖啡為真實樣品進行偵測，有相當良好的應用效果。

Micro total analysis systems were developed rapidly and got great attention, especially low cost and easy fabrication of polymer microchip. In recent years, electrochemical detection was increasing utilized with the capillary electro- phoresis microchip (MCE). It offers the advantages, including high sensitivity, good selectivity, miniaturization of detector and instrument, and great performance. We developed a microchip device combined with MCE and carbon ink electrochemical detector. The microchannels were made by molding poly- (dimethylsiloxane) (PDMS) from a patterned silica wafer. The PDMS slab was then sealed to the glass substrate with palladium film (as decoupler) and carbon ink electrode (as working electrode). The integrated microchip device was reversibly fastened with laboratory-build poly(methylmethacrylate) (PMMA) holder. Utilized off-channel detection mode which placed carbon working electrode and decoupler within the microchannel. We diluted carbon ink to get thinner carbon electrode for improving the sealed ability of microchip. Dopamine and catechol are used to show the performance of microchip about separation voltage, injection length, sample concentration, and stability. By using the MCE method coupled with amperometric detection, we can rapidly and successfully detect four phenolic acids, chlorogenic acid, sinapic acid, caffeic acid and vanillic acid in 5 min. Theoretical plates are in range of 22600 ~ 30800 (N/cm) and resolutions are above 1.05. Detection limits are from 0.23 □M for chlorogenic acid to 1.41 □M for vanillic acid. The applicability of this system to the real sample, coffee, was demonstrated well.