本實驗室先前所開發的電化學安培法-毛細管電泳晶片(CE Chip)，非但所需設備可簡便化，而且對Dopamine之偵測靈敏度至少已可達0.1 M程度。其偵測原理乃藉由樣本被從注入毛細管中到EOF下的分離，於工作電極上發生氧化還原反應，而產生電子轉移所得到電流之響應。基本上，受測樣本必須是具氧化還原活性之物質。然如K+、Ca2+及Li+等無機離子皆非此類之物質，無法以安培法直接量測，故本研究欲發展導電度量測法，以互補僅有安培法下偵測需要上的不足。本研究的導電度式CE晶片，乃以微機電製程經顯影蝕刻，製作出對極式（寬度、間距各為50與30 m）之微小金電極，再以PDMS灌模獲得寬、高各為150與13 m之微管道，透過O2 plasma處理後接合即完成晶片之製備。實驗所偵測之對象，在有機物方面有Catechol、Dopamine、Histamine、Vitamin C等，而無機離子以K+、Li+、Ca2+等為主，此外也針對Hg2+、Zn2+、Pb2+、Ag+、Cu2+等重金屬離子進行檢測。研究過程分為個別偵測與混合偵測二種階段：於個別偵測時以440 V/cm先行30 sec之注入，再以230 V/cm之電場進行樣本分離。由結果可發現所有待測物除Catechol以外，其餘皆可於90 sec內被量測，然而於偵測極限上各不相同，如Li+之極限值僅達50 mM而Hg2+則可降低至25 M (5 ppm)，此結果可能為個別離子本身導電性差異所致；於混合偵測方面以80 V/cm進行3~5 sec之注入，分離電場則為200 ~ 230 V/cm，於結果顯示混合陽離子分離之效能雖不理想，但於陰陽離子之混合(Na+及CH3COO-)分離已可達成明顯的分離效果。本導電度式CE系統，已可對帶電性之有機及無機物質進行初步偵測，未來若加以改良將可實際應用於真實樣本之量測。

　Conductivity detection can be considered electrochemical technique as well but has the ability to detect any analyte irrespective of whether it contains an electroactive species or not. We used MEMS (Micro electromechanical system) to fabricate the microelectrode, and its specification of width and interval are 50 m and 30 m individually. The microchannel was obtained by cast. After fabricating the mold, PDMS (polydimethylsiloxane) was poured into the cast and cured a period of time. Then peeled PDMS replica from mold and the microchannel was completed. It was 13 m in width and 150 m in depth. In the CE experiment, we detected organic components such as catechol, dopamine, histamine and vitamin C, and inorganic ions like K+, Li+ and Ca2+. The application of heavy metals, including Hg2+, Zn2+, Pb2+, Ag+ and Cu2+, was also investigated. 30 sec electrokinetic injection time for individual sample detection was performed using a field strength (E) of 440 V/cm, and E = 230 V/cm for electrophoresis. Each sample can be detected less than 90 sec excluding catechol. Limitation of detection (LOD) is different from each other. The lowest LOD is 25 M (5 ppm) for Hg2+. On the other hand, the electrophoresis conditions of mixed analytes were 80 V/cm injection for 3 ~ 5 sec, and 200 to 230 V/cm separation. In the results, the separation efficiency of mixed cations are not clear enough to distinguish one peak from another, but it is a good separation for simultaneous measurement of Na+ and CH3COO-. In this study, we have developed the conductivity detection in capillary electrophoresis system.

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