Prepartion of Poly(diallyldimethylammonium chloride) Film Modified Electrodes for Bisphenol A Determination

[[abstract]]本研究利用一個簡單且快速的方法，將電極經過活化處理後，將陽離子型聚電解質聚(二烯丙基二甲基氯化銨)( poly(diallyldimethylammonium chloride), PDDA)滴至電極表面，放置一天便可成功製備聚(二烯丙基二甲基氯化銨)修飾電極(SPCE*/PDDA)。 在電化學分析的應用上，我們使用不同以往的方法，先將SPCE*/PDDA浸泡至雙酚A溶液中，一段時間後將電極取出，用二次水簡單沖洗電極表面後，放入空白溶液用循環伏安法掃描，發現有雙酚A氧化訊號，與bare SPCE相比，修飾電極吸附雙酚A得到的氧化電流值增加了10倍，推測是因為電極表面上的PDDA帶正電荷，利用靜電作用力的方式將雙酚A吸引至電極表面。 我們改變BPA溶液的pH值，觀察吸附的變化，發現在pH9的水溶液下吸附所得到的氧化電流值最大，由於雙酚A在pH9的環境下解離帶負電，大大增加了吸附至電極的量，造成電流值上升。進一步的利用差式脈衝伏安法(Differential Pluse Voltammetry, DPV)進行定量分析，靈敏度為11.239 µA/µM，線性範圍為0.25 µM-25 µM，偵測極限為0.045 µM (S/N=3)。[[abstract]]In this study, we modified a thin layer of poly(diallyldimethylammonium chloride) on SPCE (screen-printed carbon electrode) by a simple and fast method which just need two steps. First is to activate SPCE. Secondly, drop poly(diallyldimethylammonium chloride) onto SPCE*, and dry in the air overnight. In this way, the modified electrode was examined as electrochemical sensors for bisphenol A (BPA). Unlike the usual ways on BPA determination, the modified electrode was immersed in BPA solution for 20 minutes, then transferred to a blank solution for CV scanning. We observed a oxidation peak at +0.6 V. Compared with bare SPCE, the oxidation current of BPA on SPCE*/PDDA was 10 times as much as bare SPCE’s. According to this result, we presumed that positively charged PDDA on the electrode surface caused bisphenol A adsorbed on the electrode surface by electrostatic attraction. Moreover, we changed the pH value of BPA solution and observed the variation of oxidation current, which could find that the current in pH9 medium is the largest. We further used differential pluse voltammetry, an analytical method, for BPA determination. The fabricated sensor showed linear response to BPA in the ranges of 0.25–25 µM, and the sensitivity was 11.239 µA/µM. The detection limit was 0.045 µM (S/N=3).[[note]]碩