Accumulation Voltammetry for 17β-Estradiol Using Hydrophobic Cationic Surfactant and Glassy Carbon Electrode Modified with Multi-Walled Carbon Nanotube Dispersed Nafion Membrane(<Special Article>The First Papers of Prospective Analytical Chemists)

多層カーボンナノチューブ(MWCNT)を分散させたNafion溶液をスピンコーティング法によりグラッシーカーボン(GC)表面に薄膜として修飾させた電極を用い,疎水性の高い陽イオン界面活性剤(ゼフィラミン,塩化ベンゼトニウム,臭化セチルトリメチルアンモニウム)共存下における17β-エストラジオール(E2)の電気化学的応答を調査した.Nafion膜を修飾したGC電極を用いた場合,E2の電気化学的酸化応答は支持電解質溶液に陽イオン界面活性剤を添加することにより大きく増加した.更に, MWCNTを分散させたNafion膜修飾GC電極では,Nafion膜修飾GC電極と比較して,約2.5倍高いE2の酸化応答が得られた.本研究で用いた陽イオン界面活性剤によるE2の電流応答増大効果は,ゼフイラミンで最も高く得られることが示された.この現象を利用し,濃縮ボルタンメトリーによるE2の簡便・高感度定量を試みた結果,定量範囲は5×10^〜1×10^M,検出限界は6×10^であった.\nA simple and sensitive voltammetric method for detecting 17β-estradiol (E2) was developed. The Nafion membrane dispersed multi-walled carbon nanotube (MWCNT) modified electrode was prepared by spin-coating a 1.5 wt% Nafion ethanolic solution including 2 mg/mL MWCNT on glassy carbon (GC) at 2400 rpm. The voltammetric behavior of E2 was investigated with linear sweep voltammetry in an electrolyte including a hydrophobic cationic surfactant, such as Zephiramine, benzethonium chloride (BTC) , and cethyltrimethylammonium bromide (CTAB). The peak current for the oxidation of E2 at the MWCNT-Nafion-GC electrode was enhanced by the presence of each hydrophobic cationic surfactant. The enhancement effect by Zephiramine was strongestwhen compared to the others. Although E2 belowa concentration of 1×10^M at a bare GC electrode can not be measured, the peak current for the oxidation of 1×10^M E2 could be observed by using the MWCNT-Nafion-GC electrode in the presence of 6×10^M Zephiramine