L-半胱氨酸自组装膜电极对米吐尔的电催化及其分析应用

Electrocatalysis of Metol at L-Cysteine Self-assembled Monolayers Modified Gold Electrode and Its Application

研究了米吐尔在L 半胱氨酸自组装膜修饰金电极上的电化学行为。米吐尔在该修饰电极上的CV曲线仅出现一对峰 ,其峰形对称 ,ΔEp =42mV ,氧化还原峰电流之比约等于 1,为可逆反应 ;扩散系数D =2 .2 4× 10 - 6 cm2 ·s- 1 。初步探讨了电催化机理。差分脉冲伏安法测定其氧化峰电流与米吐尔浓度在 5 .0× 10 - 7～ 2 .0× 10 - 5mol/L和 5 .0× 10 - 5～ 1.0× 10 - 3 mol/L范围内分段呈线性关系 ;相关系数分别为 0 .9987和 0 .9972 ;检测限 1.0× 10 -

The electrochemical behavior of metol at the L-cysteine self-assembled monolayer modified gold electrode has been studied. The experimental results show that the DeltaE(p) is 42 mV, the shape of peaks is symmetric and the ratio of anodic and cathodic peak currents is about I, which suggests that the electrode process is reversible one. The oxidation peak potential shifts negatively about 132 mV. Diffusion coefficient is 2.24 x 10(-6) cm(2) . s(-1). The electrocatalytical mechanism has been discussed. There are two excellent linearity between oxidation peak current and concentration of metol in the range of 5.0 x 10(-7) similar to 2.0 x 10(-5) mol/L (r = 0.9987) and 5.0 x 10(-5) similar to 1.0 x 10(-3) mol/L (r = 0.9972) by differential pulse voltammetric method. Detection limit is down to 1.0 x 10(-8) mol/L. Some ordinary ions do not interfere with the determination of metol. Relative standard deviations of the oxidation peak currents obtain from 10 determinations of the same solutions containing 2.0 x 10(-6) and 2.0 x 10(-4) mol/L metol are 4.4% and 2.5% respectively. This method has been applied to the determination of metol in photographic imaging agents successfully.