尾式吡啶基锰卟啉修饰电极的作用行为及应用

Electrochemical behavior of ascorbic acid anion and Hydroxyl with tailed manganese(Ⅲ)metalloporphyrin and determination of ascorbic acid

用电化学法研究了氯化5-[o-(4-(3-吡啶氧基)丁氧基)苯基]-10,15,20-三苯基锰(Ⅲ)卟啉修饰碳糊电极对抗坏血酸催化作用,以及不同pH下抗坏血酸(H_2A)和OH^-在[PyTPP Mn(Ⅲ)]CI的作用机制．pH2．2～5．2范围内,修饰电极对H_2A为一质子参与的电催化机理;随着pH的增加,OH^-和H_2A在电极上形成电催化氧化竞争,pH＞8．2时,由于OH^-逐渐占据了电活性中心,导致OH^-优先于H_2A在电极上电催化氧化,电化学和UV-Vis光谱证明OH^-与卟啉金属中心强烈作用,形成了氢氧根桥联锰卟啉二聚体结构,该修饰电极在酸性条件(pH4．0左右)用于H_2A的测定,在3．992×10^(-6)～4．602×10^(-4)M浓度范围内线性回归方程为Y=0．1449X+0．05894,R=0．9977(n=11);检测限可达7．067×10^(-7)M,并且电极在常温下保存1月,活性仍然稳定。

This paper reports a novel tailed metalloporphyrin manganese（Ⅲ） 5-o-[4-（3-pyridyloxy） butoxy ] phenyl -10,15,20 -triphenyphorphine chloride （ noted [ PyTPPMn （ Ⅲ） ] Cl ） modified carbon paste electrode. The cyclic vohammograms （ CVs ） show that the [ PyTPPMn（ Ⅲ ） ]Cl modified electrode has an apparent catalysis toward ascorbic acid（H2A）. What＇s the most interesting is that two different electrochemical behaviors toward H2A were observed at different pH occurring on the surface of the prepared carbon paste electrode. Between the pH of 2.2 - 5.2, results show that a proton participates in this electrode reaction. With the increasing of pH, the hydroxyl acts as a competitive opponent to the H2A anion, When pH is more than 8.2, hydroxyl occupied the active center of the porphyrin which lead to that hydroxyl priority to H2A to be oxidized on the surface of the electrode. Both CVs and UV-Vis spectrum further confirm that a strongly interaction takes place between the hydroxyl and metalloporphyrin center, which can be attributed to the formation of a dimeric configuration. Using this modified electrode to detect the H2A solution of different concentration in the range of 3. 992 × 10 ^-6 - 4.602 × 10 ^-4 M, an excellent linearity is observed and the relative coefficient is 0. 9977. The detection limitation for H2A is 7. 067 × 10^ -7 M. Keeping this modified electrode at normal temperature for about one month, no significant change has been observed.