嘌呤的电化学还原及其形式电位E^0~'的计算

Study on Electrochemical Reduction of Purine and the Calculation of Its Formal Potential E 0'

通过正交设计，选择最佳条件，使嘌呤的电极过程变为准可逆过程，利用简单准可逆过程的脉冲极谱理论，通过图解法，获得嘌呤的表观动力学参数．嘌呤二个峰的电子传递系数ａ分别为０．０８和０．１４，标准异相速度常数ｋｓ分别为３．５×１０－３ｃｍ／ｓ和２．２×１０－３ｃｍ／ｓ．结合循环伏安法，计算出嘌呤相应峰的形式电位Ｅ０＇分别为－１．１６Ｖ（ＶＳ．ＳＣＥ）和－１．３０Ｖ（ＶＳ．ＳＣＥ）．研究结果表明，Ｅ０＇与嘌呤浓度无关。

The guasi-reversible behavior of purine is shown in the best experimental condition by orthogonal method.The apparent kinetic for the electrochemical reduction of purine are obtained using a graphic method based on theory for a quasi-reversible electrode process and by pulse polarogaphy .The transfer coefficients of two peaks of purine are 0.08(a)and 0.14 (a 2).The standard heteogeneous rate constants are 3.5×1 -3 cm/s(ks 2).and 2.2×10 -3 cm/s(ks 2).These parameters are used to calculate the formal potentialE 0' with reference to cyclic voltammetry measurements.The formal potentals are -1.16V(E 0' 1)and -1.30V(E 0' 2)(VS.SCE).The results show that E 0' is not related to the concentration of purine but is related to pH.