8—氮鸟嘌呤的极谱伏安行为

用循环伏安法（ＣＶ）、电流采样极诸法（ＳＣＰ，即ＴＡＳＴ）、常规脉冲极谱法（ＮＰＰ）、微分脉冲极谱法（ＤＰＰ）、线性扫描伏安法（ＬＳＶ）、Ｏｓｔｅｒｙｏｕｎｇ方波伏安法（ＯＳＷＶ）和计时库仑法（ＣＣ）等电化学技术研究了抗癌药物８－氮鸟嘌呤（８－ａｚａｇｕａｎｉｎｅ，ｇｕａｎａｚｏｌｏ，简称８－ＡＧ）的极谱伏安行为．在 ０． １ｍｏｌ／Ｌ Ｈ２ＳＯ４底液中，８－ＡＧ有一良好的还原峰，峰电位（Ｅｐ）在－０． ９５Ｖ（ｖｓ．Ａｇ／ＡｇＣｌ，下同）附近，８－ＡＧ浓度在４×１０－６～８×１０－４ｍｏｌ／Ｌ范围内．峰高与浓度有良好的线性关系，线性相关系数ｒ＝０．９９９９～０．９９１０，检出限为１× １０－６ｍｏｌ／Ｌ．实验证明了该峰具有吸附性．本文提出了电极反应机理，它包括：酸性介质中８－ＡＧ的质子化、质子化的８－ＡＧ在汞电极上吸附以及完全不可逆的两电子还原过程．同时用量子化学计算方法（全略微分重叠法即ＣＮＤＯ／２）对８－ＡＧ和鸟嘌呤的各原子的净电荷以及Ｗｉｂｅｒｇ键级进行了计算，从理论上解释了８－ＡＧ的电化学还原机理。

The Polarographic and Voltammetric Behaviour of 8 -Azaguanin

Polarographic and voltammetric behaviour of 8-azaguanine, an anticancer drug, has been investigated by cyclic voltammetry, linear sweep voltammetry, sampled current polarography, normal pulse polarography, differential pulse polarography, Osteryoung square wave voltammetry and chronocoulometry. In the base solution of 0. 1 mol/L H2SO4, a welldefined reduction peak of 8-azaguanine was obtained, and the peak potential is-0. 95 V(vs Ag/AgCl). The peak current is directly proportional to the concentration of 8-azaguanine over the range of 4 X 10-6 mol/L-8 X 10-4 mol/L. The detection limit is 1 X 10-6 mol/L, The adsorption characteristic of the peak was proved by the experiments. A mechanism is proposed for the electrode process, which involves the protonation of 8-azaguanine in acidic medium, the adsorption of the protonated 8-azaguanine on the dropping mercury electrode and a totally irreversible two electron reduction of the compound. The electrochemical reduction of 8-azaguanine has also been explained by the calculation results of quantum chemistry on 8-azaguanine and guanine.