长链四烷基锡作中性载体的亚硝酸根选择性电极的研究

用亲脂的长链四烷基锡作中性载体制备亚硝酸根选择性电极. 其选择性模式与经典的阴离子交换剂相比有显著不同, 相对硝酸根的电位选择性系数改善约4个数量级. 线性响应区间为1x10^-^1-2x10^-^5mol.dm^-^3, 检测下限为5x10^-^6mol.dm^-^3. 电极斜率在弱性介质中为Nernst响应, 在弱酸性介质中为两倍Nernst响应. 紫外光谱研究发现酸度影响载体与阴离子的多级配位平衡. 电极斜率的变化与此平衡密切相关, 在此基础上给出了对电极斜率的异常变化及电位-pH

Long-chain tetraalkyltin compounds as neutral carriers for nitrite-selective PVC membrane electrode

Lipophilic long-chain tetraalkyltin compounds as neutral carriers for nitrite-selective PVC membrane electrodes show selectivity patterns radically different from those obtained with classical anion-exchangers. The potentiometric selectivity coefficient for NO2- with respect to NO3- was improved by ~4 orders of magnitude. The linear response range of the electrode based on tetralauryltin (TLT) is from 0.1 mol/dm3 down to 2 ?10-5 mol/dm3 with a detection limit of 5 ?10-6 mol/dm3. The Nernstian response of the electrode in medium of pH ? gradually changes to a double super-Nernstian response when the solution turns slightly acidic. The change of the response slope has a close relation with the stepwise complex formation equilibrium of the carrier with the anion involved, which was experimental studied with UV spectroscopy. An explanation of the anomalous response behavior as well as the curve form of the mV-pH plot is given.