层层自组装纳米金/硫堇修饰玻碳电极测定亚硝酸根

研究了纳米金/硫堇多层膜修饰玻碳电极的制备以及亚硝酸根在该电极上的电化学行为。在稀硝酸溶液中，通过恒电位法将玻碳电极活化，使其表面产生-COH等含氧基，然后将其浸泡在硫堇溶液中，硫堇中的-NH2与玻碳电极表面的-COH基团发生席夫碱反应，将硫堇固定在电极上。最后将电极浸泡在纳米金溶液中，通过纳米金与硫堇的相互作用将纳米金修饰到电极表面，从而制得纳米金/硫堇多层膜修饰玻碳电极。实验结果表明，该修饰电极能显著促进亚硝酸根在电极表面的电化学过程，电化学响应信号与亚硝酸根的浓度在20×10-6~50×10-5 mol/L和50×10-5~20×10-3 mol/L范围内呈良好的线性关系，检出限为5×10-8 mol/L (S/N=3)。方法用于水样中亚硝酸根的测定，相对标准偏差为22%~32%，回收率在98%~104%范围。

Determination of nitrite by layer-by-layer self-assembly nano-gold/ thionine modified glassy carbon electrode

The preparation of nano-gold / thionine multilayer film modified glassy carbon electrode and the electrochemical behavior of nitrite on this electrode were studied.The glassy carbon electrode was activated by potentiostatic method in dilute nitric acid solution to generate oxygen-bearing groups(such as-COH) on electrode surface.Then,the electrode was immersed in thionine solution.The schiff alkali reaction occurred between-NH2 in thionine with-COH on glassy carbon electrode surface to immobilize of thionine on electrode.Finally,the nano-gold was modified on the surface of the electrode immersed in a nano-gold solution by interreaction of nano-gold with thionine,realizing the preparation of nano-gold / thionine multilayer film modified glassy carbon electrode.The experimental results showed that,this modified electrode could significantly accelerate the electrochemical process of nitrite on electrode surface.The electrochemical response signal was linear to the concentration of nitrite in range of 2×10-6-5.0×10-5 mol/L and 5.0×10-5-2.0×10-3 mol/L.The detection limit of nitrite was 5×10-8 mol/ L(S/N=3).The proposed method was applied to the determination of nitrite in water samples with relative standard deviations of 2.2%-3.2% and recoveries of 98%-104%.