Bonakdar M, Yu J, Mottola H A
Department of Chemistry, Oklahoma State University, Stillwater, OK 74078-0447, U.S.A.
Talanta. 1989 Jan-Feb;36(1-2):219-25. doi: 10.1016/0039-9140(89)80099-2.
The amperometric performance of two types of chemically modified carbon electrodes developed for the determination of oxides of nitrogen in continuous-flow systems is presented. The modification consists in immobilization of reversible Fe(II)/Fe(III) centers. The first type of electrode is a simple modification made by direct mixing of carbon paste with tris-4,7-diphenyl-1,10-phenanthroline-iron(II) perchlorate; the other is a glassy-carbon surface modified by oxidative electropolymerization of tris-[5-amino-1,10-phenanthroline]iron(II) perchlorate. Detection is accomplished by transporting an injected sample plug to the sensing surface with the aid of gravitational flow of an aqueous solution of supporting electrolyte. The polymer-coated electrochemical detector compares favourably with the chemically modified carbon paste. It offers excellent resistance to poisoning and a competitive limit of detection [about 2 ppb (2 parts in 10(9)) v/v], at + 1.0 V vs. Ag/AgCl, and good selectivity for NO(2) when used in a thin-layer cell. Incorporation of the cell in a continuous-flow system allows injection of about 120 samples per hour. The typical concentration range amenable to determination is 2-25 ppb v/v but depends on the thickness of the polymeric film. Nitrogen monoxide can also be detected but only in undiluted, pure form. Dinitrogen oxide gives no amperometric signal at any of the modified surfaces.
介绍了为在连续流动系统中测定氮氧化物而开发的两种化学修饰碳电极的安培性能。修饰包括固定可逆的Fe(II)/Fe(III)中心。第一种电极是通过将碳糊与高氯酸三 - 4,7 - 二苯基 - 1,10 - 菲咯啉铁(II)直接混合进行的简单修饰；另一种是通过高氯酸三 - [5 - 氨基 - 1,10 - 菲咯啉]铁(II)的氧化电聚合修饰的玻碳表面。检测是通过借助支持电解质水溶液的重力流将注入的样品塞传输到传感表面来完成的。聚合物涂层电化学检测器与化学修饰碳糊相比具有优势。在相对于Ag/AgCl为 + 1.0 V时，它具有出色的抗中毒能力和有竞争力的检测限[约2 ppb（10⁹份中的2份）v/v]，并且在薄层池中使用时对NO₂具有良好的选择性。将该池并入连续流动系统中允许每小时注入约120个样品。适合测定的典型浓度范围是2 - 25 ppb v/v，但这取决于聚合物膜的厚度。一氧化氮也可以被检测到，但仅以未稀释的纯形式。一氧化二氮在任何修饰表面都不会产生安培信号。
