Department of Chemistry, University of Bath, Bath BA2 7AY, UK.
Department of Chemistry, University of Bath, Bath BA2 7AY, UK.
Talanta. 2015 Jan;131:228-35. doi: 10.1016/j.talanta.2014.07.084. Epub 2014 Aug 5.
A dual-electrode sensor is developed for rapid detection of nitrite/nitrate at micromolar levels in phosphate buffer media and in dilute horse serum without additional sample pre-treatment. A generator-collector configuration is employed so that on one electrode nitrate is reduced to nitrite and on the second electrode nitrite is oxidised back to nitrate. The resulting redox cycle gives rise to a specific and enhanced current signal which is exploited for sensitive and reliable measurement of nitrite/nitrate in the presence of oxygen. The electrode design is based on a dual-plate microtrench (approximately 15 µm inter-electrode gap) fabricated from gold-coated glass and with a nano-silver catalyst for the reduction of nitrate. Fine tuning of the phosphate buffer pH is crucial for maximising collector current signals whilst minimising unwanted gold surface oxidation. A limit of detection of 24 μM nitrate and a linear concentration range of 200-1400 μM is reported for the microtrench sensor in phosphate buffer and dilute horse serum. Relative standard deviations for repeat measurements were in the range 1.8-6.9% (n=3) indicating good repeatability in both aqueous and biological media. Preliminary method validation against the standard chemiluminescence method used in medical laboratories is reported for nitrate analysis in serum.
一种双电极传感器被开发出来，用于在磷酸盐缓冲介质和稀释的马血清中无需额外的样品预处理，快速检测亚硝酸盐/硝酸盐在微摩尔水平。采用了发生器-收集器配置，使得在一个电极上硝酸盐还原为亚硝酸盐，而在第二个电极上亚硝酸盐被氧化回硝酸盐。由此产生的氧化还原循环产生了一个特定的增强电流信号，该信号被用于在存在氧气的情况下对亚硝酸盐/硝酸盐进行敏感和可靠的测量。该电极设计基于双极板微沟（约 15 µm 电极间隙），由镀金玻璃制成，并具有纳米银催化剂用于还原硝酸盐。精细调整磷酸盐缓冲液的 pH 值对于最大化收集器电流信号至关重要，同时最小化不需要的金表面氧化。在磷酸盐缓冲液和稀释的马血清中，微沟传感器的硝酸盐检测限为 24 μM，线性浓度范围为 200-1400 μM。在水相和生物介质中，重复测量的相对标准偏差在 1.8-6.9%（n=3）范围内，表明重复性良好。报告了针对医学实验室中使用的标准化学发光法的初步方法验证，用于血清中的硝酸盐分析。
