title: Innovative solid-state microelectrode for nitrite determination in a nitrifying granule.
abstract: Nitrite is an intermediate of both nitrification and denitrification in biological removal of nitrogen from wastewater, and in situ measurement of nitrite concentration in a biofilm or microbial granules is highly desirable. However, a solid-state microelectrode for nitrite determination is not available yet In this work, a solid-state microelectrode was manufactured through electrochemical codeposition of Pt--Fe nanoparticles on a gold microelectrode fabricated using photolithography for in situ nitrite determination. This gold-based microelectrode could be used as a more cost-effective, efficient, and reliable alternative to the liquid membrane microelectrode. Nanoparticles with an average diameter of 50 nm were observed on the surface of the chemically modified electrode. A sigmoid peak at ca. 0.7 V (vs Ag/AgCl) was found on the linear sweep voltammogram in nitrite solutions by using the fabricated microelectrode. The peak height of the first-order derivative of the sigmoid peak was proportional to the nitrite concentration of 0.001--0.05 M and could be used for quantitative determination of nitrite. The detection limits (S/N = 3) were approximately 3 x 10(-5) M. The nitrite microprofiles of aerobic granules from a nitrifying reactor were measured with the microelectrode to demonstrate its potential applications with high spatial resolution.
authors.affiliation: Department of Chemistry, University of Science & Technology of China, Hefei 230026, China.
authors.forename: Shao-Yang
authors.initials: SY
authors.lastname: Liu
authors.forename: You-Peng
authors.initials: YP
authors.lastname: Chen
authors.forename: Fang
authors.initials: F
authors.lastname: Fang
authors.forename: Shu-Hong
authors.initials: SH
authors.lastname: Li
authors.forename: Bing-Jie
authors.initials: BJ
authors.lastname: Ni
authors.forename: Gang
authors.initials: G
authors.lastname: Liu
authors.forename: Yang-Chao
authors.initials: YC
authors.lastname: Tian
authors.forename: Ying
authors.initials: Y
authors.lastname: Xiong
authors.forename: Han-Qing
authors.initials: HQ
authors.lastname: Yu
mesh_terms: D002138:Calibration; D006046:Gold; D008839:Microelectrodes; D008855:Microscopy, Electron, Scanning; D009573:Nitrites / Q000032:analysis*
chemical_list: D009573:Nitrites; D006046:Gold