title: A colorimetric nitrite detection system with excellent selectivity and high sensitivity based on Ag@Au nanoparticles.
abstract: Excessive uptake of NO2(-) is detrimental to human health, but the currently available methods used to sensitively detect this ion in the environment are cumbersome and expensive. In this study, we developed an improved NO2(-) detection system based on a redox etching strategy of CTAB-stabilized Ag-Au core-shell nanoparticles (Ag@AuNPs). The detection mechanism was verified by UV-Vis spectroscopy, TEM and XPS. The detection system produces a color change from purple to colorless in response to an increase of NO2(-) concentration. The selectivity of detection of NO2(-), both with the unaided eye and by measurement of UV-Vis spectra, is excellent in relation to other ions, including Cu(2+), Co(2+), Ni(2+), Cr(3+), Al(3+), Pb(2+), Cd(2+), Ca(2+), Ba(2+), Zn(2+), Mn(2+), Mg(2+), Fe(3+), Hg(2+), Ag(+), K(+), F(-), PO4(3-), C2O4(2-), SO3(2-), CO3(2-), SO4(2-), NO3(-) and CH3-COO(-) (Ac(-)). The limit of detection (LOD) for NO2(-) is 1.0 μM by eye and 0.1 μM by UV-Vis spectroscopy. The LOD by eye is lower than the lowest previously reported value (4.0 μM). There is a good linear relationship between A/A0 and the concentration of NO2(-) from 1.0 to 20.0 μM NO2(-), which permits a quantitative assay. The applicability of our detection system was also verified by analysis of NO2(-) in tap water and lake water. The results demonstrate that our Ag@AuNP-based detection system can be used for the rapid colorimetric detection of NO2(-) in complex environmental samples, with excellent selectivity and high sensitivity.
authors.affiliation: Key Laboratory of Magnetic Materials and Devices, & Division of Functional Materials and Nano Devices, Ningbo Institute of Materials Technology & Engineering, Chinese Academy of Sciences, Ningbo, Zhejiang 315201, China. aiguo@nimte.ac.cn shenzheyu@nimte.ac.cn.
authors.forename: Tianhua
authors.initials: T
authors.lastname: Li
authors.forename: Yonglong
authors.initials: Y
authors.lastname: Li
authors.forename: Yujie
authors.initials: Y
authors.lastname: Zhang
authors.forename: Chen
authors.initials: C
authors.lastname: Dong
authors.forename: Zheyu
authors.initials: Z
authors.lastname: Shen
authors.forename: Aiguo
authors.initials: A
authors.lastname: Wu
mesh_terms: D000077286:Cetrimonium; D002593:Cetrimonium Compounds / Q000737:chemistry; D003124:Colorimetry / Q000379:methods*; D060766:Drinking Water / Q000032:analysis*; D004784:Environmental Monitoring / Q000379:methods; D006046:Gold / Q000737:chemistry*; D060106:Lakes / Q000032:analysis*; D057230:Limit of Detection; D053768:Metal Nanoparticles / Q000737:chemistry* / Q000648:ultrastructure; D009573:Nitrites / Q000032:analysis*; D012834:Silver / Q000737:chemistry*
chemical_list: D002593:Cetrimonium Compounds; D060766:Drinking Water; D009573:Nitrites; D012834:Silver; D006046:Gold; D000077286:Cetrimonium