title: Diazotization-coupling reaction-based selective determination of nitrite in complex samples using shell-isolated nanoparticle-enhanced Raman spectroscopy.
abstract: A simple, rapid and selective method based on diazotization-coupling reaction for determination of nitrite ion in complex samples using shell-isolated nanoparticle-enhanced Raman spectroscopy (SHINERS) was developed. Based on diazotization-coupling reaction, nitrite was transformed into azo dye, which has strong SHINERS activity. Subsequently the concentration of nitrite ion can be determined indirectly from the SHINERS of azo dye. The SHINERS active substrate was composed of gold nanoparticle as core with an ultrathin silica shell having pinhole on the surface. Various factors that influence reaction and SHINERS intensity were investigated. Under the optimal conditions, the linearity was observed in the range of 0.5-6.0 mg L(-1) with good correlation coefficient (r(2)>0.9793). The relative standard deviations (RSDs) for five replicate measurements were less than 14.5%. The limit of detections of the method (S/N=3) were 0.07, 0.08 and 0.10 mg L(-1) at 1137, 1395 and 1432 cm(-1), respectively, without sample preconcentration. The selectivity of the proposed method was also tested. The performance of SHINERS to determine the concentration of nitrite in food, biological and environmental samples was evaluated. The results indicate that SHINERS shows great potential as a useful analytical tool for trace analysis of nitrite in real samples. This proposed method provides a practical protocol for determination of compounds with weak Raman response, and can be expanded for the indirect detection of iodate ion, phenols and aromatic amines.
authors.affiliation: School of Chemistry and Chemical Engineering, Sun Yat-sen University, Guangzhou, Guangdong 510275, PR China.
authors.forename: Kaige
authors.initials: K
authors.lastname: Zhang
authors.forename: Yuling
authors.initials: Y
authors.lastname: Hu
authors.forename: Gongke
authors.initials: G
authors.lastname: Li
mesh_terms: D000814:Aniline Compounds / Q000737:chemistry; D001391:Azo Compounds / Q000737:chemistry*; D004159:Diphenylamine / Q000737:chemistry; D060766:Drinking Water / Q000737:chemistry*; D005618:Fresh Water / Q000737:chemistry*; D006046:Gold / Q000737:chemistry; D006801:Humans; D057230:Limit of Detection; D053768:Metal Nanoparticles / Q000737:chemistry*; D009573:Nitrites / Q000032:analysis*; D012822:Silicon Dioxide / Q000737:chemistry; D013059:Spectrum Analysis, Raman; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D000814:Aniline Compounds; D001391:Azo Compounds; D060766:Drinking Water; D009573:Nitrites; D014874:Water Pollutants, Chemical; C008625:nitroaniline; D006046:Gold; D012822:Silicon Dioxide; D004159:Diphenylamine
keywords: Diazotization-coupling reaction; Gold nanoparticles with an ultrathin silica; Nitrite ion; Shell-isolated nanoparticle-enhanced Raman spectroscopy