title: A quantitative method for determination of Co(II) based on the inner filter effect of reagents on the Raman scattering signals of water.
abstract: It is known that Raman scattering signals are one of main interference sources leading up to determination errors in spectrofluorometry, and thus the signals can be easily detected with a common spectrofluorometer. In this contribution, we propose a quantitative method based on the inner filter effect (IFE) of reagents on the Raman scattering signals of solvent by taking the complexation of divalent cobalt ion with 4-[(5-chloro-2-pyridyl)azo]-1,3-diaminobenzene (5-Cl-PADAB) as a model system. By adjusting the excitation wavelength of the spectrofluorometer, we could easily detect the Raman scattering signals of water at 424 nm where the maximum absorption of 5-Cl-PADAB reagent is located. In a solution of 5-Cl-PADAB, the Raman scattering signals of water are decreased owing to the IFE of 5-Cl-PADAB. If Co(II), which could form the binary complex of Co(II)/5-Cl-PADAB and consumes the 5-Cl-PADAB reagent, is present in such a case for a given amount of 5-Cl-PADAB solution, recovered Raman scattering signals could be observed and measured with a spectrofluorometer. It was found that the intensity of the enhanced Raman scattering signals is proportional to the Co(II) concentration over the range from 2.0 x 10(-7) mol L(-1) to 1.0 x 10(-5) mol L(-1), and the detection limit could reach 1.2 x 10(-7) mol L(-1). With that, Co(II) in samples could be detected with R.S.D. values lower than 2.6% and recoveries over the range of 97.2-104.7%.
authors: Chongqing Municipal Key Laboratory on Luminescence and Real-Time Analysis, College of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715, PR China.
authors: Hui Ying
authors: HY
authors: Wang
authors: Cheng Zhi
authors: CZ
authors: Huang
mesh_terms: D000042:Absorption; D002623:Chemistry Techniques, Analytical / Q000379:methods; D003035:Cobalt / Q000032:analysis / Q000737:chemistry*; D005374:Filtration; D006863:Hydrogen-Ion Concentration; D007202:Indicators and Reagents; D008832:Microchemistry / Q000379:methods; D009942:Organometallic Compounds / Q000737:chemistry*; D010655:Phenylenediamines / Q000737:chemistry*; D012542:Scattering, Radiation; D012997:Solvents; D013050:Spectrometry, Fluorescence / Q000379:methods; D013059:Spectrum Analysis, Raman / Q000379:methods*; D014867:Water / Q000737:chemistry*
chemical_list: D007202:Indicators and Reagents; D009942:Organometallic Compounds; D010655:Phenylenediamines; D012997:Solvents; C104842:bis(4-((5-chloro-2-pyridyl)azo)-1,3-diaminobenzene)cobalt(II); D014867:Water; D003035:Cobalt