title: Theoretical calculation (DFT), Raman and surface-enhanced Raman scattering (SERS) study of ponceau 4R.
abstract: Ponceau 4R is used as a coloring agent in many different products, such as food, drinks, medicines, cosmetics and tobacco. However, ponceau 4R also shows carcinogenic, teratogenic and mutagenic behavior in high doses. In this work, standard Raman, theoretical Raman and surface-enhanced Raman scattering (SERS) spectra have been used to investigate ponceau 4R. More specifically, density functional theory (DFT) calculations have been used to calculate the optimized Raman spectrum of ponceau 4R at the B3LYP/6-31G(d) level. This has provided a better understanding of the optimized geometry and vibrational frequencies of this dye. In addition, the experimental spectrum of ponceau 4R has been compared with the theoretical spectrum; good agreement was obtained. Finally, it has shown that using SERS the detection limit of the ponceau 4R solution can be as low as 5 μg/mL. This has been achieved by SERS measurements of ponceau 4R on a substrate of gold nanoparticles. The SERS peaks at 1030, 1236, 1356 and 1502 cm(-1) were chosen as index for semi-quantitative analysis, showing that the SERS technique provided a useful ultrasensitive method for the detection of ponceau 4R.
authors.affiliation: State Key Laboratory of Food Science and Technology, School of Food Science and Technology, Jiangnan University, 1800 Lihu Avenue, Wuxi, Jiangsu 214122, China.
authors.forename: Yunfei
authors.initials: Y
authors.lastname: Xie
authors.forename: Yan
authors.initials: Y
authors.lastname: Li
authors.forename: Yingying
authors.initials: Y
authors.lastname: Sun
authors.forename: Heya
authors.initials: H
authors.lastname: Wang
authors.forename: He
authors.initials: H
authors.lastname: Qian
authors.forename: Weirong
authors.initials: W
authors.lastname: Yao
mesh_terms: D001391:Azo Compounds / Q000737:chemistry*; D001419:Bacteria / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D008958:Models, Molecular; D009282:Naphthalenesulfonates; D011789:Quantum Theory; D013059:Spectrum Analysis, Raman; D014867:Water / Q000737:chemistry
chemical_list: D001391:Azo Compounds; D009282:Naphthalenesulfonates; D014867:Water; C576297:ponceau 4R