title: Chemical analysis of polycyclic aromatic hydrocarbons by surface-enhanced Raman spectroscopy.
abstract: The use of surface-enhanced Raman spectroscopy (SERS) for trace determination of polycyclic aromatic hydrocarbons (PAHs) is described. This paper focuses on the development of SERS-active substrates that are specific for the characterization and spectroscopic study of PAHs. The SERS-active substrates are based on thin gold films evaporated on a glass surface previously treated with a mercaptoalkylsilane. SERS of PAHs was investigated over uncoated gold island films and over such films coated with a self-assembled monolayer (SAM) of 1-propanethiol. Adsorption of PAHs on a plain SERS-active Au-film led to a surface-induced decomposition of PAHs, due to catalytic properties of nanostructured gold. Thus, the functionalization of the SERS-active substrates by means of SAM was done aiming at a specific chemical interaction toward PAHs. Thus, in addition to preventing decomposition of the PAHs, the coating also concentrates the hydrophobic PAHs close enough to the SERS-active interface. Results show that high sensitivity, SERS-active nanostructured gold substrates that show selectivity towards PAHs were obtained, with the following properties: strong intensification of the Raman signal, reproducibility, and stability over time. The employed methodology enables the observation of excellent Raman spectra of PAHs in aqueous environment at ppm levels.
authors.affiliation: Instituto de Química, Universidade de São Paulo, Av. Prof. Lineu Prestes, 748 São Paulo, SP, Brasil.
authors.forename: J C S
authors.initials: JC
authors.lastname: Costa
authors.forename: A C
authors.initials: AC
authors.lastname: Sant'ana
authors.forename: P
authors.initials: P
authors.lastname: Corio
authors.forename: M L A
authors.initials: ML
authors.lastname: Temperini