Abstract:

Metal colloids immobilized on a glass support substrate are modified with a self-assembled alkylsilane (C18) layer to promote adsorption of polycyclic aromatic hydrocarbons from aqueous solutions. Detection of these compounds from low concentration solutions is accomplished by using surface-enhanced Raman scattering (SERS). SERS spectra of pyrene adsorbed to C18-modified immobilized silver colloids are dominated by Raman bands that are not consistent with pyrene and indicate that pyrene undergoes a chemical reaction at the surface. The origins of this surface product are investigated, and it is determined that silver and oxygen are required to form the product, whose Raman spectrum is consistent with oxidation to a quinone. When a C18-modified gold-colloid substrate is used, Raman scattering consistent with unreacted pyrene is observed. The adsorption and detection of pyrene adsorbed from low (2 ppb) concentration aqueous solutions onto C18-modified gold-colloid substrates is reported; naphthalene and phenanthrene are detected at ~5 ppb. Adsorption kinetics are rapid (<5 min), and the concentration-dependent SERS response is consistent with a Langmuir isotherm.

Keywords: SURFACE-ENHANCED RAMAN SPECTROSCOPY; SERS:; POLYCYCLIC AROMATIC HYDROCARBONS; PAH

Document Type: Research article

DOI: 10.1366/0003702042641380

Affiliations: 1: Department of Chemistry, University of Utah, 315 South 1400 East, Salt Lake City, Utah 84112-0850