Solid-phase extraction and SERS detection of pyrene on alumina gel with incorporated silver nanoparticles

Abstract

A promising approach for the simultaneous pre-concentration and determination of polycyclic aromatic hydrocarbons (PAHs), one of the priority environment pollutants, can be a combination of sorption and subsequent detection by surface-enhanced Raman scattering (SERS). In this paper, materials based on alumina containing silver nanoparticles (NPs) have been obtained, as well as the possibility of modification of these materials, their sorption properties and their application for determination by the SERS have been studied. A method of sorption pre-concentration in a static mode was used, and pyrene as a representative of PAH was chosen as a model analyte. Preliminary, silver NPs were obtained by the citrate reduction method, their size was 70±20 nm. An additional aggregation of silver NPs by sodium chloride was performed to enhance the SERS signal. Further, sorption of pyrene on the obtained alumina with embedded silver NPs was studied. However, the recovery of pyrene on this alumina gel did not exceed 68%, which can be explained by the hydrophilicity of the sorbent. To enhance the recovery of hydrophobic pyrene, surface modification of the sorbent with surfactants was carried out. As surfactant, aqueous and acidic solutions of sodium dodecyl sulfate (SDS) of various concentrations were used. An increase in the recovery of pyrene on sorbents modified by SDS was observed. The optimal conditions for modifying the sorbent are the concentration of SDS 1.4·10^{-2 M} and pure water as a solvent. Under the chosen conditions, an isotherm of sorption of pyrene on an alumina gel containing silver NPs was obtained, which obeys the Freundlich equation. Under optimal conditions, pyrene was pre-concentrated and determined directly in the solid phase by the SERS method.