Sensitive detection of polycyclic aromatic hydrocarbons with gold colloid coupled chloride ion SERS sensor

A simple surface-enhanced Raman spectroscopy (SERS) sensor based on an undecorated gold-colloid substrate was developed for the rapid and effective detection of polycyclic aromatic hydrocarbons (PAH). The SERS enhancement of the bare Au nanoparticles for PAH was achieved by adjusting chemical reduction conditions and Cl^- content. The strongest SERS response of this system was achieved with 2.0 mL of trisodium citrate (1%) and 80 μL of NaCl (1 M). With this simple SERS sensor, qualitative and quantitative determination of trace-level naphthalene (NaP), phenanthrene (PHE) and pyrene (PYR) were achieved using a portable Raman spectrometer at detection limits of 1.38 μg L^-1, 0.23 μg L^-1, and 0.45 μg L^-1, respectively. Plots of SERS intensity vs. PAH concentrations were linear, with correlation coefficients (R²) ranging from 0.8729 to 0.9994. More importantly, the SERS sensor was able to accurately identify each PAH in complex mixtures. This SERS technique shows great promise for the rapid and direct detection of aromatic hydrocarbons organic pollutants in field.