Surface-enhanced Raman scattering technique for polycyclic aromatic hydrocarbons detection using thiol-functionalized silver nanoparticle films

Abstract

The detection of polycyclic aromatic hydrocarbons (PAHs) is developed based on surface-enhanced Raman scattering (SERS) using silver nanoparticle films as SERS substrates. The films are fabricated by a Langmuir Blodgett (LB) method and the surface of AgNP films are functionalized with various types of aromatic and aliphatic thiols, i.e., naphthalenethiol, phenylethanethiol, pentanethiol, octanethiol, and dodecanethiol, to create a hydrophobic layer for PAHs to attach on and stay in hot spot. The results indicate that nine kinds of PAHs with different structures, i.e., anthracene, chrysene, naphthacene, naphthalene, phenanthrene, pentacene, perylene, pyrene, and triphenylene, can attach on the surfaces of thiol-modified AgNP films as SERS spectra show characteristic patterns for each PAH. Chemometrics methods, i.e., principle component analysis (PCA), cluster separation, partial least square (PLS) regression, and leave-one-out cross validation (LOOCV), are employed for qualitative and quantitative analysis. They show an effective analysis of pure PAH (at the concentration ranging from 10-4–10-7 M) results with the R2 more than 0.9800 and Q2 (R2 of cross-validation model) more than 0.9300. The mixture of two PAHs can be determined with the R2 more than 0.9700 and Q2 more than 0.8900. Moreover, the total concentration of PAHs in the mixture of nine different PAHs can be analyzed with the R2 = 0.9700 and Q2 = 0.9196. This technique can be used to detect PAHs in real sample such as detect PAH in water matrix. SERS technique provides an advantage of sample analysis which does not require any complicated sample pretreatment, convenient and rapid in situ analysis with high sensitivity results.