Abstract：Polychlorinated biphenyls (PCBs) in marine pollution monitoring is widely attention. In this paper, surface-enhanced Raman spectroscopy (SERS) and density functional theory (DFT) methods were used to investigate the Raman spectra differences of four representatives PCBs (PCB15, PCB28, PCB47 and PCB77) and their adsorption properties on gold nanoparticles. The influence of different adsorption characteristics on SERS quantitative detection was also analyzed. Firstly, the Raman spectra and vibration mode contributions of PCBs were calculated and compared with the measured results to assign the Raman peaks. Then, the PCBs-Au adsorption system was constructed and its binding energy and molecular spatial structure changes before and after adsorption were calculated to predict the adsorption characteristics of molecules on the gold substrate. Finally, the gold colloid was used as the SERS enhanced substrate for SERS detection to reflect the influence of adsorption characteristics on quantitative analysis. The results showed that the calculated results agreed with the measured spectra. The common characteristic peaks of PCBs included bridge bond stretching vibration peak (around 1 290 cm-1), ring breathing vibration peak (around 1 000 cm-1), and ring stretching vibration peak (around 1590 cm-1). The difference of substituted position of Cl atom has a significant effect on Raman vibration, which eventually complicate the vibration peaks of the C—Cl bond and C—H bond. The adsorption capacity from high to low was PCB15 (-6.46 kcal·mol-1), PCB28 (-3.01 kcal·mol-1), PCB77 (-1.95 kcal·mol-1) and PCB47 (-0.31 kcal·mol-1), and the number of substituted chlorine and the ortho-substitution of Cl atom decrease the binding energy and the adsorption form of the molecule on the gold substrate. The increase of the number of ortho-substitutions of the bridge bond leads to the increase of steric hindrance, which hinders the adsorption of molecules. The adsorption characteristics affected the SERS quantification. There was a good linear relationship between the SERS peak intensity and concentration. Molecules with strong adsorption ability in a water environment are more likely to reach the saturation state first, and have the lowest detection concentration. The above conclusion laid a theoretical foundation for SERS technology to detect and identify PCBs in the marine environments and for quantitative analysis.
宋洪艳，赵 航，严 霞，史晓凤，马 君. 基于表面增强拉曼光谱技术的海洋污染物多氯联苯吸附特性分析[J]. 光谱学与光谱分析, 2022, 42(03): 704-712.
SONG Hong-yan, ZHAO Hang, YAN Xia, SHI Xiao-feng, MA Jun. Adsorption Characteristics of Marine Contaminant Polychlorinated Biphenyls Based on Surface-Enhanced Raman Spectroscopy. SPECTROSCOPY AND SPECTRAL ANALYSIS, 2022, 42(03): 704-712.
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