Study on fluorescence interaction between humic acid and PAHs based on two-dimensional correlation spectroscopy

Abstract

Polycyclic aromatic hydrocarbons (PAHs) pollution is an increasingly serious environmental problem, and the effective and rapid detection of PAHs is in urgent need for environment management and remediation. At present, fluorescence technology is the preferred method for fast in-situ dynamic detection of PAHs. However, the impact of humic acid on PAHs fluorescence has become a bottleneck for accurate detection of PAHs using this technology. In this work, 2D correlation analysis is used to study the interaction between the fluorescence spectroscopy of humic acid and benzo[ghi]perylene (BGP), a typical molecule in the PAHs family. First of all, the fluorescence characteristics of BGP and humic acid were analyzed and feature peaks were identified separately. Meanwhile, the fluorescence spectra of humic acids at various concentrations excited at different wavelengths were obtained to analyze the variation of fluorescence intensity with concentration for different groups of humic acid. Secondly, the conventional one-dimensional fluorescence spectra of the mixed samples of different concentrations of humic acids with fixed BGP concentration were studied to explore the effect of humic acid on the fluorescence of BGP. Finally, 2D correlation fluorescence spectra of the mixed samples of humic acid and BGP were studied with excitation wavelength as the external perturbation. The results showed that humic acid had a significant effect on the fluorescence intensity of BGP, and indicated that high concentration of humic acid could lead to fluorescence quenching of BGP. And the fluorescence characteristic information of humic acid with lower concentration could be extracted from sliced asynchronous spectrum at the signature peak of BGP. This study demonstrated a novel approach for the separation of fluorescence intensities of humic acid from PAHs, providing corrected PAHs spectra for quantitative analysis of the mixture.