Correction of the Effect of Humic Acids on the Fluorescence Detection of Polycyclic Aromatic Hydrocarbons by Combination Spectroscopy

Abstract

Polycyclic aromatic hydrocarbons (PAHs) are widely distributed in soil and water, but fluorescence spectroscopy for PAHs is often interfered with organic matter in the environment. The aim of this paper is to evaluate a correction method using combined spectral technology in an environment where humic acids and PAHs coexist. In the present work, humic acids and benzo[ghi]perylene were analyzed in various concentrations using fluorescence and near-infrared (NIR) spectroscopy from single and mixed samples. The NIR prediction model of humic acids in mixed samples was established based on synergy interval partial least squares, and the standard curve of fluorescence spectra for humic acids was established at 478 nm (characteristic wavelength of benzo[ghi]perylene). The fluorescence intensity of humic acids in the mixed sample was predicted from the content derived from the NIR spectra. The final correction was carried out by their exclusion from the fluorescence of the mixture at the same wavelength. The corrected fluorescence intensity was linearly correlated with the concentration of benzo[ghi]perylene with R²= 0.8362, while R²= 0.3538 before correction. These results give a new insight into the calibration modeling of the combined spectral method.

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