Development of a paper-based analytical device for the detection of polycyclic aromatic hydrocarbons (PAHs) using a...

Polycyclic aromatic hydrocarbons are persistent organic contaminants that are frequently reported at elevated concentrations in industrially and agriculturally impacted soils. Conventional PAH determination relies on solid phase extraction followed by chromatographic analysis, which offers high sensitivity but is limited by cost, time, and infrastructure requirements. In this study, a paper-based analytical device is developed as a complementary post extraction screening tool for PAHs at concentrations relevant to high loading soil environments. The device employs a horseradish peroxidase-hydrogen peroxide chromogenic substrate system, with colorimetric signals captured using a USB camera. Naphthalene, pyrene, and benz[α]anthracene were investigated as representative PAHs. The device exhibited concentration dependent responses over the 20 to 200 mM range, with limits of detection of 1.11 to 3.82 mM and signal development within 3 min. Optical characterization using UV-Vis and fluorescence spectroscopy supported the observed responses, while mechanistic and specificity studies indicated that signal generation was influenced by PAH-assay interactions under the applied reaction conditions. Application to soil matrix spiked samples following extraction demonstrated measurable responses that fell within the dynamic range of the calibration curves, although matrix-induced signal variation arising from co-extracted organic matter, residual extractants, and changes in optical scattering and wettability on the paper substrate was observed. These results demonstrate the feasibility of integrating enzyme-based paper devices into solid phase extraction centered analytical workflows as rapid and low cost screening tools for identifying elevated PAH levels in industrial and agricultural soils prior to confirmatory laboratory analysis.