Rapid on-site detection of substituted aromatic compounds in firefighting wastewater using thin-layer chromatography tandem with surface-enhanced Raman spectroscopy.

Rapid identification of hazardous aromatic pollutants in complex environmental matrices remains a major challenge for emergency environmental monitoring, particularly in firefighting wastewater containing severe matrix interference and multiple coexisting contaminants. Herein, we report a thin-layer chromatography-surface-enhanced Raman scattering (TLC-SERS) platform based on plasmonic Au colloids for the rapid separation, fingerprint identification, and quantitative detection of substituted aromatic pollutants. Au nanoparticles were prepared by seed-mediated growth using citrate-reduced seeds. The platform separated four substituted aromatic compounds, including p-phenylenediamine, o-phenylenediamine, benzidine, and 4-chlorophenol, in a standard mixture and enabled their identification by matching the SERS spectra of the resolved spots to those of individual standards. Analyte-specific calibration curves were established for quantitative analysis after a common TLC separation and sequential SERS measurements. Compared with direct SERS, TLC separation reduced spectral overlap and enabled component-specific analysis. Application to spiked firefighting wastewater enabled the identification and quantification of p-phenylenediamine, o-phenylenediamine, and 4-chlorophenol in recovery experiments, with measured concentrations agreeing with the added concentrations. These results demonstrate analytical performance for added analytes in a real wastewater matrix. With filtration as the only sample pretreatment before TLC, the platform provides an approach to multicomponent analysis of substituted aromatic pollutants and a basis for on-site environmental monitoring and emergency screening of hazardous aromatic contaminants in natural waters and industrial wastewater systems.