Optical sensing of explosives in wastewater by competitive complexation

A facile strategy for optical sensing of explosives with the assistance of 1,3,5-Triazine-2,4,6-triamine (MEL) in aqueous solution is proposed. Upon exposure to MEL, the electron-sufficient amino group in MEL was prone to form complexes with electron-deficient nitro group in explosives. The interaction could be tuned by the amount of MEL to fully consumed nitro-contained explosives dissolved in wastewater, thus prevented the gold nanoparticles (GNPs) from combining with MEL. In comparison with common detection method, the dose-response curve procedure reported here was in good linear relationship from 0 μM to 80 μM with good correlation factor (R² = 0.9871), and was satisfactorily agreed with the proposed theoretical model. The detection limit (LoD) was 1.1 μM by spectrometer, 3.0 μM visualized by naked eyes and 21.3 nM by calculation. The procedure described in this study could be finished within a few minutes and showed its effectiveness in explosive detection upright on the gold surface in real wastewater, making this proposed method a powerful tool in several sensing platforms.