A dynamic multichannel colorimetric sensor array for highly effective discrimination of ten explosives

We present a dynamic multichannel colorimetric sensor array for highly effective discrimination of ten explosives, including 2,4-dinitrotoluene, picric acid, hexahydro-1,3,5-trinitro-1,3,5-triazine, 3-nitro-1,2,4-triazol-5-one, hexanitrohexaazaisowurtzitane, 2,6-diamino-3,5-dinitropyrazine-1-oxide, 1,1-diamino-2,2-dinitroethene, 4-nitrophenol, nitroguanidine, and 2,4-dinitrophenol. This sensor array is based on the fact that the reduction of indigo carmine by dithiothreitol generates semi-leucoindigo carmine and leucoindigo carmine at the different reaction time, resulting in abundantly available absorption peaks at 456 nm, 504 nm, 552 nm, 612 nm, 754 nm, and 906 nm as the sensing elements. Because of the presence of the supramolecular interactions and chemical reactions between explosives and indigo carmine, the distinct absorbance responses to each explosive are created as an analytical fingerprint to discriminate and identify ten explosives. The present colorimetric sensor array can efficiently discriminate individual explosive at a concentration of 1.5 μM and binary explosive mixtures. Additionally, this sensor array has the capability to identify individual explosive in real water samples.