Poly[meso-tetrakis(2-thienyl)porphyrin] for the sensitive electrochemical detection of explosives

Poly[meso-tetrakis(2-thienyl)porphyrin] (pTTP) was prepared through electrochemical polymerization of meso-tetrakis(2-thienyl)porphyrin (TTP). The pTTP film thus generated was characterized by cyclic voltammetry (CV), SEM, and Raman spectroscopy. The ability of the pTTP-modified electrode for the detection of a range of explosives in aqueous solution was investigated using differential pulse voltammetry (DPV). The results demonstrate that pTTP film greatly enhances the reduction of 2,4-DNT, TNT, Tetryl, RDX, and nitromethane when compared to an unmodified electrode, a TTP-modified electrode, or a polythiophene-modified electrode. This may be attributed to the high affinity of the porphyrin ring in the pTTP conducting chain to the nitrocompound and the resulting enhanced electron transfer during the explosives reduction. Under optimized conditions, the pTTP-modified electrode shows a limit of detection (S/N = 3) as low as 8 ppb for 2,4-DNT and TNT, 9 ppb of Tetryl, 96 ppb of RDX, and 43 ppb of nitromethane without requiring any sample pre-concentration step. This study indicates that pTTP can serve as a new class of material in the electrochemical detection of explosives.