A flow-drop electrochemiluminescent design for portable detection of soil and skin 2,4,6-trinitrotoluene

Abstract

An automatic miniaturized flow-drop electrochemiluminescence (ECL) technique was established by utilizing a coalescing drop as a wall-less electrolytic cell, a self-driven mixer, and a µL scale reactor. Cost-effective ECL detection of 2,4,6-trinitrotoluene (TNT) was proposed, by virtue of the finding of the enhancement on luminol ECL by trace TNT in alkaline aqueous medium. The mechanism of TNT intensifying luminol ECL was suggested as that the one-electron reduction of TNT yielded TNT anion radical converts dissolved oxygen into superoxide anion radical, which subsequently reacted with luminol to produce luminol anion radical, finally resulting in the acceleration of luminol oxidation. By optimizing all the experimental conditions, the intensified ECL was found to be linear to TNT concentration over the 5–100 nM range, with a limit of detection of 0.5 nM. The method’s precision and accuracy were examined via F and t tests. The feasibility of this portable ECL method was validated by determining unknown TNT contents in real soil and finger skin samples via parallel official method. All results support the technique as a robust alternative for on-site TNT detection for environmental and forensic purposes.