Inkjet-printed low-cost colorimetric tickets for TNT detection in contaminated soil

A simple colorimetric detection method for 2,4,6-trinitrotoluene (TNT) in contaminated soil has been developed. Procedurally, a TNT responsive chromogenic reagent was inkjet printed on commercially available photo paper, and the resulting colorimetric ticket was laminated with a precut patterned film to make a bilayer microfluidic sensor. For the TNT detection experiments, a drop of TNT solution was placed on the center of the prepared sensor. Color measurement of the sensor with a photo scanner showed a wide detection range of TNT, ranging from 14 parts per million (ppm), which is below its residential screening level (∼21 ppm) to 7,200 ppm. To further demonstrate its efficacy, TNT spiked soil samples were extracted with acetone and evaluated with the developed sensor.