A field-applicable colorimetric assay for notorious explosive triacetone triperoxide through nanozyme-catalyzed irreversible oxidation of 3, 3'-diaminobenzidine.

A field-applicable colorimetric assay for fast detection of notorious explosive triacetone triperoxide (TATP) has been developed through the selective irreversible oxidation of 3, 3'-diaminobenzidine by hydrogen peroxide (HP) liberated during the acidic hydrolysis/degradation of TATP in the presence of MnO nanozymes. The generated HP was detected by probing the absorbance of the product (indamine polymer) of the 3, 3'-diaminobenzidine (DAB) oxidation reaction at 460.0 nm. The UV-Vis measurements provided a linear range from 1.57 to 10.50 mg L TATP with a detection limit of 0.34 mg L. The oxidation of DAB cannot proceed by molecular oxygen, thus it is selectively oxidized by HO; this prevents false-positive results from laundry detergents (containing O-releasing substances). Moreover, a naked-eye field test was developed, and a fast spot test analyzing time of 5 s was achieved. The selectivity of the assay was checked by analyzing some synthetic samples prepared with a laundry detergent as camouflage. The results of the developed assay revealed quantitative recoveries for TATP whereas the standard nanozyme-based method showed significant false-positive results. Graphical abstract.