Direct colorimetric detection of triacetone triperoxide explosive by hydroxylamine-mediated Fenton chemistry catalyzed by goethite nanoparticles

Abstract

Due to the absence of nitro groups or aromatic structures in its structure, spectrophotometric methods that can directly determine triacetone triperoxide (TATP) are absent. In the proposed study, a molecular spectroscopic sensor was developed based on the decomposition of TATP by hydrolysis without the addition of external acid, allowing the direct determination of TATP. The detection principle of the developed sensor is based on the decomposition of TATP by the hydrochloric acid formed as a result of the reaction of TATP with hydroxylamine hydrochloride, taking advantage of the solubility of TATP in acetone, and the hydrogen peroxide formed as a degradation product to form hydroxyl radicals catalyzed by goethite nanoparticles. The formed hydroxyl radi cals, thanks to their strong oxidation properties, oxidized N,N-dimethyl-p-phenylenediamine (DMPD) to the pink colored DMPD•+ radical cation, and the direct determination of TATP was performed by measuring the absor bance of the colored product formed. Thus, a chemo-cybernetic sequence of reactions is proposed for intact TATP assay in a circular self-sustained system, where the reactants at a given step of reactions are supplied by the products of a previous step. By applying the developed method to TATP samples prepared in acetone, absor bances due to DMPD•+ were read at 554 nm to evaluate the results. A calibration curve was created between absorbance versus TATP concentration within a final range of 10 – 33 mg L-1. The limit of detection (LOD) and limit of quantification (LOQ) of the developed TATP method were 3.3 mg L-1 and 10.8 mg L-1, respectively. Five replicate measurements were performed to determine the intra-assay and inter-assay precision of the spectro photometric determination of TATP, and the relative standard deviations (RSD %) for TATP were found as 2.70 % and 3.76 %, respectively. Interference analysis was carried out to see the effects of ions commonly present in soil/groundwater, and of the substances used as camouflage materials due to their color and appearance simi larity to TATP. The selectivity of the method toward TATP was investigated by examining the analyte recovery from explosive mixtures. The developed method was validated against a reference GC–MS method using TATP contaminated soil samples, and the results were compared statistically.