Fluorescence of Aromatic Amines and Their Fluorescamine Derivatives for Detection of Explosive Vapors

Abstract

Nitroaromatics (such as dinitrotoluene, trinitrotoluene, and nitrobenzene) found in explosive vapors from buried landmines can be reduced to aminoaromatics by a novel process involving Pd metal nanocatalysts prepared in supercritical fluid carbon dioxide and supported on multi-walled carbon nanotubes. These aminoaromatics are fluorescent and, if desired, the fluorescence yield can be increased and the fluorescence maxima shifted further toward the red by reaction with appropriate derivatizing agents such as fluorescamine. Corrected spectra for these chemicals and their derivatives are included. Subpicomolar detection limits have already been achieved using a laboratory spectrofluorometer with a 150 W Xe arc lamp. Using lasers as excitation sources, this approach has the potential for developing a field sensor competitive with other methods currently used for detecting explosive vapors from land mines.

Increasing Selectivity for TNT-Based Explosive Detection by Synchronous Luminescence and Derivative Spectroscopy with Quantum Yields of Selected Aromatic Amines

“…For the SL studies (Dk ¼ 9.0 nm), it was determined that the detection limits for 2,4-DAT, 2,6-DAT, ptoluidine, and o-toluidine were 2.6 3 10 À6 M, 2.3 3 10 À6 M, 6.7 3 10 À7 M, and 1.7 3 10 À7 M, respectively. The data presented within this research paper were obtained in ethanol solutions; however, from preliminary data acquired from previous research, 7 we anticipate that the same results will be obtained in a gas-phase sample. By using a more sensitive detector, and a more intense excitation source, a decrease in the detection limit can potentially be achieved.…”

“…Our group recently studied the excitation and emission spectra of these and several other compounds. 7 Due to the broad FWHM of these compounds, when overlaying the emission spectra of the three compounds, it is evident that the emission spectra would not yield adequate separation (Fig. 1, top).…”

“…As already discussed in previous research, 7 experiments were carried out using a Spex (HORIBA Jobin Yvon) analytical grade spectrofluorometer (FluoroMax-3 TM ) with a 150 watt xenon arc lamp. The instrument was calibrated by measuring the spectrum of the xenon lamp for the excitation monochromator (wavelength calibration and intensity) and measuring the water Raman peak for the emission monochromator (wavelength calibration and intensity).…”

“…6 Previous research done by our group 7 shows that the reduction of nitro aromatics to aromatic amines can be accomplished in one minute by using catalytic metallic (Pd) nanoparticles, synthesized in supercritical fluid carbon dioxide and subsequently supported on carbon nanotubes. 8 In this previous research, we provided preliminary data 7 indicating that 2,4-DNT vapor can be collected and rapidly reduced to 2,4-DAT, thereby allowing for fluorescence analysis. Therefore, after this method of rapid reduction, fluorescence studies of the explosive vapors trapped in ethanol solution or potentially front surface on suitable substrates can occur.…”

Gram scale synthesis of Fe/FexOycore–shell nanoparticles and their incorporation into matrix-free superparamagnetic nanocomposites

“…We then introduced a small quantity of fluorescamine, which is a spiro compound that forms highly fluorescent pyrrolinones upon reaction with primary and secondary amines. 41,42 Following the reaction with fluorescamine, the nanoparticles were washed thoroughly with hexane and methanol using magnetic separation to remove any unreacted fluorescamine. The nanoparticles were then measured using a spectrofluorometer with an excitation wave length of 390 nm.…”