Detection of nitroaromatic compounds

Detection of nitroaromatic compounds dissolved in liquid and supercritical C02 by UV-VIS spectroscopy... 

A measuring device is presented which is capable for the detection of nitroaromatic compounds dissolved in sub- and supercritical carbon dioxide by UV-VIS spectroscopy. The specific spectroscopic behavior of these solutions at pressures up to 400 bar and temperatures up to 150 °C is described. 

A measuring device was developed for the UV-VIS spectroscopic detection of nitroaromatic compounds dissolved in sub- and supercritical carbon dioxide. 

An extension of this work led to the pentiptycene-based PPEis 6a-c, suitable for the detection of nitroaromatic compounds. These PPEs 6 form in the Pd-catalyzed coupling of 4 to 2 or 5a (Chart 8.3). Dinitrotoluene is an electron-poor arene and its vapors efficiently quench the fluorescence of the PPE 6a efficiently. DNT is also the major decomposition product of TNT and therefore 6a senses explosives in a chemical-nose-type gadget. The quenching of PPEs fluorescence is superbly suited to sense and detect a number of other analytes. 

Kinetic simulation methods are used as advisory controls in potentially thermally hazardous batch amination reactions of nitroaromatic compounds. Time—temperature process data are fed as input to a kinetic simulation computer program which calculates conversions, heat release and pressure profdes. Results are compared continuously on-line with measured batch data to detect any deviations from normal operating conditions. 

Other materials were also employed to construct electrodes for amperometric detection. For instance, a boron-doped diamond (BOD) electrode was used for amperometric detection of nitroaromatic explosives, organophosphate nerve agents, and phenols. The BOD electrode offers enhanced sensitivity, lower noise, negligible adsorption of organic compounds, and low sensitivity to oxygen [760], In addition, a copper particle-modified carbon composite electrode was used for amperometric detection of glucose in a PDMS chip [761]. 

Electrode surface activation can be improved simply by electrochemical pretreatment. Determination of nitroaromatic compounds in water and soil spiked samples have been reported at electrochemically activated carbon-fiber microelectrodes. No interference was found from compounds such as hydrazine, phenolic compounds, carbamates, triazines or surfactants. The detection limit obtained can be approximately 0.03 iigml-1 for all the nitroaromatic compounds (Agui et al. 2005). Chen and coworkers reported an effective field-deployable tool for detecting nitroaromatic compounds with an electrochemically pre-anodized screen-printed carbon electrode (SPE) (Chen et al. 2006). 

M. laGrone, C. Cumming, M. Fisher, D. Reust and R. Taylor, Landmine detection by chemical signature detection of vapors of nitroaromatic compounds by fluorescence quenching of novel polymer materials, Proc. SPIE, Detection and Remediation Technologies for Mines and Minelike Targets IV, 3710 (1999) 409-420. 

The use of a near-field thermal lens system to increase pump beam absorption has recently been reported by Pyell and coworkers. This innovation has resulted in a nearly 30-fold improvement in detection limits for a multitude of nitroaromatic compounds, including a 0.15 mg/L detection limit (compared to a previously reported LOD of 3.4 mg/L) for 2-nitrotoluene. 

A SB-P-CD-assisted EKC method for the determination of cyclic nitramine explosives and related degradation intermediates and the 14 ERA listed explosives (borate/SDS electrolyte) has been described. " A volatile electrolyte composed of SB- -CD modified ammonium acetate buffer was selected for the EKC-MS detection of nitroaromatic and cyclic nitramine compounds in soil and marine sediment, as detailed in Table 31.7. The use of phosphate/SDS electrolytes was reported in the separation of the 14 listed nitramine and nitroaromatic explosives for the analysis of extracts of high explosives such as C-4, tetrytol, and detonating cord. " ... 

Groom, C.A.H. (2005) Detection of nitroaromatic and cychc nitramine compounds by cyclodextrin assisted capillary electrophoresis quadrupole ion trap mass spectrometry. Journal of Chromatography A, 1072,73-82. 

Environmental detection of toxic compounds harmful to human health, such as dihydroxybenzene, nitrite, nitrobenzene, and nitroaromatics in water, can also be carried out with sol-gel nanocomposite-based sensors. The electrochemical determination of these target analytes on a bare commercial solid electrode produces weak signals at high overpotentials. Taking advantage of the catalytic activity of metal nanoparticles, the sensitive electrochemical analysis of these... 

Hilmi et al. demonstrated a CE chip with direct amperometric detection for five nitroaromatic explosives, including trinitrotoluene (TNT), in ground water and soil extracts. The microfluidic device achieved rapid separation and detection of explosive compounds with LODs of 100-200 pg/L. 

Under the chosen conditions aromatic compounds are nitrated to nitroaromatics [1]. The detection of rotenone [1] (see below) depends on the reduction of silver ions, incorporated into the layer, to metallic silver in the presence of ammonia [4]. The mechanism of the reaction of many substances leading to fluorescent derivatives has not yet been elucidated [2],... 

An important demonstrated application of this artificial nose system is the high-speed detection of low levels of explosives and explosive-like vapors. Several sensors, based on Nile Red attached to silica microspheres, show high sensitivity to nitroaromatic compounds (NAC) within a mixture12. Different fluorescence response profiles were observed for several NAC s, such as 1,3,5-trinitrotoluene (TNT) and 1,3-dinitrobenzene (DNB), despite their similar structures. These responses were monitored at low concentrations of the NAC vapors (ca. 5 ppb) and at short vapor exposure... 

Other bacteria. Intestinal bacteria may play a critical role in the metabolic activation of certain nitroaromatic compounds in animals (119) and several reports have appeared on the metabolism of nitro PAHs by rat and human intestinal contents and microflora (120-123). Kinouchi et al. (120) found that 1-nitropyrene was reduced to 1-aminopyrene when incubated with human feces or anaerobic bacteria. More recently, Kinouchi and Ohnishi (121) isolated four nitroreductases from one of these anaerobic bacteria (Bacteroides fragilis). Each nitroreductase was capable of converting 1-nitropyrene into 1-aminopyrene, and one form catalyzed the formation of a reactive intermediate capable of binding DNA. Howard ej al. (116) confirmed the reduction of 1-nitropyrene to 1-aminopyrene by both mixed and purified cultures of intestinal bacteria. Two additional metabolites were also detected, one of which appeared to be 1-hydroxypyrene. Recently, similar experiments have demonstrated the rapid reduction of 6-nitro-BaP to 6-amino-BaP (123). 

LOD and LOQ were measured to assess the sensitivity of the FID, ECD and TSD detectors for GC analysis of various nitroaromatic compounds. A parallel connection of the three detectors at the end of a single narrow-bore capillary column enabled direct comparison of the chromatograms. Structural effects on the response were evaluated and detection mechanisms were discussed. Recommendations were made for identification purposes and for analysis of environmental samples of nitro- and chloro-nitro-benzenes in a wide range of concentrations451. 

A sensitive ELISA procedure was developed for the determination of TNT (221) and other nitroaromatic compounds. TNT can be detected within the range of 0.02-20 ng/L in water samples462. A simplified immunofiltration prepacked portable device for field screening tests of TNT in water and soil was also developed. A quantitative color response to concentrations of TNT in the range 1-30 ng/L in water and 50-1000 pg/g in soil was demonstrated463. 

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