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1.
Summary A method for the gas chromatographic trace analysis of underivatized nitrophenols in ground-water is presented. Using a highly
de-activated separation system a satisfactory precision for their quantitative GC analysis could be achieved by avoiding condensation
of the solvent and by fast injection of the sample. The reproducibility of the peak areas of eleven nitrophenols in ethylacetate
was <5 % RSD. Using a nitrogen-phosphorus detector detection limits were in a range from 10 to 30 pg. Within the concentration
range from 0.1 to 10 ng μl−1 the calibrations were linear with correlation coefficients >0.992.
The approach described was applied to the analysis of nitrophenols in ground-water near a former ammunition plant, after preconcentration
by continuous liquid/liquid extraction with ethylacetate. Using a GC-MS technique and retention times various nitrophenols
were identified and then quantified in the μg/L-range by applying NPD. 相似文献
2.
We demonstrate that the selectivity of microchip electrophoresis separations is greatly improved by the presence of organically modified silica (Ormosil) sols in the run buffer. A negatively-charged N-(trimethoxysilylpropyl)ethylenediamine triacetic-acid (TETT)-based sol is used for improving the selectivity between nitroaromatic explosives and a methyltrimethoxysilane (MTMOS)-based sol is employed for enhancing the microchip separation of environmental pollutants, aminophenols. These sols are added to the run buffer and act as pseudostationary phases. Their presence in the run buffer changes the apparent mobility of studied solutes, and leads to a higher resolution. The observed mobilities changes reflect the interactions between the Ormosil sols and the solutes. Relevant experimental variables have been characterized and optimized. The diverse chemistry of Ormosil sols should be extremely useful for tailoring the selectivity of a wide range of electrophoresis microchip separations. 相似文献
3.
Summary A method has been developed for the determination of trace levels of 32 pesticides, 19 explosives and 16 polycyclic aromatic
hydrocarbons (PAH) in water in three individual steps. Solid-phase enrichment (SPE) is coupled to high-performance liquid
chromatography (HPLC) with a fully automated system. The organic pollutants are enriched on reusable cartridges packed with
adsorbent materials: pesticides and explosives on a mixed bed of divinylbenzene-ethylvinylbenzene copolymers (LiChrolut EN?) and perfluorinated polyethylene (PolyF?), and polycyclic aromatic hydrocarbons on C18-modified silica (Zorbax? ODS1). Thermally assisted desorption (TAD) has been shown to increase the recovery of analytes significantly. As all enriched
analytes are transferred to the detector, only fifty millilitres of sample is needed for each single on-line analysis, compared
with at least a litre for conventional methods. The separation of the enriched organic analytes is performed on specialized
HPLC columns based on reversed-phase materials. The limits of detection of the system employed were found to be below 100
ng L−1. Use of fluorescence detection for the polycyclic aromatic hydrocarbons resulted in limits of detection in the upper pg L−1 range. Thek values, number of theoretical plates, the recovery rates and the limits of detection of this method for fast screening of
organic pollutants from three fifty-millilitre aqueous samples are described.
Presented at the 21st ISC held in Stuttgart, Germany, 15th–20th September, 1996 相似文献
4.
5.
Lemi Türker 《无机化学与普通化学杂志》2013,639(1):169-175
A physical model and a mathematical theory for the detonation pressures of explosives materials were developed. The pressure values are expressed as function of the detonation velocity (D) and the average mass (m) of the gaseous products, and are applied for various nitramines and aromatic nitro compounds including nitro pyrimidines and nitro triazines. Some regression equations were obtained and discussed. The pressure values show poor linear dependence on the average mass of the products but good dependence on the detonation velocities alone or Dm. Moreover, for the same Dm value nitramines should produce more pressure than aromatic nitro compounds. This work deals with pressure developed by explosion products and interrelates it with detonation pressure within the constraints of certain assumptions and pays attention to so far unnoticed relationships at least under certain circumstances. 相似文献
6.
Lemi Türker 《无机化学与普通化学杂志》2014,640(10):2025-2029
By computational studies it was found that interaction of an α‐particle with TEX (an explosive molecule having a cage structure) disturbs the molecular skeleton dramatically. As the α‐particle exerts its positive electrostatic field, the C–C bond between the dioxalane rings present in TEX breaks down forming the dication of TEX. The calculation were done within the constraints of the density functional theory at the level of B3LYP using various bases sets, mainly 6‐31++G(d,p). 相似文献
7.
8.
Bai Sun Minqiang Li Fang Zhang Yu Zhong Nansheng Kang Wei Lu Jinhuai Liu 《Microchemical Journal》2010,95(2):293-297
A prototype setup for detecting illicit materials by energy-dispersive X-ray diffraction (EDXRD) has been developed. The obtained results of NaCl by the equipment suggest that the total measurement system is reliable and can be used to detect different kinds of materials. The tests of TNT, methamphetamine and heroin are also performed on this equipment and the related EDXRD spectra are obviously influenced by the detecting angle and the X-ray sources. The detecting angle of 10° is more suitable for detecting TNT and methamphetamine, while 12° is better for heroin. Moreover, the curves of TNT, methamphetamine and heroin emitted by W target have more diffraction peaks than those emitted by Cu or Mo target, while the peak intensities of TNT and methamphetamine emitted by Mo are stronger than those emitted by Cu or W target. The curve of methamphetamine emitted by Mo target shows a special characteristic and exhibits a super strong diffraction peak located at 1.62 Å− 1, which can be attributed to the effect arising from Mo kα and kβ. 相似文献
9.
Mariana R. Almeida Deleon N. Correa Jorge J. Zacca Lucio Paulo Lima Logrado Ronei J. Poppi 《Analytica chimica acta》2015
The aim of this study was to develop a methodology using Raman hyperspectral imaging and chemometric methods for identification of pre- and post-blast explosive residues on banknote surfaces. The explosives studied were of military, commercial and propellant uses. After the acquisition of the hyperspectral imaging, independent component analysis (ICA) was applied to extract the pure spectra and the distribution of the corresponding image constituents. The performance of the methodology was evaluated by the explained variance and the lack of fit of the models, by comparing the ICA recovered spectra with the reference spectra using correlation coefficients and by the presence of rotational ambiguity in the ICA solutions. The methodology was applied to forensic samples to solve an automated teller machine explosion case. Independent component analysis proved to be a suitable method of resolving curves, achieving equivalent performance with the multivariate curve resolution with alternating least squares (MCR-ALS) method. At low concentrations, MCR-ALS presents some limitations, as it did not provide the correct solution. The detection limit of the methodology presented in this study was 50 μg cm−2. 相似文献
10.
This paper reports on a microfluidic device for the flow-injection/electrochemistry analysis of nitroaromatic explosive. The response is very fast (150 assays/h), highly sensitive (detection limit 7.0 μg L−1), reproducible and stable (R.S.D. = 2.0%; n = 30) and linear (over 20-100 μg L−1 range). Relevant experimental parameters have been optimized. The new microsystem offers great promise for on-site monitoring of TNT, with significant advantages of speed/warning, sample size, efficiency and cost. Most favorable S/N characteristics were obtained at the Hg/Au-amalgam end-channel detector. 相似文献