共查询到20条相似文献,搜索用时 31 毫秒
1.
Thomas A. Blake James F. Kelly Neal B. Gallagher Paul L. Gassman Timothy J. Johnson 《Analytical and bioanalytical chemistry》2009,395(2):337-348
Hyperspectral images of galvanized steel plates, each containing a stain of cyclotrimethylenetrinitramine (RDX), were recorded
using a commercial long-wave infrared imaging spectrometer. Demonstrations of passive RDX chemical detection at areal dosages
between 16 and 90 μg/cm2 were carried out over practical standoff ranges between 14 and 50 m. Anomaly and target detection algorithms were applied
to the images to determine the effect of areal dosage and sensing distance on detection performance for target RDX. The anomaly
detection algorithms included principal component analysis, maximum autocorrelation factors, and principal autocorrelation
factors. Maximum difference factors and principal difference factors are novel multivariate edge detection techniques that
were examined for their utility in detection of the RDX stains in the images. A target detection algorithm based on generalized
least squares was applied to the images, as well, to see if the algorithm can identify the compound in the stains on the plates
using laboratory reflection spectra of RDX, cyclotetramethylenetetranitramine (HMX), and 2,4,6-trinitrotoluene (TNT) as the
target spectra. The algorithm could easily distinguish between the nitroaromatic (TNT) compound and the nitramine (RDX, HMX)
compounds, and, though the distinction between RDX and HMX was less clear, the mean weighted residuals identified RDX as the
stain on the plate. Improvements that can be made in this detection technique are discussed in detail. As expected, it was
found that detection was best for short distances and higher areal dosages. However, the target was easily detected at all
distances and areal dosages used in this study.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
2.
Monterola MP Smith BW Omenetto N Winefordner JD 《Analytical and bioanalytical chemistry》2008,391(7):2617-2626
A simple, fast, reliable, sensitive and potentially portable explosive detection device was developed employing laser photofragmentation
(PF) followed by heterogeneous chemiluminescence (CL) detection. The PF process involves the release of NOx(x = 1,2) moieties from explosive compounds such as TNT, RDX, and PETN through a stepwise excitation–dissociation process using a 193 nm
ArF laser. The NOx(x = 1,2) produced upon PF is subsequently detected by its CL reaction with basic luminol solution. The intensity of the CL signal
was detected by a thermoelectrically cooled photomultiplier tube with high quantum efficiency and negligible dark current
counts. The system was able to detect trace amounts of explosives in various forms in real time under ambient conditions.
Detection limits of 3 ppbv for PETN, 2 ppbv for RDX, and 34 ppbv for TNT were obtained. It was also demonstrated that the
presence of PETN residue within the range of 61 to 186 ng/cm2 can be detected at a given signal-to-background ratio of 10 using a few microjoules of laser energy. The technique also demonstrated
its potential for the direct analysis of trace explosive in soil. An LOD range of 0.5–4.3 ppm for PETN was established, which
is comparable to currently available techniques.
Figure Photofragmentation–chemiluminescence detector 相似文献
3.
Boguslaw Buszewski Pawel Olszowy Tomasz Ligor Malgorzata Szultka Jacek Nowaczyk Maciej Jaworski Marek Jackowski 《Analytical and bioanalytical chemistry》2010,397(1):173-179
Five adrenolytic drugs have been analyzed by liquid chromatography–mass spectrometry (LC–MS). Samples were prepared by solid-phase
microextraction (SPME) using polypyrrole fibers coated on stainless steel support as an adsorbent for the drugs. Adsorption
efficiencies were 95% and were close for all the drugs investigated. Relative standard deviations (RSD), calculated for samples
prepared in standard solutions, were in the range 2.5–13%, however RSD values for the drugs in human plasma were 2.5–4.5%.
Using LC–MS the limit of detection (LOD) and the limit of quantification (LOQ) were in the ranges 0.11–0.18 and 0.39–0.54 ng mL−1, respectively, for the five drugs. 相似文献
4.
Jennifer L. Gottfried Frank C. De Lucia Jr. Chase A. Munson Andrzej W. Miziolek 《Spectrochimica Acta Part B: Atomic Spectroscopy》2007,62(12):1405-1411
We have developed a double-pulse standoff laser-induced breakdown spectroscopy (ST-LIBS) system capable of detecting a variety of hazardous materials at tens of meters. The use of a double-pulse laser improves the sensitivity and selectivity of ST-LIBS, especially for the detection of energetic materials. In addition to various metallic and plastic materials, the system has been used to detect bulk explosives RDX and Composition-B, explosive residues, biological species such as the anthrax surrogate Bacillus subtilis, and chemical warfare simulants at 20 m. We have also demonstrated the discrimination of explosive residues from various interferents on an aluminum substrate. 相似文献
5.
V. H. Whitley D. E. Hooks K. J. Ramos J. F. O’Hara A. K. Azad A. J. Taylor J. Barber R. D. Averitt 《Analytical and bioanalytical chemistry》2009,395(2):315-322
The far infrared spectra of (100), (010), and (001)-oriented RDX single crystals were measured as the crystal was rotated
about the axis perpendicular to the polarization plane of the incident radiation. Absorption measurements were taken at temperatures
of both 20 K and 295 K for all rotations using terahertz time–domain spectroscopy. A number of discrete absorptions were found
ranging from 10–100 cm−1 (0.3–3 THz). The absorptions are highly dependent on the orientation of the terahertz polarization with respect to crystallographic
axes. 相似文献
6.
Square-wave voltammetry with the hanging drop mercury electrode as the working electrode was used for the determination of
ultratraces of explosives in aqueous solution. It was shown that the strong pressure dependence of the pneumatically controlled
multimode electrode system of a conventional Metrohm apparatus could be compensated by an additional pressure regulation,
through which the pressure variations could be decreased when switching from deaeration to the static measurements. By using
square-wave voltammetry with this electrode system after this modification the limits of detection for 2,4,6-trinitrotoluene
(TNT) and other TNT-metabolites could be decreased down to 0.2 μg L−1 when using a measurement time of 6 min. Also a simultaneous determination of TNT and hexahydro-1,3,5-trinitro-1,3,5-triazine
(RDX) was shown to be possible over a wide linear range and the detection limits then were 2.2 μg L−1 for TNT and 25 μg L−1 for RDX. By applying the highly stable and adjustable pressure as mentioned before, the calibrations could be kept stable
over a period of up to 1 week. 相似文献
7.
Fleroxacin is a third generation fluoroquinolone with broad spectrum antibacterial activity. In this work an LC-DAD method
for the analysis of fleroxacin was developed and validated using UV detection at 286 nm. The method was validated for linearity,
precision, robustness, LOD, LOQ, specificity and accuracy at concentrations of 0.2–20.0 μg mL−1 and r
2 = 1. The LOD and LOQ were 0.059 and 0.197 μg, respectively, the recoveries were 99.92–102.0% and the CV was less than 2.0%.
The LC-DAD validated method provided analytical sensitivity, specificity and reproducibility suitable for quality control
analysis. 相似文献
8.
Bradley Arnold Lisa Kelly Jeffrey B. Oleske Alexander Schill 《Analytical and bioanalytical chemistry》2009,395(2):349-355
A method of standoff detection based on the observation of laser-induced fluorescence–amplified spontaneous emission (LIF-ASE)
is described. LIF-ASE generates uniaxial intensity distributions of the observed fluorescence with the majority of intensity
propagating along the excitation axis in both the forward and backward directions. The detection of bulk vapor at significant
standoff distances is readily achieved. This method was used to detect NO directly and as a photoproduct after 213-nm excitation
of 2-, 3-, and 4-nitrotoluene. The NO LIF-ASE spectra were studied as a function of buffer gas. These studies showed that
the emission from different vibrational states was dependent upon the buffer gas used, suggesting that the populations of
vibrational states were influenced by the environment. A similar sensitivity of the vibrational populations was observed when
the different nitroaromatic precursors were used in nitrogen buffer gas. Such sensitivity to environmental influences can
be used to distinguish among the different nitroaromatic precursors and facilitate the identification of the bulk vapor of
these analytes. 相似文献
9.
On-site colorimetric methods are a valuable, cost-effective tool to assess the nature and extent of contamination in remediated sites and to enable on-site screening for police criminology laboratories. The existing colorimetric method for cyclotrimethylenetrinitramine (RDX) based on a Griess reaction suffers from the non-quantitative reduction to nitrite and from the unstable character of HNO2 in acidic medium. Thus we propose a novel spectrophotometric RDX assay in explosive mixtures and residues, based on (Zn + HCl) reduction of RDX in a microwave oven, followed by neutralization of the reduction products to ammonia and low molecular-weight amines, and Berthelot reaction of these amine-compounds with phenol and hypochlorite in alkaline medium to give an intensely blue indophenol dye absorbing at 631 nm. The molar absorptivity and limit of detection (LOD) for RDX were (1.08 ± 0.04) × 104 L mol−1 cm−1 and 0.18 mg L−1, respectively. Application of the method to synthetic mixture solutions of RDX and trinitrotoluene (TNT) at varying proportions showed that there was minimal interference from TNT (which could be compensated for by dicyclohexylamine colorimetry), since the Berthelot reaction was essentially non-responsive to m-substituted anilines derived from TNT upon (Zn + HCl) reduction. The proposed method was successfully applied to military-purpose explosive mixtures of (RDX + inert matter) such as Comp A5, Comp C4, and Hexal P30, and to (RDX + TNT) mixtures such as Comp B. The molar absorptivity of RDX was much higher than that of either ammonium or nitrate; RDX could be effectively separated from ammonium and nitrate in soil mixtures, based on solubility differences. The Berthelot method for RDX was statistically validated using Comp B mixtures against standard HPLC equipped with a Hypersil C-18 column with (40% MeOH-60% H2O) mobile phase, and against gas chromatography-thermal energy analysis (GC-TEA) system. 相似文献
10.
M. Pisarek P. Kędzierzawski M. Janik-Czachor K. J. Kurzydłowski 《Journal of Solid State Electrochemistry》2009,13(2):283-291
The stability of the passive film formed on austenitic 303 stainless steel in the as-received state and after severe plastic
deformation by hydrostatic extrusion (HE) leading to nanostructurization was investigated in an aggressive environment containing
Cl− ions by anodic polarization. Transmission electron microscopy (TEM) and stereological image analysis were used to examine
structural changes introduced by HE. Surface analytical techniques such as light microscopy, scanning electron microscopy,
Auger electron spectroscopy (AES), and scanning Auger microscopy (SAM) were used to characterize the morphology, grain size,
and chemistry of the surface, including local characterization of nonmetallic inclusions and their surface before and after
HE. SAM analysis revealed discontinuities of the passive oxide film on MnS inclusions. TEM and scanning transmission electron
microscopy examinations confirm a drastic reduction of grain size accompanied by a distinct refinement of the size of sulfide
inclusions in the HE matrix. These changes in the HE 303 stainless steel are apparently responsible for its reduced pitting
resistance compared to the as-received material.
Contribution to the Fall Meeting of the European Materials Research Society, Symposium D: 9th International Symposium on Electrochemical–Chemical
Reactivity of Metastable Materials, Warsaw, 17th–21st September, 2007. 相似文献
11.
Sara Wallin Anna Pettersson Henric Östmark Alison Hobro 《Analytical and bioanalytical chemistry》2009,395(2):259-274
A review of standoff detection technologies for explosives has been made. The review is focused on trace detection methods
(methods aiming to detect traces from handling explosives or the vapours surrounding an explosive charge due to the vapour
pressure of the explosive) rather than bulk detection methods (methods aiming to detect the bulk explosive charge). The requirements
for standoff detection technologies are discussed. The technologies discussed are mostly laser-based trace detection technologies,
such as laser-induced-breakdown spectroscopy, Raman spectroscopy, laser-induced-fluorescence spectroscopy and IR spectroscopy
but the bulk detection technologies millimetre wave imaging and terahertz spectroscopy are also discussed as a complement
to the laser-based methods. The review includes novel techniques, not yet tested in realistic environments, more mature technologies
which have been tested outdoors in realistic environments as well as the most mature millimetre wave imaging technique.
Figure Standoff detection and identification is one of the most wanted capabilities 相似文献
12.
A weak cation-exchange monolithic column has been prepared in stainless steel tubing and used as the solid-phase extraction
material in quantitative analysis of caffeine and theophylline in urine. Column switching, with water as mobile phase, was
used for on-line cleaning and screening of human urine samples. Reversed-phase high-performance liquid chromatography was
then performed on a C18 column with methanol–water 30:70 (v/v) as mobile phase at a flow rate of 0.5 mL min−1. Ultraviolet detection was performed at 274 nm. Good linear relationships were obtained between response and concentrations
of caffeine and theophylline in the range 0.1–50 μg mL−1. Absolute recovery ranged from 77.4 to 82.3% and inter-day and intra-day relative standard deviations were less than 5%.
The method was suitable for analysis of caffeine and theophylline in human urine, because it eliminated tedious pretreatment
and enabled rapid, economic, repeatable, and effective assay of traces of the drugs in biological samples. 相似文献
13.
Garg P Pardasani D Mazumder A Purohit A Dubey DK 《Analytical and bioanalytical chemistry》2011,399(2):955-963
The combination of dispersive solid-phase extraction (DSPE) and Fourier-transform infrared (FTIR) spectroscopy is presented
for detection and quantification of markers and simulants of nerve agents. Hydrophilic–lipophilic balance (HLB) sorbent was
used for extraction and enrichment of organophosphonates from water. When the extraction efficiency of DSPE was compared with
that of conventional solid-phase extraction (SPE), DSPE was more efficient. Extraction conditions such as extraction time,
and type and quantity of sorbent material were optimized. In DSPE, extracted analytes are detected and quantified on the sorbent
using FTIR as analytical technique. Absorbance in FTIR due to P–O–C stretching was used for detection and quantification.
Infrared absorbance of different analytes were compared by determining their molar absorptivities (ε
max). Quantitative analyses were performed employing modified Beer’s law, and relative standard deviations (RSDs) for intraday
repeatability and interday reproducibility were found to be in the range 0.30–0.90% and 0.10–0.80% respectively. The limit
of detection (LOD) was 5–10 μg mL−1. The applicability of the method was tested with an unknown sample prepared by mimicking the sample obtained in an international
official proficiency test. 相似文献
14.
Zhihua Yang Julius Pavlov Athula B. Attygalle 《Journal of mass spectrometry : JMS》2012,47(7):845-852
Helium Plasma Ionization (HePI) generates gaseous negative ions upon exposure of vapors emanating from organic nitro compounds. A simple adaptation converts any electrospray ionization source to a HePI source by passing helium through the sample delivery metal capillary held at a negative potential. Compared with the demands of other He‐requiring ambient pressure ionization sources, the consumption of helium by the HePI source is minimal (20–30 ml/min). Quantification experiments conducted by exposing solid deposits to a HePI source revealed that 1 ng of 2,4,6‐trinitrotoluene (TNT) on a filter paper (about 0.01 ng/mm2) could be detected by this method. When vapor emanating from a 1,3,5‐trinitroperhydro‐1,3,5‐triazine (RDX) sample was subjected to helium plasma ionization mass spectrometry (HePI‐MS), a peak was observed at m/z 268 for (RDX●NO2)?. This facile formation of NO2? adducts was noted without the need of any extra additives as dopants. Quantitative evaluations showed RDX detection by HePI‐MS to be linear over at least three orders of magnitude. TNT samples placed even 5 m away from the source were detected when the sample headspace vapor was swept by a stream of argon or nitrogen and delivered to the helium plasma ion source via a metal tube. Among the tubing materials investigated, stainless steel showed the best performance for sample delivery. A system with a copper tube, and air as the carrier gas, for example, failed to deliver any detectable amount of TNT to the source. In fact, passing over hot copper appears to be a practical way of removing TNT or other nitroaromatics from ambient air. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
15.
Scott D. Harvey Robert G. Ewing Melanie J. Waltman 《International Journal for Ion Mobility Spectrometry》2009,12(4):115-121
This study investigates the potential and limitations of a field-deployable analytical approach that involves selective capture
of explosive materials with direct analysis by ion mobility spectrometry (IMS). Selective capture of explosives was performed
on deactivated quartz fiber filters impregnated with metal β-diketonate polymers. These Lewis acidic polymers selectively
interact with Lewis base analytes such as explosives. The filters were directly inserted into an IMS instrument for analysis.
The uptake kinetics of 2,4,6-trinitrotoluene (TNT) from a saturated atmosphere were characterized, and based on these studies,
passive equilibrium sampling was applied to estimate the TNT concentration within an ammunition magazine that contained bulk
TNT. Hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) uptake from a saturated environment also was examined over a one-month
period. Each incremental sampling period showed increasing quantities of RDX culminating with collection of approximately
5 ng of RDX on the filter at the end of one month. This is the first time that gas-phase uptake of RDX has been demonstrated. 相似文献
16.
Preparation of magnetic molecularly imprinted polymer for rapid determination of bisphenol A in environmental water and milk samples 总被引:2,自引:0,他引:2
Yongsheng Ji Juanjuan Yin Zhigang Xu Chuande Zhao Huayu Huang Haixia Zhang Chunming Wang 《Analytical and bioanalytical chemistry》2009,395(4):1125-1133
A magnetic molecularly imprinted polymer (M-MIP) of bisphenol A (BPA) was prepared by miniemulsion polymerization. The morphological
and magnetic characteristics of the M-MIP were characterized by Fourier-transform infrared spectroscopy, transmission electron
microscopy, and vibrating sample magnetometry. The adsorption capacities of the M-MIP and the nonimprinted polymer were investigated
using static adsorption tests, and were found to be 390 and 270 mg g−1, respectively. Competitive recognition studies of the M-MIP were performed with BPA and the structurally similar compound
DES, and the M-MIP displayed high selectivity for BPA. A method based on molecularly imprinted solid-phase extraction assisted
by magnetic separation was developed to extract BPA from environmental water and milk samples. Various parameters such as
the mass of sorbent, the pH of the sample, the extraction time, and desorption conditions were optimized. Under selected conditions,
extraction was completed in 15 min. High-performance liquid chromatography with UV detection was employed to determine BPA
after the extraction. For water samples, the developed method exhibited a limit of detection (LOD) of 14 ng L−1, a relative standard deviation of 2.7% (intraday), and spiked recoveries ranging from 89% to 106%. For milk samples, the
LOD was 0.16 μg L−1, recoveries ranged from 95% to 101%, and BPA was found in four samples at levels of 0.45–0.94 μg L−1. The proposed method not only provides a rapid and reliable analysis but it also overcomes problems with conventional solid-phase
extraction (SPE), such as the packing of the SPE column and the time-consuming nature of the process of loading large-volume
samples. 相似文献
17.
Quarles CD Carado AJ Barinaga CJ Koppenaal DW Marcus RK 《Analytical and bioanalytical chemistry》2012,402(1):261-268
A new, low-power ionization source for the elemental analysis of aqueous solutions has recently been described. The liquid
sampling–atmospheric pressure glow discharge (LS-APGD) source operates at relatively low currents (<20 mA) and solution flow
rates (<50 μL min−1), yielding a relatively simple alternative for atomic mass spectrometry applications. The LS-APGD has been interfaced to
what is otherwise an organic, LC-MS mass analyzer, the Thermo Scientific Exactive Orbitrap without any modifications, other
than removing the electrospray ionization source supplied with that instrument. A glow discharge is initiated between the
surface of the test solution exiting a glass capillary and a metallic counter electrode mounted at a 90° angle and separated
by a distance of ~5 mm. As with any plasma-based ionization source, there are key discharge operation and ion sampling parameters
that affect the intensity and composition of the derived mass spectra, including signal-to-background ratios. We describe
here a preliminary parametric evaluation of the roles of discharge current, solution flow rate, argon sheath gas flow rate,
and ion sampling distance as they apply on this mass analyzer system. A cursive evaluation of potential matrix effects due
to the presence of easily ionized elements indicate that sodium concentrations of up to 50 μg mL−1 generally cause suppressions of less than 50%, dependant upon the analyte species. Based on the results of this series of
studies, preliminary limits of detection (LOD) have been established through the generation of calibration functions. While
solution-based concentration LOD levels of 0.02–2 μg mL−1 are not impressive on the surface, the fact that they are determined via discrete 5 μL injections leads to mass-based detection
limits at picogram to single-nanogram levels. The overhead costs associated with source operation (10 W d.c. power, solution
flow rates of <50 μL min−1, and gas flow rates <10 mL min−1) are very attractive. While further optimization in the source design is suggested here, it is believed that the LS-APGD
ion source may present a practical alternative to inductively coupled plasma sources typically employed in elemental mass
spectrometry. 相似文献
18.
S. V. Ingale P. B. Wagh A. K. Tripathi A. S. Dudwadkar S. S. Gamre P. T. Rao I. K. Singh Satish C. Gupta 《Journal of Sol-Gel Science and Technology》2011,58(3):682-688
The degradation of nitro aromatics like trinitrotoluene (TNT) released in the waste water from explosive process plants is
the serious problem due to toxic and explosive nature of TNT. The poor response of TNT to biodegradation enhanced the gravity
of the problem. We have demonstrated that high specific surface area TiO2–SiO2 nano-composite aerogel is promising photo catalyst in successful treating of TNT contaminated aqueous solution. The TiO2–SiO2 composite aerogel with nominal content of 20 and 50% TiO2, used as catalyst, were prepared by co-precursor sol–gel method using titanium isopropaxide and tetramethylorthosilicate
as source of titania and silica, respectively. The XRD studies confirmed formation of anatase phase of crystalline TiO2 with nano sized crystallites. The TiO2–SiO2 aerogel showed specific surface area of 1,107 and 485 m2/g for the aerogels containing 20 and 50% TiO2, respectively. The 100 ppm TNT solution was treated, in 700 ml capacity reaction vessel, using H2O2 oxidizer and TiO2–SiO2 aerogel catalyst in presence of UV light (8 W UV lamp). Using TiO2–SiO2 (50/50) aerogel with surface area of 485 m2/g, we succeeded to reduce the TOC to 1 ppm within 3.5 h where as using TiO2/SiO2 (20/80) aerogel with surface area of 1,107 m2/g, the TOC was reduced to about only 7 ppm in the same time. It revealed that the combination of high TiO2 content and high specific surface area is an important factor to achieve effective and faster degradation of TNT for complete
mineralization. 相似文献
19.
Laczka O Baldrich E del Campo FJ Muñoz FX 《Analytical and bioanalytical chemistry》2008,391(8):2825-2835
Functionalisation of the sensing surface is a key factor in immunosensor fabrication as it allows target-selective capture
and prevents nonspecific adsorption of undesired components. Gold immunofunctionalisation using self-assembled monolayers
(SAM) has been widely exploited to this end for the detection of small targets. However, we recently demonstrated that this
strategy fails when detecting whole bacteria cells (Baldrich et al., Anal Bioanal Chem 390:1557–1562, 2008). We now investigate different physisorption-based alternatives using E. coli as the target organism. Our results demonstrate that physisorption generates the appropriate substrate for the specific detection
of bacteria on gold surfaces, providing detection limits down to 105 cells mL−1 in an ELISA-type colorimetric assay. Additionally, surface coverage is highly reproducible when assayed by impedance spectroscopy
and the inter- and intra-assay coefficients of variation are below 10–15% in all cases. These surfaces were stable, retained
functionality and did not suffer from significant biomolecule desorption after 10 days storage in PBS at 37 °C, hence confirming
physisorption as a cheap, simple and efficient strategy for the detection of bacteria. 相似文献
20.
Summary A rapid and simple method has been developed for determination of imidazolinone (IMI) residues in soil.
Extraction of the analytes from the soil matrix was performed with a pressurized-liquid-extraction apparatus built in this
laboratory. Four different types of soil sample (clay, clay loam, sandy clay loam, and silty loam) were fortified with target
compounds at levels of 10 and 50 ng g−1 by a procedure which can mimic weathered soils. The samples were then dried and packed in a 25 cm×4.6 mm i. d. stainless
steel column; this was placed inside a GC oven and extracted by passing an aqueous solution of KCl (0.1m, 20 mL) through the column at 90°C.
Quantification of the analytes in the final extract (50-μL injection) was performed by reversed-phase liquid chromatography-mass
spectrometry with a TurbolonSpray interface. Recoveries of the analytes were greater than 83% andRSD less than 7%. The method detection limit was in the 1–2.5ng g−1 range in analysis by time-scheduled selected-ion monitoring (SIM). 相似文献