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1.
Ma X Zhu T Xu H Li G Zheng J Liu A Zhang J Du H 《Analytical and bioanalytical chemistry》2008,390(4):1133-1137
A chemical prototype sensor was constructed based on nanofiber-structured TiO2 and highly sensitive quartz resonators. The gas-sensing behavior of this new sensor to selected simulant warfare agents was
investigated at room temperature. Results showed rapid response and good reversibility of this sensor when used with high-purity
nitrogen. This provides a simple approach to preparation of materials needed as chemical sensors for selected organic volatiles
or warfare agents.
Figure Sensing behavior of TiO2 nanofiber sensor to chemical vapors 相似文献
2.
Webb A 《Analytical and bioanalytical chemistry》2007,388(3):525-528
Figure Schematic diagram of a typical arrangement used for hyphenating chemical microseparations (e.g. capillary HPLC, CE, or CEC)
with microcoil NMR detection 相似文献
3.
Inagaki K Narukawa T Yarita T Takatsu A Okamoto K Chiba K 《Analytical and bioanalytical chemistry》2007,389(3):691-696
A coprecipitation method using sample constituents as carrier precipitants was developed that can remove molybdenum, which
interferes with the determination of cadmium in grain samples via isotope dilution inductively coupled plasma mass spectrometry
(ID-ICPMS). Samples were digested with HNO3, HF, and HClO4, and then purified 6 M sodium hydroxide solution was added to generate colloidal hydrolysis compounds, mainly magnesium hydroxide.
Cadmium can be effectively separated from molybdenum because the cadmium forms hydroxides and adsorbs onto and/or is occluded
in the colloid, while the molybdenum does not form hydroxides or adsorb onto the hydrolysis colloid. The colloid was separated
by centrifugation and then dissolved with 0.2 M HNO3 solution to recover the cadmium. The recovery of Cd achieved using the coprecipitation was >97%, and the removal efficiency
of Mo was approximately 99.9%. An extremely low procedural blank (below the detection limit of ICPMS) was achieved by purifying
the 6 M sodium hydroxide solution via Mg coprecipitation using Mg(NO3)2 solution. The proposed method was applied to two certified reference materials (NIST SRM 1567a wheat flour and SRM 1568a
rice flour) and CCQM-P64 soybean powder. Good analytical results with small uncertainties were obtained for all samples. This
method is simple and reliable for the determination of Cd in grain samples by ID-ICPMS.
Figure Overview of a coprecipitation method using sample constituents 相似文献
4.
Herschbach H Hosomizu K Hahn U Leize E Van Dorsselaer A Imahori H Nierengarten JF 《Analytical and bioanalytical chemistry》2006,386(1):46-51
The electrospray mass spectrometric characterization of neutral dendrons with a carboxylic acid function or a t-butyl ester moiety at the central point and up to eight peripheral C60 subunits has been performed and is described in detail. Molecules bearing a carboxylic acid group at the center turned out
to be preferentially ionized by deprotonation, whereas those with a t-butyl ester head group were ionized by reduction of the C60 units in the infusion capillary of the electrospray source.
Electronic supplementary material Supplementary material is available for this article at and is accessible for authorized users. 相似文献
5.
Martens T Bogaerts A Brok W van Dijk J 《Analytical and bioanalytical chemistry》2007,388(8):1583-1594
A model developed for a dielectric barrier discharge (DBD) in helium, used as a new spectroscopic source in analytical chemistry,
is presented in this paper. The model is based on the fluid approach and describes the behavior of electrons, He+ and ions, He metastable atoms, He atoms in higher excited levels, and He2 dimers. The He ground-state atoms are regarded as background gas. The characteristic effect of charging/discharging of the
dielectrics which cover both electrodes is also simulated. Typical results of the model include the distribution of potential
inside the plasma (and the potential drop across the dielectrics), the electric current and gap voltage as a function of time
for a given applied potential profile, the spatial and temporal number-density profiles of the different plasma species, and
the relative contributions of the mechanisms of their production and loss.
Figure Schematic diagram of the dielectric barrier discharge (left) and typical temporal profiles of voltage and current, as obtained
from the simulations (right) 相似文献
6.
Various toxicological and metabolic interactions have been reported to exist between arsenic and selenium. In the present
study, synthetic seleno-arsenic compounds, potentially suitable for probing metabolic interactions between these two elements,
were prepared and tentatively characterized by using high-performance liquid chromatography (HPLC)–electrospray tandem mass
spectrometry and HPLC–inductively coupled plasma mass spectrometry. In analogy to the recently identified thio-arsenic species,
which can be prepared from their corresponding oxo-arsenic species via reaction with H2S, the seleno-arsenic compounds were also derived from oxo-arsenic compounds via reaction with H2Se.
Figure H2Se bubbled into solutions containing oxo‐arsenosugars converts them into their seleno‐arsenosugar analogues. 相似文献
7.
An impurity-profiling method for 3,4-methylenedioxymethamphetamine (MDMA) is presented. The impurities of interest were extracted
by solid-phase extraction (SPE) on Bakerbond C18 spe columns from a weakly alkaline solution (pH 8.5). Development of the extraction conditions covered selection of the buffer
for dissolution of the sample and the volume of the eluent used to elute the impurities. An important part of the studies
was to optimise the separation conditions, and the simplex method was used for this purpose. Cluster analysis was applied
for comparison of samples and its grouping. The developed method was based on the areas of 33 selected peaks corresponding
to MDMA impurities. All examined samples were correctly classified into clusters corresponding to the synthetic route.
相似文献
8.
Lieberzeit PA Afzal A Glanzing G Dickert FL 《Analytical and bioanalytical chemistry》2007,389(2):441-446
Titanate sol–gel layers imprinted with midchain carbonic acids have proven highly useful for detecting engine oil degradation
processes owing to selective incorporation of oxidised base oil components. Synthesising the material from TiCl4 in CCl4 and precipitating with water leads to imprinted TiO2 nanoparticles with a diameter of 200–300 nm. Replacing the water by a 1 M ammonium hydroxide solution reduces the average
particle size to 50–100 nm with retention of the interaction capabilities. Experiments with the latter solution revealed that
the 100-nm particles take up substantially more analyte, indicating a size-dependent phenomenon. As the number of interaction
sites within each material is the same, this cannot be a consequence of thermodynamics but must be one of accessibility. The
sensor characteristic of water-precipitated particles towards engine oil degradation products shows substantially increased
sensitivity and dynamic range compared with the corresponding thin films. Coating quartz crystal microbalances with such nanoparticle
materials leads to engine oil degradation sensors owing to incorporation of acidic base oil oxidation products. Interaction
studies over a large range of layer thicknesses revealed that both the absolute signal and the steepness of the correlation
between the sensor signal and the layer height is 2 times higher for the particles.
Figure Generation of molecularly imprinted sol–gel nanoparticles 相似文献
9.
Surmeian A Diplasu C Groza A Ganciu M Belenguer P Tempez A Chapon P 《Analytical and bioanalytical chemistry》2007,388(8):1625-1629
A high-current pulsed hollow cathode discharge was used to study the role of atomic and ionic metastables involved in ionization
plasma processes. We observed the enhancement of the spectral emission lines of noble gas ions in the afterglow. A study of
the processes that involve atomic and ionic metastables is of great interest since it should lead to a better understanding
of and enhanced control over the ionization mechanisms crucial to analytical glow discharge mass spectrometry (GDMS) analysis.
Figure Time profile of Ti, Ti+, and Ne+ spectral lines 相似文献
10.
A new vapor generation system for mercury (Hg) species based on the irradiation of mercaptoethanol (ME) with UV was developed
to provide an effective sample introduction unit for atomic fluorescence spectrometry (AFS). Preliminary investigations of
the mechanism of this novel vapor generation system were based on GC–MS and FT–IR studies. Under optimum conditions, the limits
of determination for inorganic divalence mercury and methyl mercury were 60 and 50 pg mL−1, respectively. Certified reference materials (BCR 463 tuna fish and BCR 580 estuarine sediment) were used to validate this
new method, and the results agreed well with certified values. This new system provides an attractive alternative method of
chemical vapor generation (CVG) of mercury species compared to other developed CVG systems (for example, the traditional KBH4/NaOH–acid system). To our knowledge, this is the first systematic report on UV/ME-based Hg species vapor generation and the
determination of total and methyl Hg in environmental and biological samples using UV/ME–AFS.
Figure A new vapor generation system for mercury species using mercaptoethanol under UV irradiation was developed as an effective
sample introduction unit for atomic fluorescence spectrometry 相似文献
11.
Klejdus B Vacek J Benesová L Kopecký J Lapcík O Kubán V 《Analytical and bioanalytical chemistry》2007,389(7-8):2277-2285
A rapid-resolution HPLC/UV-VIS DAD separation method (which takes <1 min) for the determination and identification of genistin,
genistein, daidzein, daidzin, glycitin, glycitein, ononin, formononetin, sissotrin and biochanin A in fmol quantities in submicroliter
sample volumes was optimized. A linear gradient elution (0 min 22% B, 1.0 min 80% B, 1.4 min 100% B, 1.8 min 22% B) using
a mobile phase containing 0.2 % (v/v) acetic acid (solvent A) and methanol (solvent B) was applied on a Zorbax SB C18 column (1.8 μm particle size) at 80 °C. The method was verified using samples of bits of soy and methanolic extracts from
Trifolium pratense, Iresine herbstii and Ononis spinosa plants. Pseudobaptigenin glucoside, irilone, prunetin, texasin, tlatlancuayin and other isoflavones, in addition to aglycones
of isoflavones and their β-glucosides and malonyl and acetyl derivatives, were identified by UV-VIS DAD and electrospray mass
spectrometric (ESI-MS) detection in the extracts.
Figure Rapid resolution HPLC for determination and identification of isoflavones in soy preparations and plant extracts 相似文献
12.
Natalini B Sardella R Camaioni E Gioiello A Pellicciari R 《Analytical and bioanalytical chemistry》2007,388(8):1681-1688
The discovery that bile acids are involved in the modulation of nuclear steroid receptors has prompted renewed interest in
this field of research. Due to the nature of research in this field, a technique that enables simple and effective assessment
of the hydrophobic/hydrophilic balance, thus improving and speeding up evaluations of the biological profiles of these compounds,
is greatly needed. In this context, both CMC value determination and RP-HPLC mobility evaluation were explored as possible
approaches. While the CMC was calculated using the noninvasive conductimetric method, the RP-HPLC mobility was assessed by
measuring the retention factor at several mobile phase compositions and extrapolating back to the pure aqueous mobile phase.
The correlation of the CMC with the derived chromatographic hydrophobic index ϕ
0 was satisfactory.
Figure Experimental versus predicted pCMC values 相似文献
13.
Henchoz Y Schappler J Geiser L Prat J Carrupt PA Veuthey JL 《Analytical and bioanalytical chemistry》2007,389(6):1869-1878
A rapid and universal capillary zone electrophoresis (CZE) method was developed to determine the dissociation constants (pK
a) of the 20 standard proteogenic amino acids. Since some amino acids are poorly detected by UV, capacitively coupled contactless
conductivity detection (C4D) was used as an additional detection mode. The C4D coupling proved to be very successful on a conventional CE-UV instrument, neither inducing supplementary analyses nor instrument
modification. In order to reduce the analysis time for pK
a determination, two strategies were applied: (i) a short-end injection to reduce the effective length, and (ii) a dynamic
coating procedure to generate a large electroosmotic flow (EOF), even at pH values as low as 1.5. As a result, the analysis
time per amino acid was less than 2 h, using 22 optimized buffers covering a pH range from 1.5 to 12.0 at a constant ionic
strength of 50 mM. pK
a values were calculated using an appropriate mathematical model describing the relationship between effective mobility and
pH. The obtained pK
a values were in accordance with the literature.
Figure
a UV (1) and C4D (2) detectors placed on-line on the CE capillary. b Curve of effective mobility as a function of pH for histidine 相似文献
14.
We screened a series of RNA and DNA aptamers for their ability to serve in the dye displacement assays in which analytes compete
with TO dye. We conclude that, while the performance of the TO dye displacement approach is not always predictable, it is
still a simple and sensitive assay to detect binding between RNA aptamers and small molecules. In particular, we describe
efficient assays for tobramycin and theophylline, with up to 90% displacement of TO observed, and we describe the first aptameric
assay for cAMP.
Figure An RNA or DNA aptamer against a molecule (circle) binds TO dye, resulting in a fluorescent complex. Presence of free molecule in solution results in the displacement of TO
from the complex and a reduction in fluorescence
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
15.
Mismatch binding molecules (MBLs), strongly and selectively bound to the mismatched base pair in duplex DNA, were immobilized
on Sepharose. Three MBL–Sepharose columns were prepared with three MBLs, naphthyridine dimer (ND), naphthyridine–azaquinolone (NA), and aminonaphthyridine dimer (amND), which exhibited different binding profiles to the mismatched base pairs. These three MBL–Sepharose columns showed characteristic
elution profiles for DNA duplexes containing mismatched base pairs. The ND–Sepharose column separated the G–G and G–A mismatched DNA from fully matched duplexes. The NA–Sepharose column separated the A–A and G–A mismatched DNA from other DNA duplexes. The amND–Sepharose column separated the C–C mismatched DNA. These chromatographic profiles were very consistent with the binding preference
of each MBL. By changing the elution conditions from sodium hydroxide to sodium chloride, MBL–Sepharose columns were also
able to separate the mismatched DNA that weakly bound to the MBL from fully matched DNA duplex.
Figure MBL-Sepharose affinity chromatography successfully separates the mismatched duplex DNA from fully matched duplex. 相似文献
16.
In the past 20 years the characterization of electroactive surfaces and electrode reactions by scanning probe techniques has
advanced significantly, benefiting from instrumental and methodological developments in the field. Electrochemical and electrical
analysis instruments are attractive tools for identifying regions of different electrochemical properties and chemical reactivity
and contribute to the advancement of molecular electronics. Besides their function as a surface analytical device, they have
proved to be unique tools for local synthesis of polymers, metal depots, clusters, etc. This review will focus primarily on
progress made by use of scanning electrochemical microscopy (SECM), conductive AFM (C-AFM), electrochemical scanning tunneling
microscopy (EC-STM), and surface potential measurements, for example Kelvin probe force microscopy (KFM), for multidimensional
imaging of potential-dependent processes on metals and electrified surfaces modified with polymers and self assembled monolayers.
Figure Electrochemical and electrical tools like scanning electrochemical microscopy, conductive atomic force microscopy, electrochemical
scannig tunneling microscopy and Kelvin probe force microscopy (see figure) are powerful tools for the multidimensional imaging
of potential-dependent processes on metals and electrified surfaces modified with polymers and self assembled monolayers. 相似文献
17.
18.
Melphalan is a bifunctional alkylating agent that covalently binds to the nucleophilic sites present in DNA. In this study
we investigated oligonucleotides prepared enzymatically from DNA modified with melphalan. Calf thymus DNA was incubated in-vitro
with melphalan and the resulting modifications were enzymatically cleaved by means of benzonase and nuclease S1. Efficient
sample preconcentration was achieved by solid-phase extraction, in which phenyl phase cartridges resulted in better recovery
of the modified species than C18. The applied enzymatic digestion time resulted in production of trinucleotide adducts which were efficiently separated and
detected by use of reversed-phase HPLC coupled to an ion-trap mass spectrometer with electrospray ionization. It was assumed
that melphalan could act as both a monofunctional and bifunctional alkylating agent. Mono-alkylated adducts were much more
abundant, however, and the alkylation site was located on the nucleobases. On the other hand, we unequivocally identified
cross-link formation in DNA, even though at low abundance and only a few adduct types were detected.
Figure Different Alkylation reactions of Melphalan with DNA 相似文献
19.
20.
Limbut W Hedström M Thavarungkul P Kanatharana P Mattiasson B 《Analytical and bioanalytical chemistry》2007,389(2):517-525
A capacitive biosensor for the detection of bacterial endotoxin has been developed. Endotoxin-neutralizing protein derived
from American horseshoe crab was immobilized to a self-assembled thiol layer on a biosensor transducer (Au). Upon injection
of a sample containing endotoxin, a decrease in the observed capacitive signal was registered. Endotoxin could be determined
under optimum conditions with a detection limit of 1.0 × 10−13 M and linearity ranging from 1.0 × 10−13 to 1.0 × 10−10 M. Good agreement was achieved when applying endotoxin preparations purified from an Escherichia coli cultivation to the capacitive biosensor system, utilizing the conventional method for quantitative endotoxin determination,
the Limulus amebocyte lysate test as a reference. The capacitive biosensor method was statistically tested with the Wilcoxon signed rank test, which proved
the system is acceptable for the quantitative analysis of bacterial endotoxin (P < 0.05).
Figure The flow-injection capacitive biosensor system and the capacitive properties of the transducer surface, where CSAM is the capacitance change of the self-assembled thiol monolayer, CP is the capacitance change of the protein layer, Ca is the capacitance change of the analyte layer and CTotal is the total capacitance change measured at the working electrode/solution interface (modified from Limbut et al., 2006.
Biosens Bioelectron 22: 233-240) 相似文献