共查询到20条相似文献,搜索用时 31 毫秒
1.
Núria Serrano José Manuel Díaz-Cruz Cristina Ariño Miquel Esteban 《Analytical and bioanalytical chemistry》2010,396(3):1365-1369
A commercially available screen-printed carbon electrode coated with an ex situ deposited bismuth film (BiSPCE) has been applied
to the determination of Pb(II) and Zn(II) ions in tap water (Barcelona water distribution network) by means of stripping voltammetry
(SV) and stripping chronopotentiometry (SCP). A good reproducibility of the measurements and a satisfactory agreement between
SV and SCP data were observed for both heavy metal ions. Although, in principle, the procedure could be also suited to the
determination of Cd(II), this species was not detected. The results were also consistent with the routine ICP-OES measurements
of the water distribution company, thus confirming the potential usefulness of such BiSPCE disposable devices for the analysis
of heavy metals in natural waters.
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2.
Bo Yan Zheng-Jiang Zhu Oscar R. Miranda Apiwat Chompoosor Vincent M. Rotello Richard W. Vachet 《Analytical and bioanalytical chemistry》2010,396(3):1025-1035
Monolayer-protected gold nanoparticles (AuNPs) feature unique surface properties that enable numerous applications. Thus,
there is a need for simple, rapid, and accurate methods to confirm the surface structures of these materials. Here, we describe
how laser desorption/ionization mass spectrometry (LDI-MS) can be used to characterize AuNPs with neutral, positively, and
negatively charged surface functional groups. LDI readily desorbs and ionizes the gold-bound ligands to produce both free
thiols and disulfide ions in pure and complex samples. We also find that LDI-MS can provide a semi-quantitative measure of
the ligand composition of mixed-monolayer AuNPs by monitoring mixed disulfide ions that are formed. Overall, the LDI-MS approach
requires very little sample, provides an accurate measure of the surface ligands, and can be used to monitor AuNPs in complex
mixtures.
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3.
Zhao Yue Waqas Khalid Marco Zanella Azhar Zahoor Abbasi Andrea Pfreundt Pilar Rivera Gil Kirsten Schubert Fred Lisdat Wolfgang J. Parak 《Analytical and bioanalytical chemistry》2010,396(3):1095-1103
Gold electrodes with switchable conductance are created by coating the gold surface with different colloidal quantum dots.
For the quantum dot immobilization, a dithiol compound was used. By polarizing the electrode and applying a light pointer,
local photocurrents were generated. The performance of this setup was characterized for a variety of different nanoparticle
materials regarding drift and signal-to-noise ratio. We varied the following parameters: quantum dot materials and immobilization
protocol. The results indicate that the performance of the sensor strongly depends on how the quantum dots are bound to the
gold electrode. The best results were obtained by inclusion of an additional polyelectrolyte film, which had been fabricated
using layer-by-layer assembly.
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4.
Solution-enhanced dispersion by supercritical fluids (SEDS) was applied to produce nano-sized recombinant human growth hormone
(hGH) particles. Ethanol was used to help the supercritical carbon dioxide to extract water from the aqueous protein solution.
Various sizes of hGH nanoparticles were successfully prepared with a narrow particle size distribution from aqueous ethanol
solution without using any additive. The theoretical particle sizes were deduced from the calculated droplet sizes based on
a modified Jasuja’s equation. The calculated mean particle sizes and the experimentally obtained ones were compared and the
results showed an excellent correlation coefficient (R
2) of 0.995.
Figure Distribution of hGH Nano-particles 相似文献
5.
Ice chromatography, in which water-ice particles are employed as a chromatographic stationary phase, has proven an efficient
technique for probing the solution/ice interface. The preparation of fine ice particles has allowed us to not only obtain
higher-resolution separation but also investigate the molecular processes occurring on the ice surface in more detail. Chromatographic
investigations have revealed that two or more hydrogen bonds are simultaneously formed between a solute and the dangling bonds
on the ice surface when the solute gives measurable retention. Several compounds, including estrogens, amino acids, and acyclic
polyethers, have been successfully separated by ice chromatography with a hexane-based mobile phase. In addition, this method
effectively probes the surface melting of the ice stationary phase and the liquid phase that coexists with water ice at thermodynamic
equilibrium. The thickness of the surface liquid layer and the size of the liquid phase that grows inside an ice particle
have been evaluated. The perspectives of this method are also discussed.
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6.
Rudolf Tuckermann Ljiljana Puskar Mahta Zavabeti Ryo Sekine Don McNaughton 《Analytical and bioanalytical chemistry》2009,394(5):1433-1441
An experimental apparatus combining Raman spectroscopy with acoustic levitation, Raman acoustic levitation spectroscopy (RALS),
is investigated in the field of physical and chemical analytics. Whereas acoustic levitation enables the contactless handling
of microsized samples, Raman spectroscopy offers the advantage of a noninvasive method without complex sample preparation.
After carrying out some systematic tests to probe the sensitivity of the technique to drop size, shape, and position, RALS
has been successfully applied in monitoring sample dilution and preconcentration, evaporation, crystallization, an acid–base
reaction, and analytes in a surface-enhanced Raman spectroscopy colloidal suspension.
Figure We have systematically investigated the analytical potential of Raman spectroscopy of samples in acoustically levitated drops. 相似文献
7.
Blo G Ceccarini A Conato C Contado C Fagioli F Fuoco R Pagnoni A Dondi F 《Analytical and bioanalytical chemistry》2006,384(4):922-930
Direct hyphenation of electrothermal atomic-absorption spectroscopy (ETAAS) to sedimentation field-flow fractionation (SdFFF)
has been developed to enable elemental characterization of submicron particles as a function of size. This hyphenation is
particularly suitable for characterizing colloidal particles of environmental interest, for example water-borne particles.
The interface is an automatic capillary injection device (CID) which enables direct introduction of large and variable volumes
of colloidal particle suspensions into a hot graphite furnace, thus preconcentrating the colloidal particles on the furnace
walls. The method was validated by determination of Fe in certified submicron Fe2O3. The procedure was set up by first optimizing the SdFFF fractionation under programmed field conditions, thus enabling optimum
fractionation of particle size. The ETAAS procedure was then tested to determine whether it could be used for direct analysis
of Fe2O3 slurries without the need for a mineralization step. CID coupled to ETAAS was subsequently exploited for its ability to enhance
the sensitivity, because of the increased injection volume. Statistical tests and data handling were conducted to prove the
suitability of the ETAAS-CID module. Finally, off-line and on-line ETAAS-CID-SdFFF hyphenation were investigated. These experiments
emphasized the advantages of the on-line coupling, because it enables synchronized sampling, enrichment, and elemental analysis
of the flowing eluate. The benefits of the proposed hyphenation are the high specificity of analytical detection, increased
sensitivity, reduction of analysis time, and minimum sample handling and contamination.
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8.
On-line NMR detection of microgram quantities of heparin-derived oligosaccharides and their structure elucidation by microcoil NMR 总被引:1,自引:0,他引:1
The isolation and purification of sufficient quantities of heparin-derived oligosaccharides for characterization by NMR is
a tedious and time-consuming process. In addition, the structural complexity and microheterogeneity of heparin makes its characterization
a challenging task. The improved mass-sensitivity of microcoil NMR probe technology makes this technique well suited for characterization
of mass-limited heparin-derived oligosaccharides. Although microcoil probes have poorer concentration sensitivity than conventional
NMR probes, this limitation can be overcome by coupling capillary isotachophoresis (cITP) with on-line microcoil NMR detection
(cITP-NMR). Strategies to improve the sensitivity of on-line NMR detection through changes in probe design and in the cITP-NMR
experimental protocol are discussed. These improvements in sensitivity allow acquisition of cITP-NMR survey spectra facilitating
tentative identification of unknown oligosaccharides. Complete structure elucidation for microgram quantities of the purified
material can be carried out through acquisition of 2D NMR spectra using a CapNMR microcoil probe.
Survey NMR spectrum obtained by cITP-NMR using a second-generation probe (the microcoil of which is shown) facilitates tentative
identification of unknown oligosaccharides (e.g., the heparin-derived tetrasaccharide illustrated) 相似文献
9.
Emily O’Neill Danielle Harrington John Allison 《Analytical and bioanalytical chemistry》2009,393(8):2029-2038
Monitoring of cell cultures in microbioreactors is a crucial task in cell bioassays and toxicological tests. In this work
a novel tool based on a miniaturized sensor array fabricated using low-temperature cofired ceramics (LTCC) technology is presented.
The developed device is applied to the monitoring of cell-culture media change, detection of the growth of various species,
and in toxicological studies performed with the use of cells. Noninvasive monitoring performed with the LTCC microelectrode
array can be applied for future cell-engineering purposes.
Figure Microelectrode array for monitoring of cell cultures 相似文献
10.
Isaac Stayton Jeffrey Winiarz Katie Shannon Yinfa Ma 《Analytical and bioanalytical chemistry》2009,394(6):1595-1608
The toxicology of nanomaterials is a blooming field of study, yet it is difficult to keep pace with the innovations in new
materials and material applications. Those applications are quickly being introduced in research, industrial, and consumer
settings. Even though the cytotoxicity of many types of nanoparticles has been demonstrated, the behavior of those particles
in a biological environment is not yet fully known. This work characterized the following over time: protein adsorption on
silica particle surfaces, the internalization of particles in human lung carcinoma (A549) cells when coated with different
specific proteins or no proteins at all, and the cellular loss of particles following the removal of extracellular particles.
Proteins were shown to quickly saturate the particle surface, followed by a competitive process of particle agglomeration
and protein adsorption. Uptake of particles peaked at 8–10 h, and it was determined that, in this system, the charge of the
protein-coated particles changed the rate of uptake if the charge difference was great enough. Cells internalized particles
lacking any adsorbed proteins with approximately 3 times the rate of protein-coated particles with the same charge. Although
particles exited cells over time, the process was slower than uptake and did not near completion within 24 h. Finally, analysis
at the single cell level afforded observations of particle agglomerates loosely associated with cell membranes when serum
was present in the culture medium, but in the absence of serum, particles adhered to the dish floor and formed smaller agglomerates
on cell surfaces. Although data trends were easily distinguished, all samples showed considerable variation from cell to cell.
Figure Silica-capped fluorescent semiconductor nanoparticles as internalized by human lung epithelial cells and adsorbed to a glass
substrate in protein-free culture medium. 相似文献
11.
Manfred P?hlein Raquel Urpi Bertran Marion Wolf Rudi van Eldik 《Analytical and bioanalytical chemistry》2009,394(2):583-595
Reference materials for the analysis of polybrominated diphenyl ethers, polybrominated biphenyls and other common brominated
flame retardants (FR) in styrenic polymers were prepared to suit the demands of actual restriction of the use of certain hazardous
substances in electrical and electronic equipment analytics. Three methods of preparation were employed, viz. pellet forming,
dissolution/vaporisation and extrusion, whereby extrusion proved to be the most suitable method. For extrusion, three procedures
of pre-mixing were investigated: the polymers were either mixed with FR powder, FR solutions or FR concentrates that were
taken from waste industrial polymers. The latter procedure proved to be most appropriate in terms of analyte concentration,
predictability and recovery. The homogeneity of the samples, as well as the chemical and thermal long-term stabilities, was
investigated. The result was an optimised method to prepare a suitable reference material for laboratory use.
Figure
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
12.
We quantitatively modeled the volume phase transition of a hydrogel containing a crystalline colloidal array with a crown
ether ligand which binds Pb2+. The hydrogel volume response and the wavelength diffracted depend on the Pb2+ concentration and on both the ionic strength and the valence of the nonbinding ionic species. We successfully modeled the
response of this hydrogel Pb2+ sensor to ionic strength and the cation valence of the added salts.
Figure Cation identity dependence of crown ether photonic crystal Pb+ sensing 相似文献
13.
Development and certification of the new NIES CRM 28: urban aerosols for the determination of multielements 总被引:1,自引:0,他引:1
Mori I Sun Z Ukachi M Nagano K McLeod CW Cox AG Nishikawa M 《Analytical and bioanalytical chemistry》2008,391(6):1997-2003
A new environmental certified reference material (CRM) for the determination of multielements in aerosol particulate matter
has been developed and certified by the National Institute for Environmental Studies (NIES), Japan, based on analyses by a
network of laboratories using a wide range of methods. The origin of the material was atmospheric particulate matter collected
on filters in a central ventilating system in a building in Beijing city centre. The homogeneity and stability of this material
were sufficient for its use as a reference material. Values for elemental mass fractions in the material were statistically
determined based on the analytical results of the participating laboratories. Eighteen certified values and 14 reference values
were obtained. The diameters, obtained from a micrographic image using image analysis software, of 99% of the particles were
less than 10 μm, demonstrating that almost all the particles in the material could be classified as particles of 10 μm or
less in aerodynamic diameter. The chemical composition and particle size distribution of this material were close to those
of an authentic aerosol collected in Beijing. NIES CRM 28 is appropriate for use in analytical quality control and in the
evaluation of methods used in the analysis of aerosols, particularly those collected in urban environments in northeast Asia
Figure New NIES CRM 28 Urban Aerosols and photo micrograph of the material 相似文献
14.
Eranda Wanigasekara Sirantha Perera Jeffrey A. Crank Leonard Sidisky Robert Shirey Alain Berthod Daniel W. Armstrong 《Analytical and bioanalytical chemistry》2010,396(1):511-524
Four new ionic liquids (IL) were prepared and bonded onto 5-μm silica particles for use as adsorbent in solid-phase microextraction
(SPME). Two ILs contained styrene units that allowed for polymerization and higher carbon content of the bonded silica particles.
Two polymeric ILs differing by their anion were used to prepare two SPME fibers that were used in both headspace and immersion
extractions and compared to commercial fibers. In both sets of experiments, ethyl acetate was used as an internal standard
to take into account adsorbent volume differences between the fibers. The polymeric IL fibers are very efficient in headspace
SPME for short-chain alcohols. Immersion SPME also can be used with the IL fibers for short-chain alcohols as well as for
polar and basic amines that can be extracted at pH 11 without damage to the IL-bonded silica particles. The sensitivities
of the two IL fibers differing by the anion were similar. Their efficacy compares favorably to that of commercial fibers for
polar analytes. The mechanical strength and durability of the polymeric IL fibers were excellent.
相似文献
15.
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
16.
André M. Striegel Samantha L. Isenberg Gregory L. Côté 《Analytical and bioanalytical chemistry》2009,394(7):1887-1893
Ultrahigh-molar-mass (M) polymers such as DNA, cellulose, and polyolefins are routinely analyzed using size-exclusion chromatography (SEC) to obtain
molar mass averages, distributions, and architectural information. It has long been contended that high-M polymers can degrade during SEC analysis; if true, the inaccurate molar mass information obtained can adversely affect decisions
regarding processing and end-use properties of the macromolecules. However, most evidence to the effect of degradation has
been circumstantial and open to alternative interpretation. For example, the shift in SEC elution volume as a function of
increased chromatographic flow rate, observed using only a concentration-sensitive detector, may be the result of degradation
or of elution via a nondegradatory slalom chromatography mechanism. Here, using both concentration-sensitive and multiangle
static light-scattering detection, we provide unambiguous evidence that the polysaccharide alternan actually degrades during
SEC analysis. The decrease in molar mass and size of alternan with increasing flow rate, measured using light scattering,
allows ruling out an SC mode of elution and can only be interpreted as due to degradation. These findings demonstrate the
extreme fragility of ultrahigh-M polymers and the care that must be taken for accurate characterization.
Figure Scission of alternan chains in liquid chromatography. 相似文献
17.
Application of surface chemical analysis tools for characterization of nanoparticles 总被引:1,自引:1,他引:0
D. R. Baer D. J. Gaspar P. Nachimuthu S. D. Techane D. G. Castner 《Analytical and bioanalytical chemistry》2010,396(3):983-1002
The important role that surface chemical analysis methods can and should play in the characterization of nanoparticles is
described. The types of information that can be obtained from analysis of nanoparticles using Auger electron spectroscopy
(AES), X-ray photoelectron spectroscopy (XPS), time-of-flight secondary-ion mass spectrometry (TOF-SIMS), low-energy ion scattering
(LEIS), and scanning-probe microscopy (SPM), including scanning tunneling microscopy (STM) and atomic force microscopy (AFM),
are briefly summarized. Examples describing the characterization of engineered nanoparticles are provided. Specific analysis
considerations and issues associated with using surface-analysis methods for the characterization of nanoparticles are discussed
and summarized, with the impact that shape instability, environmentally induced changes, deliberate and accidental coating,
etc., have on nanoparticle properties.
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18.
Nora Graf Thomas Gross Thomas Wirth Wilfried Weigel Wolfgang E. S. Unger 《Analytical and bioanalytical chemistry》2009,393(8):1907-1912
The chemical composition of the functional surfaces of substrates used for microarrays is one of the important parameters
that determine the quality of a microarray experiment. In addition to the commonly used contact angle measurements to determine
the wettability of functionalized supports, X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry
(ToF-SIMS) are more specific methods to elucidate details about the chemical surface constitution. XPS yields information
about the atomic composition of the surface, whereas from ToF-SIMS, information on the molecular species on the surface can
be concluded. Applied on printed DNA microarrays, both techniques provide impressive chemical images down to the micrometer
scale and can be utilized for label-free spot detection and characterization. Detailed information about the chemical constitution
of single spots of microarrays can be obtained by high-resolution XPS imaging.
Figure Eye-catching image for the graphical online abstract 相似文献
19.
Yveline Henchoz Bruno Bard Davy Guillarme Pierre-Alain Carrupt Jean-Luc Veuthey Sophie Martel 《Analytical and bioanalytical chemistry》2009,394(3):707-729
The measurement of physicochemical properties at an early phase of drug discovery and development is crucial to reduce attrition
rates due to poor biopharmaceutical properties. Among these properties, ionization, lipophilicity, solubility and permeability
are mandatory to predict the pharmacokinetic behavior of NCEs (new chemical entities). Due to the high number of NCEs, the
analytical tools used to measure these properties are automated and progressively adapted to high-throughput technologies.
The present review is dedicated to experimental methods applied in the early drug discovery process for the determination
of solubility, ionization constants, lipophilicity and permeability of small molecules. The principles and experimental conditions
of the different methods are described, and important enhancements in terms of throughput are highlighted.
Figure Scheme of the Drug Research Process. 相似文献
20.
Particle size and shape and their distribution directly influence a variety of end-use material properties related to packing,
mixing, and transport of powders, solutions, and suspensions. Many of the techniques currently employed for particle size
characterization have found limited applicability for broadly polydisperse and/or nonspherical particles. Here, we introduce
a quadruple-detector hydrodynamic chromatography (HDC) method utilizing static multiangle light scattering (MALS), quasi-elastic
light scattering (QELS), differential viscometry (VISC), and differential refractometry (DRI), and apply the technique to
characterizing a series of solid and hollow polystyrene latexes with diameters in the approximate range of 40–400 nm. Using
HDC/MALS/QELS/VISC/DRI, we were able to determine a multiplicity of size parameters and their polydispersity and to monitor
the size of the particles across the elution profile of each sample. Using self-similarity scaling relationships between the
molar mass and the various particle radii, we were also able to ascertain the shape of the latexes and the shape constancy
as a function of particle size. The particle shape for each latex was confirmed by the dimensionless ratio ρ ≡ R
G,z
/R
H,z
which, in addition, provided information on the structure (compactness) of the latexes as a function of particle size. Solid
and hollow polystyrene latex samples were also differentiable using these methods. Extension of this method to nonspherical,
fractal objects should be possible.
相似文献