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1.
Two-dimensional liquid chromatography of synthetic polymers 总被引:2,自引:0,他引:2
Dušan Berek 《Analytical and bioanalytical chemistry》2010,396(1):421-441
Two-dimensional liquid chromatography, 2D-LC of synthetic polymers is critically assessed. Similarities and differences of
2D-LC of low-molecular-mass and polymeric substances are reviewed. The rationale of application of 2D-LC to macromolecular
substances is discussed. Basic information on retention mechanisms in liquid chromatography of synthetic polymers is furnished.
The principles, reasons, and significance of coupling of retention mechanisms are explained. The resulting separation processes
are elucidated, and the technical concepts of the corresponding experimental arrangements are described. The benefits of 2D-LC
are demonstrated together with numerous problems and shortcomings of the method.
相似文献
2.
Harir M Frommberger M Gaspar A Martens D Kettrup A El Azzouzi M Schmitt-Kopplin P 《Analytical and bioanalytical chemistry》2007,389(5):1459-1467
The photodecomposition of imazamox, a herbicide of the imidazolinone family, was investigated in pure water. The main photoproducts
from the photolysis were followed over time by liquid chromatography mass spectrometry and structures were proposed from exact
mass determinations obtained by electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry. The method
comprised exact mass determination with better than 0.2 ppm mass accuracy and a corresponding structural visualization taking
care of respective isotopes with an adapted van Krevelen diagram that enabled a systematic approach to the characterisation
of the elementary composition of each photoproduct. By taking advantage of the high resolving power of FT-ICR MS to make precise
formula assignments, the derived 2D van Krevelen diagram (O/C; H/C; m/z) enabled one to structurally differentiate the formed photoproducts and to propose a degradation pathway for imazamox.
Figure Overview of applied method to analyse the photolysis process of imazamox herbicide 相似文献
3.
Beatriz Fernández Jose Manuel Costa Rosario Pereiro Alfredo Sanz-Medel 《Analytical and bioanalytical chemistry》2010,396(1):15-29
Inorganic mass spectrometry techniques may offer great potential for the characterisation at the nanoscale, because they provide
unique elemental information of great value for a better understanding of processes occurring at nanometre-length dimensions.
Two main groups of techniques are reviewed: those allowing direct solid analysis with spatial resolution capabilities, i.e.
lateral (imaging) and/or in-depth profile, and those for the analysis of liquids containing colloids. In this context, the
present capabilities of widespread elemental mass spectrometry techniques such as laser ablation coupled with inductively
coupled plasma mass spectrometry (ICP-MS), glow discharge mass spectrometry and secondary ion/neutral mass spectrometry are
described and compared through selected examples from various scientific fields. On the other hand, approaches for the characterisation
(i.e. size, composition, presence of impurities, etc.) of colloidal solutions containing nanoparticles by the well-established
ICP-MS technique are described. In this latter case, the capabilities derived from the on-line coupling of separation techniques
such as field-flow fractionation and liquid chromatography with ICP-MS are also assessed. Finally, appealing trends using
ICP-MS for bioassays with biomolecules labelled with nanoparticles are delineated.
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4.
The purpose of this study was to optimize chromatographic and detection conditions for the simultaneous determination of water-soluble
vitamins in multi-vitamin dietary supplements using a single chromatographic run. An approach using liquid chromatography
with diode array and/or mass spectrometry for quantitation of seven B-complex vitamins [thiamine (B1), riboflavin (B2), nicotinamide (B3), pyridoxine (B6) pyridoxine, biotin, pantothenic acid, and folic acid] in multi-vitamin/multi-mineral daily supplements is described. This
approach utilizes a reversed phase C18 column (4 μm; i.d.: 250×2.0 mm) with a gradient mobile elution profile, performed at
a flow rate of 0.25 ml/min. After a 5-min isocratic elution at 100% A (0.1% formic acid in water), a linear gradient to 50%
A and 50% B (0.1% formic acid in acetonitrile) at 15 min and then to 5% A and 95% B at 17 min was employed. Detection was
performed with a photodiode array detector (DAD) in sequence with a triple-quad mass spectrometer in the multiple reaction
mode (MS-MRM). Although good chromatographic separation of ascorbic acid was also obtained in extracts from multi-vitamin/multi-mineral
supplements, the ascorbic acid could not be quantified properly due to rapid oxidation catalyzed by the minerals. This method
was initially applied to determine water-soluble vitamins in representative multi-vitamin/multi-mineral tablets following
the extraction of ground samples with a phosphate buffer (10 mM, pH 2.5). For multi-vitamin supplement tablets, this approach does not require any sample clean-up/pre-concentration steps
except for centrifugation and filtration of the extract.
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5.
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
6.
Pérez Pavón JL García Pinto C Guerrero Peña A Moreno Cordero B 《Analytical and bioanalytical chemistry》2008,391(2):599-607
In the present work we report the results obtained with a methodology based on direct coupling of a headspace generator to
a mass spectrometer for the identification of different types of petroleum crudes in polluted soils. With no prior treatment,
the samples are subjected to the headspace generation process and the volatiles generated are introduced directly into the
mass spectrometer, thereby obtaining a fingerprint of volatiles in the sample analysed. The mass spectrum corresponding to
the mass/charge ratios (m/z) contains the information related to the composition of the headspace and is used as the analytical signal for the characterization
of the samples. The signals obtained for the different samples were treated by chemometric techniques to obtain the desired
information. The main advantage of the proposed methodology is that no prior chromatographic separation and no sample manipulation
are required. The method is rapid, simple and, in view of the results, highly promising for the implementation of a new approach
for oil spill identification in soils.
Figure PCA score plots illustrate clear discrimination of types of crude oil in polluted soil samples (e.g. results are shown for
vertisol) 相似文献
7.
Nirogi RV Kandikere VN Shukla M Mudigonda K Shrivasthava W Datla PV Yerramilli A 《Analytical and bioanalytical chemistry》2006,384(3):780-790
A simple, rapid, sensitive and selective liquid chromatography/electrospray tandem mass spectrometry method was developed
and validated for the simultaneous quantification of cilostazol and its primary metabolite 3,4-dehydrocilostazol in human
plasma using mosapride as an internal standard. The method involves a simple one-step liquid-liquid extraction with a diethyl
ether and dichloromethane mixture (7:3). The analytes were chromatographed using an isocratic mobile phase on a reversed-phase
C18 column and analyzed by mass spectrometry in the multiple reaction monitoring mode using the respective [M+H]+ ions, m/z 370/288 for cilostazol, m/z 368/286 for 3,4-dehydrocilostazol and m/z 422/198 for the internal standard. The assay exhibited a linear dynamic range of 5–2,000 ng/mL for cilostazol and 5–400 ng/mL
for 3,4-dehydrocilostazol in human plasma. The lower limit of quantitation was 5 ng/mL for both cilostazol and its metabolite.
Acceptable precision and accuracy were obtained for concentrations over the standard curve ranges. A run time of 2.5 min for
each sample made it possible to analyze more than 400 human plasma samples per day. The validated method has been successfully
used to analyze human plasma samples for application in pharmacokinetics, bioavailability or bioequivalence studies.
相似文献
8.
Separation and detection of seven V-type (venomous) and G-type (German) organophosphorus nerve agent degradation products
by gas chromatography with inductively coupled plasma mass spectrometry (GC–ICPMS) is described. The nonvolatile alkyl phosphonic
acid degradation products of interest included ethyl methylphosphonic acid (EMPA, VX acid), isopropyl methylphosphonic acid
(IMPA, GB acid), ethyl hydrogen dimethylamidophosphate sodium salt (EDPA, GA acid), isobutyl hydrogen methylphosphonate (IBMPA,
RVX acid), as well as pinacolyl methylphosphonic acid (PMPA), methylphosphonic acid (MPA), and cyclohexyl methylphosphonic
acid (CMPA, GF acid). N-(tert-Butyldimethylsilyl)-N-methyltrifluroacetamide with 1% TBDMSCl was utilized to form the volatile TBDMS derivatives of the nerve agent degradation
products for separation by GC. Exact mass confirmation of the formation of six of the TBDMS derivatives was obtained by GC–time
of flight mass spectrometry (TOF-MS). The method developed here allowed for the separation and detection of all seven TBDMS
derivatives as well as phosphate in less than ten minutes. Detection limits for the developed method were less than 5 pg with
retention times and peak area precisions of less than 0.01 and 6%, respectively. This method was successfully applied to river
water and soil matrices. To date this is the first work describing the analysis of chemical warfare agent (CWA) degradation
products by GC–ICPMS.
Figure Illustrated here are six parent organophosphorus nerve agents corresponding to the degradation products analyzed by gas chromatography
with ICPMS and ToF-MS detection. The authors would like to thank Daisy-Malloy Hamburg and Kevin M. Kubachka for creating this
figure 相似文献
9.
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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10.
11.
n-Butyl benzyl phthalate (BBP) is an endocrine-disrupting chemical. A bacterium species capable of using BBP as the sole source
of carbon and energy was isolated from mangrove sediment. Effects of BBP concentration, pH, temperature, and salinity on BBP
biodegradation were studied. The optimum pH, temperature, and salinity for the BBP biodegradation were 7.0, 37°C, and 15 g L−1, respectively. BBP was completely degraded within 6 days under optimum conditions, and the biodegradation of BBP could be
fitted to a first-order kinetic model. The major metabolites of BBP biodegradation were identified as mono-butyl phthalate,
mono-benzyl phthalate, phthalic acid, and benzoic acid by using high-performance liquid chromatography and gas chromatography–mass
spectrometry. A preliminary metabolic pathway was proposed for the biodegradation of BBP.
相似文献
12.
Dmitrii A. Guschin Halyna Shkil Wolfgang Schuhmann 《Analytical and bioanalytical chemistry》2009,395(6):1693-1706
Electrodeposition polymers can be precipitated on electrode surfaces upon electrochemical-induced modulations of the pH value
in the diffusion zone in front of the electrode. The formed polymer films can be used as immobilization matrices in amperometric
biosensors. In order to rationally control the thus obtained biosensor properties, it is indispensable to develop strategies
for the reproducible synthesis of electrodeposition polymers as well as methods for the non-manual and reproducible sensor
fabrication. Based on instrumental developments such as a specifically designed parallel synthesizer with improved stirring
and temperature control, an automatic pipetting robot for the preparation of the monomer mixtures and controlled removal of
polymerization inhibitors, the reproducible synthesis of libraries of electrodeposition polymers was achieved. Moreover, the
polymerization process could be monitored using in-line thermocouples, and it could be shown that the chosen strategies led
to reproducible polymerization reactions. By adaptation of an electrochemical robotic system integrating a Au microtiter plate
and automatic electrode cleaning by means of a polishing wheel reproducible biosensor fabrication using glucose oxidase as
a model enzyme could be demonstrated. These results open the route for the rational development of biosensors and control
of the sensor properties by choosing specifically designed electrodeposition polymers.
相似文献
13.
Kahina Si-Ahmed Fairouz Tazerouti Ahmed Y. Badjah-Hadj-Ahmed 《Analytical and bioanalytical chemistry》2009,395(2):507-518
In order to study the effect of the nature and the length of the spacer, three mixed 10-undecenoate/phenylcarbamate derivatives
of β-cyclodextrin have been prepared and linked to allylsilica gel by means of a radical reaction. The chiral recognition
ability of the resulting materials, when used as liquid chromatography chiral stationary phases (CSPs), was evaluated using
heptane and either 2-propanol or chloroform as organic mobile-phase modifiers. A large variety of racemic compounds have been
separated successfully on these CSPs (mainly pharmaceuticals and herbicides). Optimization of these separations was discussed
in terms of mobile-phase composition and structural patterns of the injected analytes. The efficiencies of the three prepared
materials were compared to those of previously described perphenylated-β-cyclodextrin column and to analogous cellulose derivative-based
CSPs.
Schematic illustration of the b-cyclodextrin/mandelic acid inclusion complex 相似文献
14.
Ute Pyell Wendelin Bücking Carolin Huhn Barbara Herrmann Alexey Merkoulov Joachim Mannhardt Hartmut Jungclas Thomas Nann 《Analytical and bioanalytical chemistry》2009,395(6):1681-1691
Although colloidal nanoparticles show an electrophoretic heterogeneity under the conditions of capillary electrophoresis,
which can be either due to the particle-size distribution and/or the particle shape distribution and/or the zeta-potential
distribution, they can form correct isotachophoretic zones with sharp-moving boundaries. Therefore, the technique of isotachophoresis
permits to generate plugs in which the co-ions and counter ions of the original colloidal solution are removed and replaced
by the buffering counter ions of the leading electrolyte. It is shown that analytical isotachophoresis can be used to measure
directly, without calibration, the molar (particle) concentration of dispersed ionic colloids provided that the transference
number and the mean effective charge number of the particles (within the isotachophoretic zone) can be determined with adequate
accuracy. The method can also be used to measure directly the effective charge number of biomacromolecules or colloidal particles,
if solutions with known molar (particle) concentration can be prepared. The validity of the approach was confirmed for a model
solution containing a known molar concentration of bovine serum albumin.
相似文献
15.
Alain Walcarius 《Analytical and bioanalytical chemistry》2010,396(1):261-272
Nano- and/or macrostructuring of electrode surfaces has recently emerged as a powerful method of improving the performances
of electrochemical devices by enhancing both molecular accessibility and rapid mass transport via diffusion, by increasing
the electroactive surface area in comparison to the geometric one, and/or by providing confinement platforms for hosting suitable
reagents. This brief overview highlights how template technology offers advantages in terms of designing new types of porous
electrodes—mostly based on thin films, and functionalized or not—and discusses their use in analytical chemistry via some
recent examples from the literature on electrochemical sensors and biosensors.
相似文献
16.
Pyochelin is a siderophore and virulence factor common to Burkholderia cepacia and several Pseudomonas strains. It is isolated from bacterial media as a mixture of two epimers, which readily equilibrate in most solvents. Experiments based on high-performance liquid chromatography/electrospray ionization mass spectrometry are reported here, allowing the investigation of the different Fe(III)-chelating properties of pyochelin diastereomers in solution without the need for labourious isolation. It is demonstrated in this study that only one of the two pyochelin diastereomers is able to chelate Fe(III); no Fe(III) complexes of the other diastereomer could be detected. The Fe(III)–pyochelin complex exhibited a 1:1 metal-to-siderophore ratio and no evidence for other stoichiometries was found.
相似文献
17.
András Gergely Péter Horváth György Szász Gábor Veress 《Analytical and bioanalytical chemistry》2009,394(8):2105-2109
A three-step gradient reversed-phase high-performance liquid chromatography (RP-HPLC) method was developed for the separation
of dehydroepiandrosterone (DHEA), its sulfate ester (DHEA-S), its three C7-oxidized metabolites (7αOH-DHEA, 7βOH-DHEA, 7-keto-DHEA),
and its biosynthetic congeners (androstenedione, testosterone, estradiol, pregnenolone). This new method allows the quantitative
characterization of DHEA metabolism and biosynthetic transformation under given physiological, pathological, or therapeutically
influenced circumstances. Tetrahydrofuran probably acts as a proton acceptor coadsorbent, while isopropanol behaves as a proton
donor during the separation of testosterone, estradiol, and the stereoisomers of 7-OH-DHEA.
Figure Optimized gradient RP-HPLC results in full separation of DHEA from its biosynthetic congeners and metabolites 相似文献
18.
Patrícia da Fonseca Pierina Sueli Bonato 《Analytical and bioanalytical chemistry》2010,396(2):817-824
A three-phase LPME (liquid-phase microextraction) method for the enantioselective analysis of venlafaxine (VF) metabolites
(O-desmethylvenlafaxine (ODV) and N-desmethylvenlafaxine (NDV) in microsomal preparations is described for the first time. The assay involves the chiral HPLC
separation of drug and metabolites using a Chiralpak AD column under normal-phase mode of elution and detection at 230 nm.
The LPME procedure was optimized using multifactorial experiments and the following optimal condition was established: sample
agitation at 1,750 rpm, 20 min of extraction, acetic acid 0.1 mol/L as acceptor phase, 1-octanol as organic phase and donor
phase pH adjustment to 10.0. Under these conditions, the mean recoveries were 41% and 42% for (−)-(R)-ODV and (+)-(S)-ODV, respectively, and 47% and 48% for (−)-(R)-NDV and (+)-(S)-NDV, respectively. The method presented quantification limits of 200 ng/mL and it was linear over the concentration
range of 200–5,000 ng/mL for all analytes. The validated method was employed to study the in vitro biotransformation of VF
using rat liver microsomal fraction. The results demonstrated the enantioselective biotransformation of VF.
相似文献
19.
Rodríguez-Fariñas N Gomez-Gomez MM Camara-Rica C 《Analytical and bioanalytical chemistry》2008,390(1):29-35
Oral administration of sodium tungstate is an effective treatment for type 1 and 2 diabetes in animal models; it does not
incur significant side effects, and it may constitute an alternative to insulin. However, the mechanism by which tungstate
exerts its observed metabolic effects in vivo is still not completely understood. In this work, serum-containing proteins
which bind tungstate have been characterized. Size exclusion chromatography (SEC) coupled to inductively coupled plasma mass
spectrometry (ICP-MS) with a Phenomenex Bio-Sep-S 2000 column and 20 mM HEPES and 150 mM NaCl at pH 7.4 as the mobile phase
was chosen as the most appropriate methodology to screen for tungsten–protein complexes. When human serum was incubated with
tungstate, three analytical peaks were observed, one related to tungstate–albumin binding, one to free tungstate, and one
to an unknown protein binding (MW higher than 300 kDa). Matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF)
mass spectrometric analysis of the tungsten-containing fractions collected from SEC–ICP-MS chromatograms, after desalting
and preconcentration processes, confirmed the association of tungstate with albumin and the other unknown protein.
Figure SEC-ICP-MS // MALDI-TOF 相似文献
20.
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