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1.
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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2.
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
3.
Electrokinetic sample extraction and enrichment is introduced as a newly developed concept for the analysis of substances
in sludge-type or paste-like matrices. It is based on electrokinetic transport phenomena as electromigration and electroosmosis
occurring when an electrical field is applied to the fresh, wet samples. Problems usually associated to sample drying can
be avoided, e.g., losses of volatile analytes or contamination. We have designed and built a suitable apparatus for electrokinetic
sample extraction and enrichment. Appropriate operating conditions (field strength, buffer composition, concentration, and
volume) were identified in experiments with an artificial sludge model and real-world lake sediments. A proof of principle
of the method was provided by the electromigrative extraction and online enrichment on a solid-phase sorbent disk of an azo
dye from a diatomaceous earth slurry. Electroosmotic extraction and enrichment of a cyanobacterial hepatotoxin at trace levels
was finally investigated as an application example using lake sediments. Rather clean extracts were obtained even with high
organic content sediment samples, as shown by high-performance liquid chromatography with diode array detection.
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4.
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
5.
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
6.
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
7.
S. Pous-Torres J. R. Torres-Lapasió J. J. Baeza-Baeza M. C. García-álvarez-Coque 《Analytical and bioanalytical chemistry》2009,394(2):625-636
An indirect method for dead time (t
0) estimation in reversed-phase liquid chromatography, based on a relationship between retention time and organic solvent content,
is proposed. The method processes the retention data obtained in experimental designs. In order to get more general validity
and enhance the accuracy, the information from several compounds is used altogether in an alternating regression fashion.
The method was applied to nitrosamines, alkylbenzenes, phenols, benzene derivatives, polycyclic aromatic hydrocarbons and
β-blockers, among other compounds, chromatographed in a cyano and several C18 columns. A comprehensive validation was carried
out by comparing the results with those provided by the injection of markers, the observation of the solvent front and the
homologous series method. It was also found that different groups of compounds yielded the same t
0 value with the same column, which was verified in different solvent composition windows. The method allows improved models
useful for optimisation or for other purposes, since t
0 can be estimated with the retention data of the target solutes.
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8.
Tuulia Hyötyläinen 《Analytical and bioanalytical chemistry》2009,394(3):743-758
Sample preparation before chromatographic separation is the most time-consuming and error-prone part of the analytical procedure.
Therefore, selecting and optimizing an appropriate sample preparation scheme is a key factor in the final success of the analysis,
and the judicious choice of an appropriate procedure greatly influences the reliability and accuracy of a given analysis.
The main objective of this review is to critically evaluate the applicability, disadvantages, and advantages of various sample
preparation techniques. Particular emphasis is placed on extraction techniques suitable for both liquid and solid samples.
Figure Miniaturised extraction techniques allow sensitive analysis of also small sample volumes. 相似文献
9.
Han X Wang C He L Beesley TE Armstrong DW 《Analytical and bioanalytical chemistry》2007,387(8):2681-2697
A new synthetic polymeric chiral stationary phase for liquid chromatography was prepared via free-radical-initiated polymerization
of trans-9,10-dihydro-9,10-ethanoanthracene-(11S,12S)-11,12-dicarboxylic acid bis-4-vinylphenylamide. The new polymeric chiral stationary phase (CSP) showed enantioselectivity
for many chiral compounds in multiple mobile phases. High stability and sample capacities were observed on this polymeric
chiral stationary phase. Mobile phase components and additives affected chiral separation greatly. This new synthetic chiral
stationary phase is complementary to two other related commercially available CSPs: the P-CAP and P-CAP-DP columns. Interactions
between the chiral stationary phase and analytes that lead to retention and chiral recognition include hydrogen bonding, dipolar,
and π–π interactions. Repulsive (steric) interactions also contribute to chiral recognition.
Figure LC chromatograms showing the analytical (blue) and preparative (red) separations of N-(3,5-dinitrobenzoylleucine) enantiomers on a new synthetic polymeric chiral stationary phase 相似文献
10.
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
11.
The derivatization of cysteine-containing peptides with benzoquinone compounds is rapid, quantitative and specific in acidic
media. The conversion of cysteines into hydrophobic benzoquinone-adducted residues in peptides is used here to alter the chromatographic
properties of cysteinyl peptides during liquid chromatography separation. The benzoquinone derivatization is shown to allow
the accurate selection of cysteine-containing peptides of bovine serum albumin tryptic digest by diagonal reversed-phase chromatography,
which consists of one primary and a series of secondary identical liquid chromatographic separations, before and after a cysteinyl-targeted
modification of the peptides by benzoquinone compounds.
Figure Diagonal chromatographic selection of cysteinyl peptides modified with benzoquinones
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
12.
Determination of antimicrobial residues and metabolites in the aquatic environment by liquid chromatography tandem mass spectrometry 总被引:2,自引:0,他引:2
Antimicrobials are used in large quantities in human and veterinary medicine. Their environmental occurrence is of particular
concern due to the potential spread and maintenance of bacterial resistance. After intake by the organisms, the unchanged
drug and its metabolized forms are excreted and enter wastewater treatment plants where they are mostly incompletely eliminated,
and are therefore eventually released into the aquatic environment. The reliable detection of several antimicrobials in different
environmental aqueous compartments is the result of great improvements achieved in analytical chemistry. This article provides
an overview of the more outstanding analytical methods based on liquid chromatography tandem mass spectrometry, developed
and applied to determine antimicrobial residues and metabolites present in surface, waste, and ground waters.
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13.
A miniaturized fluorescence detector utilizing a three-dimensional windowless flow cell has been constructed and evaluated. The inlet and outlet liquid channels are collinear and are located in the same plane as the excitation paths, while the optical fiber used to collect the emission light is perpendicular to this plane. The straightforward arrangement of the flow path minimizes band dispersion and eliminates bubble formation or accumulation inside the cell. The use of high-brightness light-emitting diodes (LEDs) as the excitation source and a miniaturized metal package photomultiplier tube (PMT) results in a compact and sensitive fluorescence detector. The detection limit obtained from the system for fluorescein isothiocyanate (FITC) in flow injection mode is 2.6 nmol/L. The analysis of riboflavin and FITC by packed capillary liquid chromatography is demonstrated.
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14.
In proteomics, nanoflow multidimensional chromatography is now the gold standard for the separation of complex mixtures of
peptides as generated by in-solution digestion of whole-cell lysates. Ideally, the different stationary phases used in multidimensional
chromatography should provide orthogonal separation characteristics. For this reason, the combination of strong cation exchange
chromatography (SCX) and reversed-phase (RP) chromatography is the most widely used combination for the separation of peptides.
Here, we review the potential of hydrophilic interaction liquid chromatography (HILIC) as a separation tool in the multidimensional
separation of peptides in proteomics applications. Recent work has revealed that HILIC may provide an excellent alternative
to SCX, possessing several advantages in the area of separation power and targeted analysis of protein post-translational
modifications.
Figure Artistic impression of the HILIC separation mechanism 相似文献
15.
Christine Mousty 《Analytical and bioanalytical chemistry》2010,396(1):315-325
Two-dimensional layered inorganic solids, such as cationic clays and layered double hydroxides (LDHs), also defined as anionic
clays, have open structures which are favourable for interactions with enzymes and which intercalate redox mediators. This
review aims to show the interest in clays and LDHs as suitable host matrices likely to immobilize enzymes onto electrode surfaces
for biosensing applications. It is meant to provide an overview of the various types of electrochemical biosensors that have
been developed with these 2D layered materials, along with significant advances over the last several years. The different
biosensor configurations and their specific transduction procedures are discussed.
相似文献
16.
Bo Xu Xiaojun Feng Youzhi Xu Wei Du Qingming Luo Bi-Feng Liu 《Analytical and bioanalytical chemistry》2009,394(7):1911-1917
Analysis of complex biological samples requires the use of high-throughput analytical tools. In this work, a microfluidic
two-dimensional electrophoresis system was developed with mercury-lamp-induced fluorescence detection. Mixtures of 20 standard
amino acids were used to evaluate the separation performance of the system. After fluorescent labeling with fluorescein isothiocyanate,
mixtures of amino acids were separated by micellar electrokinetic chromatography in the first dimension and by capillary zone
electrophoresis in the second. A double electrokinetic valve system was employed for the sample injection and the switching
between separation channels. Under the optimized conditions, 20 standard amino acids were effectively separated within 20 min
with high resolution and repeatability. Quantitative analysis revealed linear dynamic ranges of over three orders of magnitudes
with detection limits at micromolar range. To further evaluate the reliability of the system, quantitative analysis of a commercial
nutrition supplement liquid was successfully demonstrated.
Figure 相似文献
17.
Lee WC Cheng CH Pan HH Chung TH Hwang CC 《Analytical and bioanalytical chemistry》2008,390(4):1101-1109
Recent efforts in the investigation of chromatographic characterization of molecularly imprinted polymers (MIPs) have focused
mainly on the nature of heterogeneous binding sites. More data on the thermodynamics than on the kinetic features of MIP columns
have been published. The present article addresses the sources of peak broadening and tailing, which are the main drawbacks
often associated with imprinted polymers in chromatography for practical applications. With use of the theory of nonlinear
chromatography, the peak properties of a MIP column, including the retention and peak broadening and tailing, can be well
interpreted. Efforts to improve chromatographic efficiency using MIPs prepared by approaches different from the conventional
method, including covalent imprinting and the format of uniformly sized spherical microbeads, are reviewed and discussed.
This review leads to the conclusion that nonlinear chromatography theory is useful for characterizing chromatographic features
of MIP columns, since a MIP is essentially an affinity-based chromatographic stationary phase. We expect more theoretical
and experimental studies on the kinetic aspects of MIP columns, especially the factors influencing the apparent rate constant,
as well as the analysis of the influences of mobile-phase composition on the chromatographic performance. In addition to revealing
the affinity interaction by molecular recognition, slow nonspecific interactions which may be inherited from the imperfect
imprinting and may be involved in the rebinding of the template to MIPs also need to be characterized.
Figure The peak broadening and tailing associated often with molecularly imprinted polymers (MIPs) in column chromatography for practical
applications can be well characterized by the theory of nonlinear chromatography. 相似文献
18.
A novel microextraction method is introduced based on dispersive liquid–liquid microextraction (DLLME) in which an in situ
metathesis reaction forms a water-immiscible ionic liquid (IL) that preconcentrates aromatic compounds from water followed
by separation using high-performance liquid chromatography. The simultaneous extraction and metathesis reaction forming the
IL-based extraction phase greatly decreases the extraction time as well as provides higher enrichment factors compared to
traditional IL DLLME and direct immersion single-drop microextraction methods. The effects of various experimental parameters
including type of extraction solvent, extraction and centrifugation times, volume of the sample solution, extraction IL and
exchanging reagent, and addition of organic solvent and salt were investigated and optimized for the extraction of 13 aromatic
compounds. The limits of detection for seven polycyclic aromatic hydrocarbons varied from 0.02 to 0.3 μg L−1. The method reproducibility produced relative standard deviation values ranging from 3.7% to 6.9%. Four real water samples
including tap water, well water, creek water, and river water were analyzed and yielded recoveries ranging from 84% to 115%.
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19.
Fourier transform infrared (FTIR) spectroscopic imaging is a relatively new method that has received great attention as a
new field of analytical chemistry. The greatest benefit of this technique lies in the high molecular sensitivity combined
with a spatial resolution down to a few micrometers. Another advantage is the ability to probe samples under native conditions,
which allows new insights into samples without the need for fixation, stains, or an additional marker. Advances in instrumentation
have made FTIR spectroscopic imaging the tool of choice for an increasing number of applications. The main applications are
in the bioanalytical chemistry of cells and tissue, polymers, and recently as well as in homeland security. This report gives
a short overview of current developments and recent applications.
Figure FTIR image of a polymer blend reveals the chemical composition. Online Abstract Figure (365 KB). 相似文献
20.
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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