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Tuesday 25 September 2012
Just Published: Analytica Chimica Acta
A new issue of this journal has just
been published. To see abstracts of the papers it contains (with links through
to the full papers) click here:
Publication year:
2012 Source:Analytica Chimica Acta, Volume 747 Shizuka Nakayama,
Herman O. Sintim Cations affect the topology and enzymatic proficiency of
most macromolecular catalysts but the role of cations in DNAzyme peroxidation
reactions remains unresolved. Herein, we use statistical methods (ANOVA, t-test
and Wilcoxon Mann–Whitney non-parametric test) to demonstrate that there are
strong associations between cations, DNAzyme topology, peroxidation substrate
and peroxidation rates of G-quadruplex peroxidises. Ammonium cation was found to
be superior to all tested cations, including potassium. A t-test indicated that
NH4 + was better than K+ with a p-value=0.05.
Interestingly, the nature of the peroxidation substrate employed affected the
dependence of peroxidation rate on the cation present and of the three
substrates tested, 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid
(ABTS), tyramine and 3,3′,5,5′-tetramethylbenzidine (TMB), ABTS was the most
sensitive to the nature of cation present.
Graphical abstract
Graphical abstract Highlights
►
G-quadruplex peroxidation rate depends on the cation present. ► NH4 +
is best cation amongst Li+, Na+, K+,
Cs+, Rb+, Sr2+, Br2+,
Pb2+ and Tb3+. ► ANOVA reveals cation effect is dependent
on DNAzyme topology and peroxidation substrate.
Publication year:
2012 Source:Analytica Chimica Acta, Volume 747 Muhammad
Najam-ul-Haq, Fahmida Jabeen, Dilshad Hussain, Adeela Saeed, Syed Ghulam
Musharraf, Christian W. Huck, Günther K. Bonn Protein phosphorylation is one
of the most important post-translational modifications. Phosphorylated peptides
are present in low abundance in blood serum but play a vital role in regulatory
mechanisms and may serve as casual factors in diseases. The enrichment and
analysis of phosphorylated peptides directly from human serum and mapping the
phosphorylation sites is a challenging task. Versatile nanocomposites of
different materials have been synthesized using simple but efficient
methodologies for their enrichment. The nanocomposites include magnetic, coated,
embedded as well as chemically derivatized materials. Different base materials
such as polymers, carbon based and metal oxides are used. The comparison of
nanocomposites with respective nanoparticles provides sufficient facts about
their efficiency in terms of loading capacity and capture efficiency. The cost
for preparing them is low and they hold great promise to be used as
chromatographic materials for phosphopeptide enrichment. This review gives an
overview of different nanocomposites in phosphoproteomics, discussing the
improved efficiency than the individual counterparts and highlighting their
significance in phosphopeptide enrichment.
Graphical abstract
Graphical abstract Highlights
►
Protein phosphorylation, the most important post-translational modification. ►
Enrichment of phosphopeptides for mapping protein phosphorylation sites. ►
Versatile nanocomposites of different materials. ► The nanocomposites include
magnetic, coated, embedded as well as chemically derivatized materials. ►
Different base materials such as polymers, carbon based and metal
oxides.
Publication year:
2012 Source:Analytica Chimica Acta, Volume 747 Jean Chrysostome
Ndamanisha, Li-ping Guo With its well-ordered pore structure, high specific
surface area and tunable pore diameters in the mesopore range, ordered
mesoporous carbon (OMC) is suitable for applications in catalysis and sensing.
We report recent applications of OMC in electrochemical sensors and biosensors.
After a brief description of the electrochemical properties, the
functionalization of the OMC for improvement of the electrocatalytic properties
is then presented. We show how the ordered mesostructure of OMC is very
important in those applications. The high density of edge plane-like defective
sites (EDSs), oxygen-containing groups and a large surface area on OMC may
provide many favorable sites for electron transfer to compounds, which makes OMC
a potential novel material for an investigation of the electrochemical behavior
of substances. Moreover, the structural capabilities of OMC at the scale of a
few nanometers agree with immobilization of other electrocataytic substances.
Interesting properties of this material may open up a new approach to study the
electrochemical determination of other biomolecules.
Graphical abstract
Graphical abstract Highlights
►
The preparation and functionalization of ordered mesoporous carbon. ► Their
applications as electrochemical sensors with high electrocatalytic activity. ► A
promising electrode material based on its interesting
properties.
Publication year:
2012 Source:Analytica Chimica Acta, Volume 747 Zeying He, Donghui
Liu, Ranhong Li, Zhiqiang Zhou, Peng Wang A magnetic solid phase extraction
(MSPE) method coupled with high-performance liquid chromatography (HPLC) was
proposed for the determination of five sulfonylurea herbicides
(bensulfuron-methyl, prosulfuron, pyrazosulfuron-ethyl, chlorimuron-ethyl and
triflusulfuron-methyl) in environmental water samples. The magnetic adsorbent
was prepared by incorporating Fe3O4 nanoparticles and surfactant into a silica
matrix according to a sol–gel procedure, which can provide surfactant free
extracts during the eluting step to avoid chromatographic interference. The
prepared adsorbent was used to extract the sulfonylurea herbicides in several
kinds of water samples. The main factors affecting the extraction efficiency,
including desorption conditions, extraction time, sample volume, and sample
solution pH were optimized. Under the optimum conditions, good linearity was
obtained within the range of 0.2–50.0μgL−1 for all analytes, with
correlation coefficients ranging from 0.9993 to 0.9999. The enrichment factors
were between 1200 and 1410, and the limits of detection were between 0.078 and
0.10μgL−1. The proposed method was successfully applied in the
analysis of sulfonylurea herbicides in environmental samples (tap, reservoir,
river, and rice field). The recoveries of the method ranged between 80.4% and
107.1%. This study reported for the first time the use of MSPE procedure in the
preconcentration of sulfonylurea herbicides in environmental samples. The
procedure proved to be efficient, environmentally friendly, and fast.
Graphical abstract
Graphical abstract Highlights
► A
novel adsorbent was prepared for magnetic solid phase extraction. ► Varieties of
experiment factors were optimized and selected. ► Good enrichment factors
(1200–1410) were obtained. ► This method has been successfully applied in the
analysis of real water samples.
Publication year:
2012 Source:Analytica Chimica Acta, Volume 747 You-Ya Zhou,
Chao-Yan Zhang, Zeng-Guang Yan, Ke-Ji Li, Lin Wang, Ya-Bo Xie, Fa-Sheng Li, Zhou
Liu, Jin Yang A micro-solid-phase extraction (μ-SPE) device was developed by
filling copper(II) isonicotinate coordination polymer (Cu(4-C5H4N-COO)2(H2O)4)
into a porous polypropylene envelope, and the μ-SPE, coupling with gas
chromatography (GC) with a micro-cell electron capture detector (μ-ECD), was
used for extraction and determination of PBDEs in soils. Variables affecting
extraction procedures, including temperature, water volume, extraction time, and
desorption time, were investigated in a spiked soil, and the parameters were
optimized. Under the optimal experimental conditions, the method detection
limits for seven PBDEs (BDE-28, 47, 99, 100, 153, 154, and 183) were in the
range of 0.026–0.066ngg−1, and the reproducibility was satisfactory
with the relative standard deviation in range of 1.3–10.1%. Good linear
relationship between PBDEs concentrations and GC signals (defined as peak area)
was obtained in the range between 0.1 and 200ngg−1. The recovery of
the seven PBDEs by μ-SPE varied from 70 to 90%, which was comparable to that
determined by accelerated solvent extraction method. Finally, the proposed
method was used to determine PBDEs in several field-contaminated soils, and it
was suggested that the μ-SPE is a promising alternative microextraction
technique for the detection of PBDEs in soils.
Graphical abstract
Graphical abstract Highlights
► A
Cu(4-C5H4N-COO)2(H2O)4-based μ-SPE device was developed for determining PBDEs. ►
Extraction parameters for determination of PBDEs using μ-SPE in soils were
optimized. ► The μ-SPE showed a high selectivity to PBDEs, especially lower
brominated PBDEs. ► The μ-SPE is a promising microextraction technique for
monitoring PBDEs in soils.
Publication year:
2012 Source:Analytica Chimica Acta, Volume 747 Iuliana Oita,
Hadewych Halewyck, Bert Thys, Bart Rombaut, Yvan Vander Heyden The
development of capillary electrophoretic applications aiming to provide reliable
stability assessment of viral suspensions, to detect subviral particles from
cell extracts or to study the interactions between virus particles and various
biomolecules, cannot be done without a thorough understanding of the sample
matrix contribution to the observed electrophoretic behaviour. The present study
thoroughly investigates the effect of the sample matrix on the electrophoretic
behaviour of poliovirus injected as sample plugs of 1%, 5% and 12% effective
capillary length. The effect of the sample matrix for three different poliovirus
batches was evaluated. Additionally, simulated samples, obtained from
concentrated poliovirus suspensions of high purity and diluted with commonly
used lab buffers in order to obtain samples with either high or low
conductivities, were also investigated. The goal of the study was to obtain a
better understanding of the effect of the sample matrix on the signal
enhancement, in order to define a general approach allowing a repeatable
capillary electrophoretic (CE) separation of poliovirus from complex samples.
This study clearly demonstrates that the sample matrix has an important
influence on the sensitivity of the CE poliovirus separations. Translation of
these observations into routine practice involves several compromises and a set
of rules in order to reduce day-to-day variation and to maximize sensitivity.
Graphical abstract
Graphical abstract Highlights
The effect of the small increase
in sample matrix conductivity on the electrophoretic profile of the poliovirus
suspensions. Separation conditions: uncoated fused silica capillary 40cm
effective length; 100mM borate buffer pH 8.3 with 25mM SDS; detection wavelength
205nm. Sample: highly purified poliovirus suspension after matrix removal and
concentration by ultrafiltration, diluted using the borate buffer pH 8.3 of
specified concentration, injected as 12% plug. ►
First study of the sample matrix impact on the CE signal enhancement of viruses.
► The effect of sample matrix variations from growth and purification is
discussed. ► Sample matrix importance for the CE sensitivity of poliovirus
separations is shown. ► Influence of the sample matrix on the preconcentration
mechanism is examined. ► Approaches for repeatable and reliable CE separations
of poliovirus are indicated.
Publication year:
2012 Source:Analytica Chimica Acta, Volume 747 Alexander W. Chassy,
Douglas O. Adams, V. Felipe Laurie, Andrew L. Waterhouse Phenolic compounds
in Vitis vinifera contribute important flavor, functionality, and health
qualities to both table and wine grapes. The plant phenolic metabolic pathway
has been well characterized, however many important questions remain regarding
the influence of environmental conditions on pathway regulation. As a diagnostic
for this pathway's regulation, we present a technique to incorporate a
stable-isotopic tracer, l-phenyl-13C6-alanine (Phe13),
into grape berries in situ and the accompanying high throughput analytical
method based on LC–DAD–MS/MS to quantify and track the label into phenylalanine
metabolites. Clusters of V. vinifera cv. Cabernet Sauvignon, either near the
onset of ripening or 4weeks later, were exposed to Phe13 in the
vineyard. Phe13 was present in berries 9days afterwards as well as
labeled flavonols and anthocyanins, all of which possessed a molecular ion shift
of 6amu. However, nearly all the label was found in anthocyanins, indicating
tight regulation of phenolic biosynthesis at this stage of maturity. This method
provides a framework for examining the regulation of phenolic metabolism at
different stages of maturity or under different environmental conditions.
Additionally, this technique could serve as a tool to further probe the
metabolism/catabolism of grape phenolics.
Graphical abstract
Graphical abstract Highlights
►
l-Phenyl-13C6-alanine was incorporated into grape berries, intact on
the vine, at two stages of maturity. ► Labeled anthocyanins were synthesized by
the berry and quantified by LC–UV/Vis–MS/MS. ► Extremely tight regulation of
phenylpropanoid pathways was observed.
Publication year:
2012 Source:Analytica Chimica Acta, Volume 747 Emanuela Gionfriddo,
Attilio Naccarato, Giovanni Sindona, Antonio Tagarelli A new analytical
approach is exploited in the assay of selenium speciation in selenized and not
selenium enriched potatoes based on the widely available solid-phase
microextraction (SPME) coupled to-GC–triple quadrupole mass spectrometry
(SPME-GC–QqQ MS) method. The assay of selenomethionine (SeMet) and
selenomethylselenocysteine (SeMeSeCys) in potatoes here reported provides clues
to the effectiveness of SPME technique combined with gas chromatography–tandem
mass spectrometry, which could be of general use. For the exploitation of the GC
method, the selected analytes were converted into their N(O,S)-alkoxycarbonyl
alkyl esters derivatives by direct treatment with alkyl chloroformate in aqueous
extracts. The performance of five SPME fibers and three chloroformates were
tested in univariate mode and the best results were obtained using the
divinylbenzene/carboxen/polydimethylsiloxane fiber and propylchloroformate. The
variables affecting the efficiency of SPME analysis were optimized by the
multivariate approach of design of experiment (DoE) and, in particular, a
central composite design (CCD) was applied. Tandem mass spectrometry in selected
reaction monitoring (SRM) has allowed the elimination of matrix interferences,
providing reconstructed chromatograms with well-resolved peaks and the
achievement of very satisfactory detection and quantification limits. Both
precision and recovery of the proposed protocol tested at concentration of 8 and
40μgkg−1 (dry matter), offered values ranging from 82.3 to 116.3% and
from 8.5 to 13.1% for recovery and precision, respectively. The application of
the method to commercial samples of selenized and not selenium enriched potatoes
proved that the Se fertilization increases significantly the concentration of
these bioavailable selenoamino acids.
Graphical abstract
Graphical abstract Highlights
► A
SPME-GC–QqQ MS approach was developed for free SeAA quantification in aqueous
extracts. ► Possibility to use an available commercial instrument as GC–QqQ MS
for analyzing SeAA. ► Application to commercial samples of selenized and not
selenium enriched potatoes. ► The Se fertilization increases the concentration
of studied SeAA in selenized potatoes.
Publication year:
2012 Source:Analytica Chimica Acta, Volume 747 Susan A. Mackintosh,
Alicia Pérez-Fuentetaja, Lisa R. Zimmerman, Grazina Pacepavicius, Mark Clapsadl,
Mehran Alaee, Diana S. Aga Polybrominated diphenyl ethers (PBDEs) are a class
of flame retardants used globally in many consumer products and industrial
applications. Traditionally, gas chromatography–high resolution mass
spectrometry (GC–HR-MS) is the method of choice for analysis of PBDEs in
environmental samples because it offers high sensitivity and selectivity,
resulting in less interferences. However, the specificity offered by gas
chromatography-triple quadrupole tandem mass spectrometry (GC–QQQ-MS/MS),
operated in selected reaction monitoring mode, provides a more affordable
alternative to GC–HR-MS for the analysis of PBDEs in complex environmental
samples. In this study, an analytical method was developed for the analysis of
41 PBDE congeners in fish using GC–QQQ-MS/MS. Results from the analysis of three
fish species [lake trout (Salvelinus namaycush), yellow perch (Perca
flavescens), and round goby (Neogobius melanostomus)] using GC–QQQ-MS/MS were
compared with those obtained by GC–HR-MS. These species were selected because
they represent varying levels of lipid-rich matrix and contaminant loads.
Instrumental limits of detection for the GC–QQQ-MS/MS ranged from 0.04pg to
41pg, whereas those for the GC–HR-MS ranged from 5pg to 85pg. The PBDE values
obtained from these two methods were highly correlated, R 2 values
>0.7, for all three fish species, supporting the suitability of GC–QQQ-MS/MS
for analysis of PBDEs in fish with varying fat content.
Graphical abstract
Graphical abstract Highlights
► A
GC–QQQ-MS/MS method was developed for the analysis of PBDE congeners in fish. ►
This method was directly compared with a GC–HR-MS analysis of the same samples.
► Limits of detection were found to be comparable between the two instruments. ►
GC–QQQ-MS/MS results were not statistically different from the GC–HR-MS results.
► Findings support the suitability of GC–QQQ-MS/MS for analysis of PBDEs in
fish.
Publication year:
2012 Source:Analytica Chimica Acta, Volume 747 Gang Fan, Meng Ying
Zhang, Xiang Dong Zhou, Xian Rong Lai, Qing Hong Yue, Ce Tang, Wei Zao Luo, Yi
Zhang Rhizoma coptidis, a broadly used traditional Chinese medicine, derives
from the dried rhizomes of Coptis chinensis Franch, Coptis deltoidea C.Y. Cheng
et Hsiao and Coptis teeta Wall. Quantitative determination of protoberberine
alkaloids in R. coptidis is critical for controlling its quality. In this study,
a rapid, simple and accurate quantitative 1H NMR (qNMR) method was
developed for simultaneous determination of berberine, jatrorrhizine,
epiberberine, coptisine, palmatine and columbamine in R. coptidis from the three
species. Method validation was performed in terms of selectivity, precision,
repeatability, stability, accuracy, robustness and linearity. The average
recoveries obtained were in the range of 96.9–102.4% for all the six alkaloids.
In addition, the qNMR data were analyzed with analysis of variance (ANOVA),
hierarchical clustering analysis (HCA) and principal component analysis (PCA),
and the results showed that the contents of the active alkaloids have
significant difference among the three species. Compared with the conventional
HPLC approach, the proposed qNMR method was demonstrated to be a powerful tool
for quantifying the six alkaloids due to its unique advantages of high
robustness, rapid analysis time and no need of standard compounds for
calibration curves preparation. These findings indicate that this method has
potential as a reliable method for quality evaluation of herb medicines,
especially for protoberberine alkaloid-containing ones.
Graphical abstract
Graphical abstract Highlights
► We
report a qNMR method for the determination of six alkaloids in Rhizoma coptidis.
► The results of the qNMR method are reliable by comparison with a HPLC method.
► The proposed method has good selectivity, precision, repeatability and
accuracy. ► This method coupled with chemometrics can distinguish three Rhizoma
coptidis species.
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