This blog has been set up for editors, reviewers, authors and readers of Elsevier's Analytical Chemistry Journals - all of which can be seen below. It will be updated from Monday to Friday with general news and announcements concerning the titles listed on this page. It should be noted that the views or claims made in the news items and feeds are not necessarily those of the Publisher.
World Congress on Biosensors 2014
Biosensors 2014
Tuesday, 10 July 2012
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 738 R. Dario Arrua,
Mohammad Talebi, Tim J. Causon, Emily F. Hilder In recent years the use of
monolithic polymers in separation science has greatly increased due to the
advantages these materials present over particle-based stationary phases, such
as their relative ease of preparation and good permeability. For these reasons,
these materials present high potential as stationary phases for the separation
and purification of large molecules such as proteins, peptides, nucleic acids
and cells. An example of this is the wide range of commercial available
polymer-based monolithic columns now present in the market. This review
summarizes recent developments in the synthesis of monolithic polymers for
separation science, such as the incorporation of nanostructures in the polymeric
scaffold as well as the preparation of hybrid structures. The different methods
used in the surface functionalization of monolithic columns are also reviewed.
Finally, we critically discuss the recent applications of this column technology
in the separation of large molecules under different chromatographic mode.
Graphical abstract
Graphical abstract Highlights
►
This review summarizes recent developments in the synthesis of polymer
monoliths. ► Alternative preparation methods still remain an important area of
research. ► The application of monoliths in the separation of large molecules is
discussed. ► The use of polymer monoliths in the separation of real samples is
still needed.
Publication year:
2012 Source:Analytica Chimica Acta, Volume 738 Henryk H. Jeleń,
Małgorzata Majcher, Mariusz Dziadas Food flavor compounds due to the
complexity of food as a matrix, and usually their very low concentrations in a
product, as well as their low odor thresholds, create a challenge in their
extraction, separation and quantitation. Food flavor volatiles represent
compounds of different polarity, volatility and chemical character, which
determine method of extraction for their isolation from food. Microextraction
techniques, mainly SPME and SBSE have been used for food flavor compounds
analysis for two decades. Microextraction methods other than SPME and SBSE are
seldom used despite their analytical potential. The review discusses the nature
of food flavor compounds, and different approaches to food flavor analysis. It
summarizes the use of microextraction methods in food flavor compounds analysis
based on papers published in the last 5years, and discusses the potential of
microextraction methods in this field.
Graphical abstract
Graphical abstract Highlights
►
Microextraction methods in food flavors analysis based on 2006–2011 published
papers discussed. ► SPME, SBSE, LPME methods as dominating summarized in detail.
► Potential of other, less popular in this field microextraction methods
pronounced.
Publication year:
2012 Source:Analytica Chimica Acta, Volume 738 Mingzhi Dai,
Stephanie Maxwell, Bryan D. Vogt, Jeffrey T. La Belle Two ordered,
soft-templated mesoporous carbon powders with cubic and hexagonal framework
structure and four different commercial, low cost methacrylate-based polymer
binders with widely varying physical properties are investigated as screen
printed electrodes for glucose sensors using glucose oxidase and ferricyanide as
the mediator. Both the chemistry and concentration of the binder in the
electrode formulation can significantly impact the performance.
Poly(hydroxybutyl methacrylate) as the binder provides hydrophilicity to enable
transport of species in the aqueous phase to the carbon surface, but yet is
sufficiently hydrophobic to provide mechanical robustness to the sensor. The
current from the mesoporous carbon electrodes can be more than an order of
magnitude greater than for a commercial printed carbon electrode (Zensor) with
improved sensitivity for model glucose solutions. Even when applying these
sensors to rabbit whole blood, the performance of these glucose sensors compares
favorably to a standard commercial glucose meter with the lower detection limit
of the mesoporous electrode being approximately 20mgdL−1 despite the
lack of a separation membrane to prevent non-specific events; these results
suggest that the small pore sizes and high surface areas associated with ordered
mesoporous carbons may effectively decrease some non-specific inferences for
electrochemical sensing.
Graphical abstract
Graphical abstract Highlights
. ►
We prepared screen printed glucose sensor with two different mesoporous carbons.
► We investigated low cost, fluorine-free methacrylate-based as polymer binders.
► Cubic structure carbon provided higher signal than hexagonal structure carbon.
► Hydrophilicity of the binder greatly impacted the performance of the sensor. ►
The best sensor accurately measured glucose level in rabbit
blood.
Publication year:
2012 Source:Analytica Chimica Acta, Volume 738 Shuxian Mao, Weifeng
Li, Yumei Long, Yifeng Tu, Anping Deng We here reported a simple
electrochemical method for the detection of tryptophan (Trp) based on the Ag@C
modified glassy carbon (Ag@C/GC) electrode. The Ag@C core–shell structured
nanoparticles were synthesized using one-pot hydrothermal method and
characterized by scanning electron microscope (SEM), transmission electron
microscope (TEM), and Fourier transform-infrared spectroscopy (FTIR). The
electrochemical behaviors of Trp on Ag@C/GC electrode were investigated and
exhibited a direct electrochemical process. The favorable electrochemical
properties of Ag@C/GC electrode were attributed to the synergistic effect of the
Ag core and carbon shell. The carbon shell cannot only protect Ag core but also
contribute to the enhanced substrate accessibility and Trp-substrate
interactions, while nano-Ag core can display good electrocatalytic activity to
Trp at the same time. Under the optimum experimental conditions the oxidation
peak current was linearly dependent on the Trp concentration in the range of
1.0×10−7 to 1.0×10−4 M with a detection limit of
4.0×10−8 M (S/N=3). In addition, the proposed electrode was applied
for the determination of Trp concentration in real samples and satisfactory
results were obtained. The technique offers enhanced sensitivity and may trigger
the possibilities of the Ag@C nanocomposite towards diverse applications in
biosensor and electroanalysis.
Graphical abstract
Graphical abstract Highlights
Ag@C and Colloidal carbon sphere
modified glassy carbon electrodes were prepared. It was clear that the Ag@C/GCE
exhibited enhanced electrocatalytic activity towards Trp, which could result
from the synergistic effect between Ag core and carbon shell. The Ag@C/GCE
showed excellent analytical properties in the determination of Trp. ► The electrochemical behavior of Ag@C core–shell
nanocomposite was firstly proposed. ► Ag@C/GC electrode exhibited favorable
electrocatalytic properties towards Trp. ► The good electrocatalysis was due to
the synergistic effect of Ag-core and C-shell. ► The Ag@C/GC electrode displayed
excellent analytical properties in determining Trp.
Publication year:
2012 Source:Analytica Chimica Acta, Volume 738 Ye Tian, Lianzhe Hu,
Shuang Han, Yali Yuan, Jianguo Wang, Guobao Xu Hydrogen evolution bothers
stripping analysis significantly. Dioctyl phthalate-based carbon paste electrode
exhibits extremely wide cathodic potential window. It is explored as a powerful
substrate electrode to solve the problem of hydrogen evolution and further
improve reproducibility for stripping analysis using bismuth-coated electrodes
for the first time. It was successfully applied to the simultaneous
determination of Zn2+, Cd2+, and Pb2+. Linear
responses are obtained for Zn2+ in the range of
10–100μgL−1 and for Pb2+ and Cd2+ in the range
of 5–100μgL−1. The detection limits for Zn2+,
Cd2+, and Pb2+ are 0.1μgL−1,
0.22μgL−1 and 0.44μgL−1, respectively. The method has been
successfully applied to the determination of Zn2+, Cd2+,
and Pb2+ in waste water samples. The detection strategy based on the
combination of dioctyl phthalate-based carbon paste electrode and bismuth-coated
electrodes holds great promise for stripping analysis.
Graphical abstract
Graphical abstract Highlights
. ►
Dioctyl phthalate-based CPE has extremely wide cathodic potential range. ► It
has been used for bismuth-based stripping analysis for the first time. ► It can
effectively avoid hydrogen evolution and improve reproducibility. ► It is
suitable for detecting more active metals such as zinc. ► It is a powerful
platform for bismuth-based electrochemical stripping analysis.
Publication year:
2012 Source:Analytica Chimica Acta, Volume 738 Chaogui Chen, Yan
Du, Jing Li, Xiurong Yang, Erkang Wang In this work, we explored a novel
fabrication method to construct Au and Ag electrodes on chip, utilizing the
different solubility of gold and silver in different etching solutions. KI-I2
etching solution and 50% HNO3 were chosen to dissolve the metal layers
alternatively. Planar electrodes with gold and silver could be simultaneously
and accurately patterned on chip using photolithographic technique. The
as-prepared electrode could be directly served as integrated three-electrode
system for electrochemical measurement. Based on it, a sensing strategy has been
carried out using home-made electrochemical sensing (ECS) chip, which depended
on the competition of double strand DNA and Hg(II)-mediated T–T base pairs
(T-Hg(II)-T). Actually, a mercury specific oligonucleotide (MSO) was immobilized
onto the thus-fabricated gold working electrode and employed as the sensing
element. Chronocoulometry (CC) was chosen to monitor the differences of surface
charge volume and quantify the concentrations of Hg(II) ions with a low
detection limit down to 1nM. Therefore, a facile method to fabricate Au and Ag
electrodes has been demonstrated to simplify the production of ECS chip. The ECS
chip was finally used for constructing an effective sensing platform for
sensitive Hg(II) determination, which held promising potential for designing ECS
chip in lab-on-a-chip device or point-of-care diagnosis.
Graphical abstract
Graphical abstract Highlights
In this work, we explored a
novel method to fabricate multi-metallic planar electrodes and constructed
electrochemical sensing (ECS) chip for Hg(II) determination. Chronocoulometry
was carried out to measure the differences of surface charge volume owing to
specific activity of T-Hg(II)-T formation competed with double strand DNA. The
facile fabrication of multi-planar electrodes and sensing platform endowed the
ECS chip with great promise in environmental monitoring. ► A novel fabrication method was explored to prepare
multi-metallic planar electrodes. ► Electrochemical sensing (ECS) chip has been
constructed for Hg(II) analysis. ► Sensing strategy based on T-Hg(II)-T
formation competed with dsDNA has been built. ► Chronocoulometry (CC) was
carried out to measure the differences of surface charge. ► It resulted in a
high sensitive, high selective Hg(II) determination in practical
samples.
Publication year:
2012 Source:Analytica Chimica Acta, Volume 738 Sang-Hee Jo, Ki-Hyun
Kim, Zang-Ho Shon, David Parker Air samples containing sulfur compounds are
often collected and stored in sample bags prior to analysis. The storage
stability of six gaseous sulfur compounds (H2S, CH3SH, DMS, CS2, DMDS and SO2)
was compared between two different bag materials (polyvinyl fluoride (PVF) and
polyester aluminum (PEA)) at five initial concentrations (1, 10, 100, 1000, and
10,000ppb). The response factors (RF) of these samples were determined after
storage periods of 0, 1, and 3days by gas chromatography–pulsed flame
photometric detector (GC–PFPD) combined with an air server (AS)/thermal desorber
(TD) system. Although concentration reduction occurred more rapidly from samples
of the high concentration standards (1000 and 10,000ppb), such trends were not
evident in their low concentration counterparts (1, 10, and 100ppb). As such,
temporal changes in RF values and the associated loss rates of most sulfur gases
were greatly affected by their initial concentration levels. Moreover, the
storability of oxidized sulfur compound (SO2) was greatly distinguished from
that of reduced sulfur compounds (RSCs), as the former almost disappeared in the
PVF bag even after one day. The results of our study confirm that storability of
gaseous sulfur species is affected interactively by such variables as initial
gas concentration level, bag material type, and oxidation status with the
associated reactivity.
Graphical abstract
Graphical abstract Highlights
►
Many sampling methods have been developed and tested for various sulfur gas
species. ► The analysis of actual field samples is yet subject to large sources
in the sampling stage. ► The factors governing the sorptive loss of sulfur gases
on bag sampling materials is assessed.
Publication year:
2012 Source:Analytica Chimica Acta, Volume 738 Ke Yu, Bing Li, Tong
Zhang Ultrahigh performance liquid chromatography–tandem mass spectrometry
(UHPLC–MS/MS) was utilized to develop a rapid, sensitive and reliable method
without solid phase extraction (SPE) pre-concentration for trace analysis of 11
pharmaceuticals and personal care products (PPCPs) in influent and effluent from
municipal wastewater treatment plants (WWTPs). This method not only shortened
the analysis time but also reduced analysis cost significantly by omitting SPE
process and avoiding the consumption of SPE cartridge. Detection parameters for
UHPLC–MS/MS analysis were optimized, including sample pH, eluent, mobile phase
(solvent and additive), column temperature, and flow rate. Under the optimal
conditions, all analytes were well separated and detected within 8.0min by
UHPLC–MS/MS. The method quantification limits (MQLs) for the 11 PPCPs ranged
from 0.040 to 88ngL−1 and from 0.030 to 90ngL−1 for
influent and effluent, respectively. The matrix effect was systematically
investigated and quantified for different types of samples. The analysis of
influent and effluent samples of two WWTPs in Hong Kong revealed the presence of
11 PPCPs, including acyclovir, benzophenone-3, benzylparaben, carbamazepine,
ethylparaben, fluconazole, fluoxetine, methylparaben, metronidazole,
propylparaben, and ranitidine. Their concentrations ranged from 9.1 to
1810ngL−1 in influent and from 6.5 to 823ngL−1 in effluent
samples collected from Hong Kong WWTPs.
Graphical abstract
Graphical abstract Highlights
►
Signal enhancements of 11 PPCPs were observed for non-SPE pre-concentrated
samples. ► MTnon-SPE shortened analysis time, reduced analysis cost, and was
more accurate. ► Good chromatographic separation of 11 PPCPs was achieved within
8.0min. ► Method quantification limits of 11 PPCPs were as low as
0.030–90ngL−1. ► Concentrations of 11 PPCPs were
6.5–1810ngL−1 in Hong Kong municipal wastewater.
Publication year:
2012 Source:Analytica Chimica Acta, Volume 738 Marco Righettoni,
Antonio Tricoli, Samuel Gass, Alex Schmid, Anton Amann, Sotiris E.
Pratsinis Breath analysis has the potential for early stage detection and
monitoring of illnesses to drastically reduce the corresponding medical
diagnostic costs and improve the quality of life of patients suffering from
chronic illnesses. In particular, the detection of acetone in the human breath
is promising for non-invasive diagnosis and painless monitoring of diabetes (no
finger pricking). Here, a portable acetone sensor consisting of flame-deposited
and in situ annealed, Si-doped epsilon-WO3 nanostructured films was developed.
The chamber volume was miniaturized while reaction-limited and transport-limited
gas flow rates were identified and sensing temperatures were optimized resulting
in a low detection limit of acetone (∼20ppb) with short response (10–15s) and
recovery times (35–70s). Furthermore, the sensor signal (response) was robust
against variations of the exhaled breath flow rate facilitating application of
these sensors at realistic relative humidities (80–90%) as in the human breath.
The acetone content in the breath of test persons was monitored continuously and
compared to that of state-of-the-art proton transfer reaction mass spectrometry
(PTR-MS). Such portable devices can accurately track breath acetone
concentration to become an alternative to more elaborate breath analysis
techniques.
Graphical abstract
Graphical abstract Highlights
►
Portable sensors were developed and tested for monitoring acetone in the human
breath. ► Acetone concentrations down to 20ppb were measured with short response
times (<30s). ► The present sensors were highly selective to acetone over
ethanol and water. ► Sensors were applied to human breath: good agreement with
highly sensitive PTR-MS. ► Tests with people at rest and during physical
activity showed the sensor robustness.
Publication year:
2012 Source:Analytica Chimica Acta, Volume 738 Yuling Cui, Huafeng
Chen, Li Hou, Bing Zhang, Bingqian Liu, Guonan Chen, Dianping Tang Methods
based on nanomaterial labels have been developed for electrochemical
immunosensors and immunoassays, but most involved low sensitivity. Herein a
novel class of molecular tags, nanogold–polyaniline–nanogold microspheres
(GPGs), was first synthesized and functionalized with horseradish
peroxidase-conjugated thyroid-stimulating hormone antibody (HRP-Ab2) for
sensitive electrochemical immunoassay of thyroid-stimulating hormone (TSH).
X-ray diffraction, confocal Raman spectroscopy, scanning electron microscope and
transmission electron microscope were employed to characterize the prepared
GPGs. Based on a sandwich-type immunoassay format, the assay was performed in pH
5.0 acetate buffer containing 6.0mmolL−1 H2O2 by using GPG-labeled
HRP-Ab2 as molecular tags. Compared with pure polyaniline nanospheres and gold
nanoparticles alone, the GPG hybrid nanostructures increased the surface area of
the nanomaterials, and enhanced the immobilized amount of HRP-Ab2. Several
labeling protocols comprising HRP-Ab2, nanogold particle-labeled HRP-Ab2, and
polyaniline nanospheres-labeled HRP-Ab2, were also investigated for
determination of TSH and improved analytical features were obtained by using the
GPG-labeled HRP-Ab2. With the GPG labeling method, the effects of incubation
time and pH of acetate buffer on the current responses of the immunosensors were
also studied. The strong attachment of HRP-Ab2 to the GPGs resulted in a good
repeatability and intermediate precision down to 7%. The dynamic concentration
range spanned from 0.01 to 20μIUmL−1 with a detection limit (LOD) of
0.005μIUmL−1 TSH at the 3s B criterion. Significantly, no significant
differences at the 0.05 significance level were encountered in the analysis of
15 spiking serum samples between the developed electrochemical immunoassay and
the commercially available enzyme-linked immunosorbent assay (ELISA) method for
determination of TSH.
Graphical abstract
Graphical abstract Highlights
. ►
A novel immunosensing strategy was designed for detection of thyroid-stimulating
hormone. ► Using nanogold–polyaniline–nanogold microspheres as molecular tags. ►
Improvement of electrochemical activity of nanolabels. ► Combination enzyme
labels with nanolabels for signal amplification.
Publication year:
2012 Source:Analytica Chimica Acta, Volume 738 Kahina Si-Ahmed,
Zeineb Aturki, Bezhan Chankvetadze, Salvatore Fanali Three
polysaccharide-based chiral stationary phases, Sepapak® 1,
Sepapak® 2 and Sepapak® 3 have been evaluated in the
present work for the stereoisomer separation of a group of 12 flavonoids
including flavanones (flavanone, 4′-methoxyflavanone, 6-methoxyflavanone,
7-methoxyflavanone, 2′-hydroxyflavanone, 4′-hydroxyflavanone,
6-hydroxyflavanone, 7-hydroxyflavanone, hesperetin, naringenin) and flavanone
glycosides (hesperidin, naringin) by nano-liquid chromatography (nano-LC). The
behaviour of these chiral stationary phases (CSPs) towards the selected
compounds was studied in capillary columns (100μm internal diameter (i.d.))
packed with the above mentioned CSPs using polar organic, reversed and normal
elution modes. The influence of nature and composition of the mobile phase in
terms of concentration and type of organic modifier, buffer type and water
content (reversed phase elution mode) on the enantioresolution (R s ), retention
factor (k) and enantioselectivity (α) was evaluated. Sepapak® 3
showed the best chromatographic results in terms of enantioresolution,
enantioselectivity and short analysis time, employing a polar organic phase
mode. A mixture of methanol/isopropanol (20/80, v/v) as mobile phase enabled the
chiral separation of eight flavanones with enantioresolution factor (R s ) in
the range 1.15–4.18. The same analytes were also resolved employing reversed and
normal phase modes with mixtures of methanol/water and hexane/ethanol at
different ratios as mobile phases, respectively. Loss in resolution for some
compounds, broaden peaks and longer analysis times were observed with these last
two chromatographic elution modes. Afterwards, a comparison with the other two
CSPs was performed. A lower discrimination ability of Sepapak® 1 and
Sepapak® 2 towards all the studied flavanoids was observed. However,
Sepapak® 1 allowed the separation of naringenin enantiomers and
naringin stereoisomers in polar organic phase which were not resolved with the
other two CSPs. The nature of the chiral selector was found to be of utmost
importance for the resolution of the selected compounds. Indeed, significant
differences in enantioresolution among the three tested CSPs were observed. With
regard to the only few data reported in the literature for the resolution of
this class of compounds using polysaccharide-based CSPs by high performance
liquid chromatography (HPLC), the results obtained in this study by means of
nano-LC showed higher (R s ) values and shorter analysis time.
Graphical abstract
Graphical abstract Highlights
►
Stereoisomer separation of flavanones by nano-liquid chromatography. ► Use of
polysaccharide chiral stationary phases based on cellulose and amylose. ►
Evaluation of the CSPs in polar organic, reversed and normal elution modes. ►
Good results concerning enantioresolution, and short analysis time were
obtained.
Publication year:
2012 Source:Analytica Chimica Acta, Volume 738 Hongdeng Qiu, Abul
K. Mallik, Makoto Takafuji, Xia Liu, Shengxiang Jiang, Hirotaka Ihara In this
paper, a new imidazolium-embedded C18 stationary phase (SiImC18) for
reversed-phase high-performance liquid chromatography is described.
1-Allyl-3-octadecylimidazolium bromide ionic liquid compound having a long alkyl
chain and reactive groups was newly prepared and grafted onto
3-mercaptopropyltrimethoxysilane-modified silica via a surface-initiated
radical-chain transfer addition reaction. The SiImC18 obtained was characterized
by elemental analysis, infrared spectroscopy, thermogravimetric analysis,
diffuse reflectance infrared Fourier transform, and solid-state 13C
and 29Si cross-polarization/magic angle spinning nuclear magnetic
resonance spectroscopy. The selectivity toward polycyclic aromatic hydrocarbons
relative to that toward alkylbenzenes exhibited by SiImC18 was higher than the
corresponding selectivity exhibited by a conventional octadecyl silica (ODS)
column, which could be explained by electrostatic π–π interaction cationic
imidazolium and electron-rich aromatic rings. On the other hand, SiImC18 also
showed high selectivity for polar compounds, which was based on the multiple
interaction and retention mechanisms of this phase with different analytes.
1,6-Dinitropyrene and 1,8-dinitropyrene, which form a positional isomer pair of
dipolar compounds, were separated successfully with the SiImC18 phase. Seven
nucleosides and bases (i.e. cytidine, uracil, uridine, thymine, guanosine,
xanthosine, and adenosine) were separated using only water as the mobile phase
within 8min, which is difficult to achieve when using conventional hydrophobic
columns such as ODS. The combination of electrostatic and hydrophobic
interactions is important for the effective separation of such basic compounds
without the use of any organic additive as the eluent in the
octadecylimidazolium column.
Graphical abstract
Graphical abstract Highlights
►
Imidazolium-embedded C18 stationary phase was prepared and characterized. ►
Enhanced chromatographic selectivity was observed in SiImC18 column. ► Seven
nucleosides and bases were separated using only water as eluent within 8min. ►
Multiple-interactions induced by embedded polar imidazolium was investigated.
No comments:
Post a Comment