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Monday, 5 November 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 753 Xuemei Wang, Jiyan
Liu, Aifeng Liu, Qian Liu, Xinzhen Du, Guibin Jiang Two kinds of mesoporous
cellular foams (MCFs), including mesoporous silica materials (MCF-1) and phenyl
modified mesoporous materials (Ph-MCF-1), were synthesized and for the first
time used as fiber-coating materials for solid-phase microextraction (SPME). By
using stainless steel wire as the supporting core, four types of fibers were
prepared by sol–gel method and immobilized by epoxy-resin method. To evaluate
the performance of the home-made fibers for SPME, seven brominated flame
retardants (BFRs), including tetrabromobisphenol A (TBBPA), tetrabromobisphenol
S (TBBPS) and related compounds were selected as analytes. The main parameters
that affect the extraction and desorption efficiencies, such as extraction
temperature, extraction time, desorption time, stirring rate and ionic strength
of samples were investigated and optimized. The optimized SPME coupled with high
performance liquid chromatography (HPLC) was successfully applied to the
determination of the seven BFRs in water samples. The linearity range was from
5.0 to 1000μgL−1 for each compound except TBBPS (from 1.0 to
1000μgL−1), with the correlation coefficients (r 2)
ranging from 0.9993 to 0.9999. The limits of detection of the method were
0.4–0.9μgL−1. The relative standard deviations varied from 1.2 to
5.1% (n =5). The repeatability of fiber-to-fiber and batch-to-batch was 2.5–6.5%
and 3.2–6.7%. The recoveries of the BFRs from aqueous samples were in the range
between 86.5 and 103.6%. Compared with three commercial fibers (100μm PDMS, 85μm
PA and 65μm PDMS/DVB), the MCFs-coated fiber showed about 3.5-fold higher
extraction efficiency.
Graphical abstract
Graphical abstract Highlights
►
Two novel mesoporous cellular foams were synthesized and used as SPME coating. ►
Four SPME fibers were prepared by sol–gel technology and immobilized resin
method. ► New coating had excellent extraction ability to seven brominated flame
retardants.
Publication year:
2012 Source:Analytica Chimica Acta, Volume 753 Chad P. Satori,
Vratislav Kostal, Edgar A. Arriaga The analysis of isolated organelles is one
of the pillars of modern bioanalytical chemistry. This review describes recent
developments on the isolation and characterization of isolated organelles both
from living organisms and cell cultures. Salient reports on methods to release
organelles focused on reproducibility and yield, membrane isolation, and
integrated devices for organelle release. New developments on organelle
fractionation after their isolation were on the topics of centrifugation,
immunocapture, free flow electrophoresis, flow field-flow fractionation,
fluorescence activated organelle sorting, laser capture microdissection, and
dielectrophoresis. New concepts on characterization of isolated organelles
included atomic force microscopy, optical tweezers combined with Raman
spectroscopy, organelle sensors, flow cytometry, capillary electrophoresis, and
microfluidic devices.
Graphical abstract
Graphical abstract Highlights
►
Advancements in organelle release. ► New approaches to fractionate organelles. ►
Updates on new techniques to characterize isolated organelles.
Publication year:
2012 Source:Analytica Chimica Acta, Volume 753 Caitlin N. Rinke,
Mary R. Williams, Christopher Brown, Matthieu Baudelet, Martin Richardson,
Michael E. Sigman A method is described for performing discriminant analysis
in the presence of interfering background signal. The method is based on
performing target factor analysis on a data set comprised of contributions from
analyte(s) and interfering components. A library of data from representative
analyte classes is tested for possible contributing factors by performing
oblique rotations of the principal factors to obtain the best match, in a
least-squares sense, between test and predicted vectors. The degree of match
between the test and predicted vectors is measured by the Pearson correlation
coefficient, r, and the distribution of r for each class is determined. A
Bayesian soft classifier is used to calculate the posterior probability based on
the distributions of r for each class, which assist the analyst in assessing the
presence of one or more analytes. The method is demonstrated by analyses
performed on spectra obtained by laser induced breakdown spectroscopy (LIBS).
Single and multiple bullet jacketing transfers to steel and porcelain substrates
were analyzed to identify the jacketing materials. Additionally, the metal
surrounding bullet holes was analyzed to identify the class of bullet jacketing
that passed through a stainless steel plate. Of 36 single sample transfers, the
copper jacketed (CJ) and non-jacketed (NJ) class on porcelain had an average
posterior probability of the metal deposited on the substrate of 1.0. Metal
jacketed (MJ) bullet transfers to steel and porcelain were not detected as
successfully. Multiple transfers of CJ/NJ and CJ/MJ on the two substrates
resulted in posterior probabilities that reflected the presence of both
jacketing materials. The MJ/NJ transfers gave posterior probabilities that
reflected the presence of the NJ material, but the MJ component was mistaken for
CJ on steel, while non-zero probabilities were obtained for both CJ and MJ on
porcelain. Jacketing transfer from a bullet to steel as the projectile passed
through the steel also proved difficult to analyze. Over 50% of the samples left
insufficient transfer to be identified. Transfer from NJ and CJ jacketing was
successfully identified by posterior probabilities greater than 0.8.
Graphical abstract
Graphical abstract Highlights
► A
novel background-independent soft classification method is described. ► Target
factor analysis is combined with Bayesian decision theory. ► Target factors are
taken from a library of target analytes. ► Trace metal transfers to complex
backgrounds are analyzed by LIBS. ► The method is shown to be both conservative
and accurate.
Publication year:
2012 Source:Analytica Chimica Acta, Volume 753 Jingjing Wu, Huaqin
Chu, Zhanlong Mei, Yi Deng, Feng Xue, Lei Zheng, Wei Chen A one-step
electrochemical aptasensor using the thiol- and methylene blue- (MB-)
dual-labeled aptamer modified gold electrode for determination of ochratoxin A
(OTA) was presented in this research. The aptamer against OTA was covalently
immobilized on the surface of the electrode by the self-assembly effect and used
as recognition probes for OTA detection by the binding induced folding of the
aptamer. Under the optimal conditions, the developed electrochemical aptasensor
demonstrated a wide linear range from 0.1pgmL−1 to
1000pgmL−1 with the limit of detection (LOD) of
0.095pgmL−1, which was an extraordinary sensitivity compared with
other common methods for OTA detection. Moreover, as a practical application,
this proposed electrochemical aptasensor was used to monitor the OTA level in
red wine samples without any special pretreatment and with satisfactory results
obtained. Study results showed that this electrochemical aptasensor could be a
potential useful platform for on-site OTA measurement in real complex samples.
Graphical abstract
Graphical abstract Highlights
►
One-step electrochemical aptasensor for OTA detection. ► Rapid and
ultrasensitive OTA detection with LOD of 0.095pgmL−1 in less than
15min. ► Successful application of the electrochemical aptasensor in OTA spiked
samples. ► Providing a potential tool for on-site quality control of OTA related
pollutions.
Publication year:
2012 Source:Analytica Chimica Acta, Volume 753 Shagayegh Saadati,
Abdollah Salimi, Rahman Hallaj, Amin Rostami A novel, simple and facile layer
by layer (LBL) approach is used for modification of glassy carbon (GC) electrode
with multilayer of catalase and nanocomposite containing
1-(3-Aminopropyl)-3-methylimidazolium bromide (amine terminated ionic liquid
(NH2-IL)) and titanium nitride nanoparticles (TiNnp). First a thin layer of
NH2-IL is covalently attached to GC/TiNnp electrode using electro-oxidation
method. Then, with alternative self assemble positively charged NH2-IL and
negatively charged catalase a sensitive H2O2 biosensor is constructed, whose
response is directly correlated to the number of bilayers. The surface coverage
of active catalase per bilayer, heterogeneous electron transfer rate constant (k
s) and Michaelis–Menten constant (K M) of immobilized catalase were
3.32×10−12 molcm−2, 5.28s−1 and 1.1mM,
respectively. The biosensor shows good stability, high reproducibility, long
life-time, and fast amperometric response with the high sensitivity of
380μAmM−1 cm−2 and low detection limit of 100nM at
concentration range up to 2.1mM.
Graphical abstract
Graphical abstract Highlights
►
Catalase and amine-terminated ionic liquid were immobilized to GC/TiNnp with LBL
assembly method. ► First a thin layer of NH2-IL is covalently attached to
GC/TiNnp electrode using electro-oxidation. ► With alternative assemble of IL
and catalase with positive and negative charged, multilayer was formed. ►
Immobilized catalase shows excellent electrocatalytic activity toward H2O2
reduction. ► Biosensor response is directly correlated to the number of
bilayers.
Publication year:
2012 Source:Analytica Chimica Acta, Volume 753 Virginie Aumond,
Matthieu Waeles, Pascal Salaün, Kristoff Gibbon-Walsh, Constant M.G. van den
Berg, Pierre-Marie Sarradin, Ricardo D. Riso A rapid electrochemical
stripping chronopotentiometric procedure to determined sulfide in unaltered
hydrothermal seawater samples is presented. Sulfide is deposited at −0.25V (vs
Ag/AgCl, KCl 3M) at a vibrating gold microwire and then stripped through the
application of a reductive constant current (typically −2μA). The hydrodynamic
conditions are modulated by vibration allowing a short deposition step, which is
shown here to be necessary to minimize H2S volatilization. The limit of
detection (LOD) is 30nM after a deposition step of 7s. This LOD is in the same
range as the most sensitive cathodic voltammetric technique using a mercury drop
electrode and is well below those reported previously for other electrodes
capable of being implemented in situ.
Publication year:
2012 Source:Analytica Chimica Acta, Volume 753 Xiao Qing Yan, Qian
Jin Shen, Xiao Ran Zhao, Hai Yue Gao, Xue Pang, Wei Jun Jin For the first
time, halogen-bonding interaction is utilised in the solid phase extraction of
perfluorinated iodoalkane (PFI). Nine PFIs, as model analytes, were tested, and
analyses by UV, 19F NMR and Raman spectroscopies demonstrate that the
PFIs are extracted by a strong anion exchange (SAX) sorbent from n-hexane due to
the CI⋯Cl− halogen-bonding interactions. The results also show that
the adsorptivities of SAX for the diiodoperfluoro-alkanes (diiodo-PFIs) were
much stronger than those for the perfluoroalkyl iodides (monoiodo-PFIs).
Specifically, the recoveries for 1,6-diiodoperfluorohexane and
1,8-diiodoperfluorooctane were higher than 80% when 100mL of sample spiked with
a 5ngmL−1 analyte mixture was extracted. Interestingly, SAX had no
adsorption for hexafluorobenzene at all, which is known to be unable to form a
halogen bond with Cl−. The analytical performance of the halogen
bond-based SPE-GC–MS method for the diiodo-PFIs was also examined in soil
samples. The sorbent SAX enabled the selective extraction of four diiodo-PFIs
successfully from soil samples. The recoveries of the diiodo-PFIs extracted from
5g soil sample at the 100ngg−1 spike level were in the range of
73.2–93.8% except 26.8% for 1,2-diiodoperfluoroethane. The limit of detection
varied from 0.02 to 0.04ngg−1 in soil samples. Overall, this work
reveals the great application potential of halogen bonding in the field of solid
phase extraction to selectively extract compounds with strong halogen-bonding
abilities.
Graphical abstract
Graphical abstract Highlights
►
Halogen bonding (XB) is firstly utilised in solid phase extraction. ► The
perfluorinated iodine alkanes can be extracted by CI⋯Cl− halogen
bonding. ► The CI⋯Cl− halogen bond is well characterised by
spectroscopy methods. ► The analytes with strong halogen-bonding abilities can
be selectively extracted.
Publication year:
2012 Source:Analytica Chimica Acta, Volume 753 Xiaowei Wang, Li
Lin, Tiangang Luan, Lihua Yang, Nora F.Y. Tam A sample preparation method for
the determination of hydroxylated polycyclic aromatic hydrocarbons (OH-PAHs) in
sediment samples was developed using gas chromatography–mass spectrometry
(GC–MS). Dispersive liquid–liquid microextraction (DLLME) with derivatization
was performed following the subcritical water extraction (SWE) that provided
which was provided by accelerated solvent extraction (ASE). Several important
parameters that affected both SWE extraction and DLLME, such as the selection of
organic modifier, its volume, extraction temperature, extraction pressure and
extraction time were also investigated. High sensitivity of the hydroxylated
PAHs derivatives by N-(tert-butyldimethylsilyl)-N-methyl-trifluoroacetamide
(MTBSTFA) could be achieved with the limits of detection (LODs) ranging from
0.0139 (2-OH-nap) to 0.2334μgkg−1 (3-OH-fluo) and the relative
standard deviations (RSDs) between 2.81% (2-OH-phe) and 11.07% (1-OH-pyr).
Moreover, the proposed method was compared with SWE coupled with solid phase
extraction (SPE), and the results showed that ASE–DLLME was more promising with
recoveries ranging from 57.63% to 91.07%. The proposed method was then applied
to determine the hydroxylated metabolites of phenanthrene in contaminated
sediments produced during the degradation by two PAH-degraders isolated from
mangrove sediments.
Graphical abstract
Graphical abstract Highlights
► We
combine subcritical water extraction (SWE) with dispersive liquid–liquid
microextraction (DLLME). ► Subcritical water is used as the extraction solvent
for SWE and the sample solution for the following DLLME. ► Acetonitrile is used
as the organic modifier for SWE and disperser solvent for DLLME in succession. ►
We examine changes of OH-PAHs during the degradation by
microorganism.
Publication year:
2012 Source:Analytica Chimica Acta, Volume 753 Liting Liu, Ying
Zhang, Lei Zhang, Guoquan Yan, Jun Yao, Pengyuan Yang, Haojie Lu Although the
specific profiling of endogenous glycopeptides in serum is highly inclined
towards the discovery of disease biomarkers, studies on the endogenous
glycopeptides (glycopeptidome) have never been conducted because of several
factors. These factors include the high dynamic range of serum proteins, the
inadequacy of traditional sample preparation techniques in proteomics for
low-molecular-weight (LMW) proteins, and the relatively low abundances of
glycopeptides. Boronic acid-functionalized mesoporous silica was synthesized in
this study to overcome the limitations of the state-of-the-art methods for
glycopeptidome research. The boronic acid-functionalized mesoporous silica
exhibited excellent selectivity by analyzing glycopeptides in the mixture of
glycopeptides/non-glycopeptides at molar ratio of 1:100, extreme sensitivity
(the limit of detection was at the fmol level), good binding capacity
(40mgg−1), as well as the high post-enrichment recovery of
glycopeptides (up to 88.10%). The as-prepared material possessing both
glycopeptide-suitable pore size and glycopeptide-specific selectivity has shown
special capability for enriching the endogenous glycopeptides. Fifteen unique
glycosylation sites mapped to 15 different endogenous glycopeptides were
identified in rat serum. The established protocol revealed for the first time
the rat serum glycopeptidome.
Graphical abstract
Graphical abstract Highlights
A highly ordered boronic
acid-functionalized mesoporous silica was synthesized and applied for the
revelation of rat serum glycopeptidome for the first time. ► A highly ordered boronic acid-functionalized mesoporous
silica was synthesized. ► The as-prepared material possessed both
glycopeptide-suitable pore size and glycopeptide-specific selectivity. ► The
as-prepared material showed highly efficient ability for enrichment of
endogenous glycopeptides from serum. ► Rat serum glycopeptidome was reveled for
the first time.
Publication year:
2012 Source:Analytica Chimica Acta, Volume 753 Ying-Han Lai,
Pui-Kin So, Samual Chun-Lap Lo, Eddy Wing Yin Ng, Terence Chuen Wai Poon,
Zhong-Ping Yao A matrix-assisted laser desorption/ionization mass
spectrometry (MALDI-MS)-based method has been developed for rapid
differentiation between Panax ginseng and Panax quinquefolius, two herbal
medicines with similar chemical and physical properties but different
therapeutic effects. This method required only a small quantity of samples, and
the herbal medicines were analyzed by MALDI-MS either after a brief extraction
step, or directly on the powder form or small pieces of raw samples. The
acquired MALDI-MS spectra showed different patterns of ginsenosides and small
chemical molecules between P. ginseng and P. quinquefolius, thus allowing
unambiguous differentiation between the two Panax species based on the specific
ions, intensity ratios of characteristic ions or principal component analysis.
The approach could also be used to differentiate red ginseng or P. quinquefolius
adulterated with P. ginseng from pure P. ginseng and pure Panax quinquefolium.
The intensity ratios of characteristic ions in the MALDI-MS spectra showed high
reproducibility and enabled quantitative determination of ginsenosides in the
herbal samples and percentage of P. quinquefolius in the adulterated binary
mixture. The method is simple, rapid, robust, and can be extended for analysis
of other herbal medicines.
Graphical abstract
Graphical abstract Highlights
►
Rapid differentiation of Panax ginseng and Panax quinquefolius by MALDI-MS. ►
Direct analysis of raw herbal samples by MALDI-MS. ► Identification of
adulterated Panax quinquefolius. ► Quantitative measurements of ginsenosides and
compositions of Panax ginseng and Panax quinquefolius mixtures.
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