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Publication year:
2012 Source:Analytica Chimica Acta, Volume 745 Sandeep P.
Ravindranath, Ulhas S. Kadam, Dorothea K. Thompson, Joseph
Irudayaraj Understanding the chemical composition of biofilm matrices is
vital in different fields of biology such as surgery, dental medicine, synthetic
grafts and bioremediation. The knowledge of biofilm development, composition,
active reduction sites and remediation efficacy will help in the development of
effective solutions and evaluation of remediating approaches prior to
implementation. Surface-enhanced Raman spectroscopy (SERS) based imaging is an
invaluable tool to obtain an understanding of the remediating efficacy of
microorganisms and its role in the formation of organic and inorganic compounds
in biofilms. We demonstrate for the first time, the presence of chromate,
sulfate, nitrate and reduced trivalent chromium in soil biofilms. In addition,
we demonstrate that SERS imaging was able to validate two observations made by
previous studies on chromate/sulfate and chromate/nitrate interactions in
Shewanella oneidensis MR-1 biofilms. Additionally, we show a detailed Raman
mapping based evidence of the existence of chromate–sulfate competition for
cellular entry. Subsequently, we use Raman mapping to study the effect of
nitrate on chromate reduction. The findings presented in this paper are among
the first to report – detection of multiple metallic ions in bacterial biofilms
using intracellular SERS substrates. Such a detailed characterization of
biofilms using gold nanoislands based SERS mapping substrate can be extended to
study cellular localization of other metallic ions and chemical species of
biological and toxicological significance and their effect on reduction
reactions in bacterial biofilms.
Graphical abstract
Graphical abstract Highlights
► A
bioanalytical approach for the simultaneous analysis of chromate, sulfate and
nitrate reduction is presented. ► The uptake of gold nanoislands by the
bacterium cells using TEM and FLIM imaging. ► The study determines the
simultaneous reduction of chromate, sulfate and nitrate at single-cell level
using Raman chemical imaging. ► The chromate–sulfate, chromate–nitrate
interactions, and chromate–sulfate competition in single
bacterium.
Publication year:
2012 Source:Analytica Chimica Acta, Volume 745 Laura
Rodriguez-Lorenzo, Laura Fabris, Ramon A. Alvarez-Puebla Multiplex analysis
permits the detection of several analytical targets at the same time. This
approach may permit to draw a rapid and accurate diagnostic about the health of
an individual or an environment. Among the analytical techniques with potential
for multiplexing surface-enhanced Raman scattering (SERS) offer unique
advantages such as ultrasensitive detection down low the deconvolution times, a
unique signature containing all the vibrational information of the target
molecules, and the possibility of performing the experiments even in very
demanding environments such as natural or biological fluids. Here we review the
late advances in multiplex SERS including the direct methods, those aided by the
surface functionalization of the plasmonic nanoparticles and the use of SERS
encoded particles.
Graphical abstract
Graphical abstract Highlights
►
Multiplex SERS may be applied directly, but it is restricted due to the
complexity of real samples. ► The SERS spectrum of a given probe is equivalent
to a barcode of that chemical entity. ► The number of SERS codes is practically
unlimited. ► Bioimaging with encoded SERS particles is one of the most promising
approaches. ► SERS bioimaging has enabled the ratiometric quantification of
cancerous vs. non-cancerous cells.
Publication year:
2012 Source:Analytica Chimica Acta, Volume 745 Vanessa
Romarís-Hortas, Pilar Bermejo-Barrera, Jorge Moreda-Piñeiro, Antonio
Moreda-Piñeiro A bioavailability study based on an in vitro dialyzability
approach has been applied to assess the bio-available fractions of iodine and
bromine species from edible seaweed. Iodide, iodate, 3-iodo-tyrosine (MIT),
3,5-diiodo-tyrosine (DIT), bromide and bromate were separated by anion exchange
chromatography under a gradient elution mode (175mM ammonium nitrate plus 15%
(v/v) methanol, pH 3.8, as a mobile phase, and flow rates within the
0.5–1.5mLmin−1 range). Inductively coupled plasma-mass spectrometry
(ICP-MS) was used as a selective detector for iodine (127I) and
bromine (79Br). Low dialyzability ratios (within the 2.0–18% range)
were found for iodine species; whereas, moderate dialyzability percentages (from
9.0 to 40%) were obtained for bromine species. Iodide and bromide were the major
species found in the dialyzates from seaweed, although MIT and bromate were also
found in the dialyzates from most of the seaweed samples analysed. However, DIT
was only found in dialyzates from Wakame, Kombu, and NIES 09 (Sargasso)
certified reference material; whereas, iodate was not found in any dialyzate.
Iodine dialyzability was found to be dependent on the protein content (negative
correlation), and on the carbohydrate and dietary fibre levels (positive
correlation). However, bromine dialyzability was only dependent on the protein
amount in seaweed (negative correlation).
Graphical abstract
Graphical abstract Highlights
►
Bioavailable iodine and bromine speciation in edible seaweed were developed. ►
In vitro dialyzability was used to assess the bioavailable fractions. ► AEC
hyphenated with inductively coupled plasma-mass spectrometry was used. ► Iodide,
MIT, DIT, bromide and bromate were found in dialyzates from edible seaweed. ►
Positive correlation between bioavailability and protein contents was
found.
Publication year:
2012 Source:Analytica Chimica Acta, Volume 745 Geng-huang Wu,
Yan-fang Wu, Xi-wei Liu, Ming-cong Rong, Xiao-mei Chen, Xi Chen In this
study, an electrochemical ascorbic acid (AA) sensor was constructed based on a
glassy carbon electrode modified with palladium nanoparticles supported on
graphene oxide (PdNPs-GO). PdNPs with a mean diameter of 2.6nm were
homogeneously deposited on GO sheets by the redox reaction between PdCl4
2− and GO. Cyclic voltammetry and amperometric methods were used to
evaluate the electrocatalytic activity towards the oxidation of AA in neutral
media. Compared to a bare GC or a Pd electrode, the anodic peak potential of AA
(0.006V) at PdNPs-GO modified electrode was shifted negatively, and the large
anodic peak potential separation (0.172V) of AA and dopamine (DA), which could
contribute to the synergistic effect of GO and PdNPs, was investigated. A
further amperometric experiment proved that the proposed sensor was capable of
sensitive and selective sensing of AA even in the presence of DA and uric acid.
The modified electrode exhibited a rapid response to AA within 5s and the
amperometric signal showed a good linear correlation to AA concentration in a
broad range from 20μM to 2.28mM with a correlation coefficient of R =0.9991.
Moreover, the proposed sensor was applied to the determination of AA in vitamin
C tablet samples. The satisfactory results obtained indicated that the proposed
sensor was promising for the development of novel electrochemical sensing for AA
determination.
Graphical abstract
Graphical abstract Highlights
►
PdNPs with a mean diameter of 2.6nm were homogeneously deposited on GO. ► The
proposed sensor exhibited a rapid amperometric response to AA within 5s. ► Good
selectivity, wide linear range, low detection limit for AA.
Publication year:
2012 Source:Analytica Chimica Acta, Volume 745 Jeanette M. Van
Emon, Jane C. Chuang An efficient and reliable analytical method was
developed for the sensitive and selective quantification of pyrethroid
pesticides (PYRs) in house dust samples. The method is based on selective
pressurized liquid extraction (SPLE) of the dust-bound PYRs into dichloromethane
(DCM) with analysis by gas chromatography/mass spectrometry. Various adsorbents
and combinations of extraction solvents and temperatures were evaluated to
achieve a high-throughput sample preparation that eliminates the post-extraction
cleanup step. The final method used sulfuric acid-impregnated silica (acid
silica) and neutral silica together in the extraction cell with the dust sample
to provide both extraction and cleanup simultaneously. The optimal ratio of
dust/acid silica/silica was 1:0.8:8. The extraction was performed at 2000psi, at
100°C with DCM for 5min in three cycles. Method precision and accuracy were
evaluated by the analysis of triplicate aliquots of the dust samples and the
samples fortified with the target PYRs. The accuracy measured as the recoveries
of the PYRs in the fortified samples ranged from 85% to 120%. The precision
measured as the relative standard deviation of replicate samples was within
±25%. The SPLE method was applied to 20 house dust samples collected from
households that participated in two field studies regarding exposures to
pesticides and other pollutants. Similar concentrations of target PYRs were
obtained for the SPLE and a stepwise extraction/cleanup procedure. The SPLE
procedure reduces organic solvent consumption and increases the sample
throughput when compared with a traditional stepwise extraction and cleanup
procedure. This study demonstrates that the SPLE procedure can be applied to
complex dust matrices for analysis of PYRs for large scale exposure or
environmental monitoring studies.
Graphical abstract
Graphical abstract Highlights
► A
selective pressurized liquid extraction (SPLE) method was developed for
dust-bound pyrethroid residues. ► The SPLE compared favorably with a multi-step
extraction and cleanup procedure. ► House dust samples from two exposure studies
were analyzed using the SPLE method. ► The SPLE procedure could be applied to a
large sample load generated by a monitoring study.
Publication year:
2012 Source:Analytica Chimica Acta, Volume 745 Saeed Nojavan, Ahmad
Pourahadi, Saied Saeed Hosseiny Davarani, Amin Morteza-Najarian, Mojtaba
Beigzadeh Abbassi This study has performed on electromembrane extraction
(EME) of some zwitterionic compounds based on their acidic and basic properties.
High performance liquid chromatography (HPLC) equipped with UV detection was
used for determination of model compounds. Cetirizine (CTZ) and mesalazine (MS)
were chosen as model compounds, and each of them was extracted from acidic (as a
cation) and basic (as an anion) sample solutions, separately. 1-Octanol and
2-nitrophenyl octylether (NPOE) were used as the common supported liquid
membrane (SLM) solvents. EME parameters, such as extraction time, extraction
voltage and pH of donor and acceptor solutions were studied in details for
cationic and anionic forms of each model compound and obtained results for two
ionic forms (cationic and anionic) of each compound were compared together.
Results showed that zwitterionic compounds could be extracted in both cationic
and anionic forms. Moreover, it was found that the extraction of anionic form of
each model compound could be done in low voltages when 1-octanol was used as the
SLM solvent. Results showed that charge type was not highly effective on the
extraction efficiency of model compounds whereas the position of charge within
the molecule was the key parameter. In optimized conditions, enrichment factors
(EF) of 27–60 that corresponded to recoveries ranging from 39 to 86% were
achieved.
Graphical abstract
Graphical abstract Highlights
►
This study has performed on electromembrane extraction of zwitterionic
compounds. ► Zwitterionic compounds could be extracted from both acidic and
basic solutions. ► Extraction efficiency of cationic species of CTZ was higher
than anionic species. ► Position of charge within the CTZ was an effective
parameter on the extraction. ► Chemistry of SLM solvent was important more than
the magnitude of applied voltage.
Publication year:
2012 Source:Analytica Chimica Acta, Volume 745 Paula Vera, Blanca
Uliaque, Elena Canellas, Ana Escudero, Cristina Nerín Adhesives are often
responsible for off-flavors in food in contact with packaging. The aim of this
investigation was to identify by GC–O–MS the odorous compounds in five different
types of adhesive (hotmelt, vinyl acetate ethylene, starch, polyvinyl acetate
and acrylic) used in food packaging. In order to obtain a substantial number of
compounds, they were extracted by two complementary extraction methods: HS-SPE
and HS-SPME. Fifteen minutes extraction time using PDMS fiber for hotmelt
adhesive and DVD/CAR/PDMS fiber for the other adhesives were the best conditions
for defining a representative solvent-free adhesive extract using a rapid and
simple D-GC–O technique. Thirty-three compounds were identified by GC–O–MS.
These include butyric acid, acetic acid, methyl butyrate, 1-butanol and nonanal,
which were present in most of the adhesives under study producing cheesy,
rancid, sour, medicinal and green aromas, respectively. The concentrations were
determined, the most abundant compound being acetic acid with concentrations
from 22.9 to 8930μgg−1 of adhesive.
Graphical abstract
Graphical abstract Highlights
►
Off-odor in adhesives have been identified and analytical protocol has been
established. ► Individual compounds responsable for off-odor have been
separated, identified and quantified. ► SPE and HS-SPME are compared for
extraction of odorous compounds. ► Five different types of adhesives in
multilayer food packaging materials have been studied.
Publication year:
2012 Source:Analytica Chimica Acta, Volume 745 Rupesh K. Mishra,
George Istamboulie, Sunil Bhand, Jean-Louis Marty Among known pesticide
groups, organophosphates (OPs) have grasped attention due to their hazardous
nature and their applications as pesticides and chemical weapons. This work
presents the development of cost-effective column based biosensor for
detoxification of OPs in water and milk. Enzyme phosphotriesterase (PTE) was
immobilized on an activated Sepharose 4B via covalent coupling using an Omnifit
glass column. Three different OPs, ethyl paraoxon (EPOx), malaoxon (MAO) and
chlorpyriphos-oxon (CPO) were spiked in water and milk to test the
detoxification of OPs. Mixtures of these pesticides were also tested to check
the cumulative detoxification in the real samples. The efficiency of
detoxification was evaluated using a highly sensitive acetylcholinesterase
(AChE) B394 biosensor based flow system. The column conditions were optimized
for the detoxification studied. The method was shown to be promising when we
tested real milk samples spiked with OPs. Detoxification obtained in milk was up
to 86% whereas in water, 100% detoxification was obtained.
Graphical abstract
Graphical abstract Highlights
►
Present work demonstrates the detoxification of OPs at low level. ► This is the
first report of OPs detoxification in milk using PTE. ► PTE reacts rapidly with
OPs and hydrolyzes within few minutes. ► Detoxification of OPs using PTE was
evaluated using flow based biosensor.
Publication year:
2012 Source:Analytica Chimica Acta, Volume 745 Jeannette J.
Łucejko, Magdalena Zborowska, Francesca Modugno, Maria P. Colombini, Włodzimierz
Prądzyński The macromolecular complexity of wood limits the possibility of
obtaining complete chemical information on its alteration in archaeological
objects. This paper compares the results obtained in the characterisation of the
components of archaeological wood by a classical wet chemical method and by an
instrumental method based on pyrolysis in presence of hexamethyldisilazane
coupled with gas chromatography/mass spectrometry, Py(HMDS)–GC/MS. We compare
the results obtained with the two methods quantitatively. This enables us to
evaluate the efficiency of Py(HMDS)–GC/MS in assessing the chemical composition
and the state of conservation of degraded wood. The material analysed consisted
of reference sound wood and waterlogged wood from the Żółte historical site,
located on a small island on Lake Zarańskie in Poland. The samples are from the
remains of settlements dating to a period between the 9th and the 12th centuries
AD. The results obtained by Py(HMDS)–GC/MS analysis are consistent in the
determination of the level of degradation of archaeological wood with the
results obtained using traditional techniques. The pyrolysis method is faster,
reproducible, and reveals not only the amount but also the quality of the wood
constituents, needing a much smaller sample.
Graphical abstract
Graphical abstract Highlights
► We
compare wet chemical analysis and Py(HMDS)–GC/MS in the characterisation of
archaeological wood. ► We compare the two methods quantitatively. ► We evaluate
the efficiency of Py(HMDS)–GC/MS in assessing the state of wood conservation. ►
We characterise samples of waterlogged wood from the historical Żółte site in
Poland.
Publication year:
2012 Source:Analytica Chimica Acta, Volume 745 Zhengqing Liu,
Shaopu Liu, Pengfei Yin, Youqiu He A novel fluorescent probe for
Cu2+ determination based on the fluorescence quenching of glyphosate
(Glyp)-functionalized quantum dots (QDs) was firstly reported. Glyp had been
used to modify the surface of QDs to form Glyp-functionalized QDs following the
capping of thioglycolic acid on the core–shell CdTe/CdS QDs. Under the optimal
conditions, the response was linearly proportional to the concentration of
Cu2+ between 2.4×10−2 μgmL−1 and
28μgmL−1, with a detection limit of 1.3×10−3
μgmL−1 (3δ). The Glyp-functionalized QDs fluorescent probe offers
good sensitivity and selectivity for detecting Cu2+. The fluorescent
probe was successfully used for the determination of Cu2+ in
environmental samples. The mechanism of reaction was also discussed.
Graphical abstract
Graphical abstract Highlights
Glyphosate (Glyp) had been used
to modify the surface of CdTe/CdS QDs, resulting in the enhancement of
fluorescence intensity. The Glyp-functionalized QDs fluorescent probe offers
good sensitivity and selectivity for detecting Cu2+ based on the
fluorescence quenching. ► Water soluble CdTe/CdS
quantum dots capped with glyphosate were firstly synthesized. ► The fluorescence
of the Glyp-functionalized QDs was quenched by copper ion. ► A new fluorescent
sensor for copper ion was developed based on the prepared QDs. ► The sensor
exhibited high sensitivity and good selectivity for copper ion.
Publication year:
2012 Source:Analytica Chimica Acta, Volume 745 Petra Vukosav,
Marina Mlakar, Vladislav Tomišić A detailed study of iron (III)–citrate
speciation in aqueous solution (θ =25°C, I c =0.7molL−1) was carried
out by voltammetric and UV–vis spectrophotometric measurements and the obtained
data were used for reconciled characterization of iron (III)–citrate complexes.
Four different redox processes were registered in the voltammograms: at 0.1V
(pH=5.5) which corresponded to the reduction of iron(III)–monocitrate species
(Fe:cit=1:1), at about −0.1V (pH=5.5) that was related to the reduction of FeL2
5−, FeL2H4− and FeL2H2 3− complexes, at −0.28V
(pH=5.5) which corresponded to the reduction of polynuclear iron(III)–citrate
complex(es), and at −0.4V (pH=7.5) which was probably a consequence of
Fe(cit)2(OH) x species reduction. Reversible redox process at −0.1V allowed for
the determination of iron(III)–citrate species and their stability constants by
analyzing E p vs. pH and E p vs. [L4−] dependence. The UV–vis spectra
recorded at varied pH revealed four different spectrally active species: FeLH
(log β =25.69), FeL2H2 3− (log β =48.06), FeL2H4− (log β
=44.60), and FeL2 5− (log β =38.85). The stability constants obtained
by spectrophotometry were in agreement with those determined electrochemically.
The UV–vis spectra recorded at various citrate concentrations (pH=2.0) supported
the results of spectrophotometric–potentiometric titration.
Graphical abstract
Graphical abstract Highlights
►
Combination voltammetry-spectophotometry best portrayed Fe–citrate speciation in
aqueous solution. ► 4 redox processes of Fe(III)–citrate species were
registered: at 0.1, −0.1, −0.28 and −0.4V. ► Biochemically most important
Fe(III)–citrate mononuclear species, were described. ► log β FeLH = 25.69 ,
log β FeL 2 H 2 = 48.06 , log β FeL 2 H = 44.60 , log β FeL 2
= 38.85 .
Publication year:
2012 Source:Analytica Chimica Acta, Volume 745 Davinson Pezo,
Beatriz Navascués, Jesús Salafranca, Cristina Nerín Ethyl Lauroyl Arginate
(LAE) is a cationic tensoactive compound, soluble in water, with a wide activity
spectrum against moulds and bacteria. LAE has been incorporated as antimicrobial
agent into packaging materials for food contact and these materials require to
comply with the specific migration criteria. In this paper, one analytical
procedure has been developed and optimized for the analysis of LAE in food
simulants after the migrations tests. It consists of the formation of an ionic
pair between LAE and the inorganic complex Co(SCN)4 2− in aqueous
solution, followed by a liquid–liquid extraction in a suitable organic solvent
and further UV–Vis absorbance measurement. In order to evaluate possible
interferences, the ionic pair has been also analyzed by high performance liquid
chromatography with UV–Vis detection. Both procedures provided similar
analytical characteristics, with linear ranges from 1.10 to
25.00mgkg−1, linearity higher than 0.9886, limits of detection and
quantification of 0.33 and 1.10mgkg−1, respectively, accuracy better
than 1% as relative error and precision better than 3.6% expressed as RSD.
Optimization of analytical techniques, thermal and chemical stability of LAE, as
well as migration kinetics of LAE from experimental active packaging are
reported and discussed.
Graphical abstract
Graphical abstract Highlights
►
Ethyl Lauroyl Arginate (LAE) has been incorporated as antimicrobial agent into
active food packaging materials. ► Ionic pair formation-based analytical methods
have been developed and applied for LAE determination at mgkg−1
level. ► UV–Vis spectrophotometry and HPLC have been used. ► LAE stability and
migration kinetics tests to aqueous food simulants have been assessed. ► One of
the prototypes of active films is a very promising as antimicrobial active
packaging for improving the shelf life of foodstuffs.
Publication year:
2012 Source:Analytica Chimica Acta, Volume 745 Xi Liu, Jun-Jian
Xiang, Yong Tang, Xiao-Li Zhang, Qiang-Qiang Fu, Jun-Hui Zou, YueHe Lin An
immunochromatographic assay (ICA) using gold nanoparticles coated with
monoclonal antibody (McAb) for the detection of chromium ions (Cr) in water and
serum samples was developed, optimized and validated. Gold nanoparticles coated
with affinity-purified monoclonal antibodies against isothiocyanobenzyl-EDTA
(iEDTA)-chelated Cr3+ were used as the detecting reagent in this
completive immunoassay-based one-step test strip. The ICA was investigated to
measure chromium speciation (Cr3+ and Cr6+ ions) in water
samples. Chromium standard samples of 0–80ngmL−1 in water were
determined by the test strips. The results showed that the visual lowest
detection limit (LDL) of the test strip was 50.0ngmL−1. A portable
colorimetric lateral flow reader was used for the quantification of Cr. The
results indicated that the linear range of the ICA with colorimetric detection
was 5–80ngmL−1. The ICA was also validated for the detection of
chromium ions in serum samples. The test trips showed high stability in that
they could be stored at 37°C for at least 12 weeks without significant loss of
activity. The test strip also showed good selectivity for Cr detection with
negligible interference from other heavy metals. Because of its low cost and
short testing time (within 5min), the test strip is especially suitable for
on-site large-scale screening of Cr-polluted water samples, biomonitoring of Cr
exposure, and many other field applications.
Graphical abstract
Graphical abstract Highlights
► An
immunochromatography assay (ICA) is the first time applied for Cr detection. ►
The ICA combine with a colorimetric reader is developed for quantification of
Cr. ► The pretreatment helps to measure chromium speciation in water and serum
samples.
Publication year:
2012 Source:Analytica Chimica Acta, Volume 745 Jingjin Zhao,
Liangliang Zhang, Chunfei Chen, Jianhui Jiang, Ruqin Yu Cancer is one of the
most serious and lethal diseases around the world. Its early detection has
become a challenging goal. To address this challenge, we developed a novel
sensing platform using aptamer and RNA polymerase-based amplification for the
detection of cancer cells. The assay uses the aptamer as a capture probe to
recognize and bind the tumor marker on the surface of the cancer cells, forming
an aptamer-based sandwich structure for collection of the cells in the
microplate wells, and uses SYBR Green II dye as a tracer to produce strong
fluorescence signal. The tumor marker interacts first with the recognition
probes which were composed of the aptamer and single-stranded T7 RNA polymerase
promoter. Then, the recognition probe hybridized with template probes to form a
double-stranded T7 RNA polymerase promoter. This dsDNA region is extensively
transcribed by T7 RNA polymerase to produce large amounts of RNAs, which are
easily monitored using the SYBR Green II dye and a standard fluorometer,
resulting in the amplification of the fluorescence signal. Using MCF-7 breast
cancer cell as the model cell, the present sensing platform showed a linear
range from 5.0×102 to 5.0×106 cellsmL−1 with a
detection limit of 5.0×102 cellsmL−1. This work suggested
a strategy to use RNA signal amplification combining aptamer recognition to
develop a highly sensitive and selective method for cancer cells detection.
Graphical abstract
Graphical abstract Highlights
►
The sensor used aptamer for target cell recognition. ► This sensor used RNA
polymerase-based isothermal amplification method. ► This sensing platform also
performed a satisfactory result in the cell media. ► This method can be further
expanded to screen more kinds of tumor cells by altering the related aptamers. ►
The sensor is high sensitivity, excellent selectivity and small volume of
sample.
Publication year:
2012 Source:Analytica Chimica Acta, Volume 745 Sandeep P.
Ravindranath, Ulhas S. Kadam, Dorothea K. Thompson, Joseph
Irudayaraj Understanding the chemical composition of biofilm matrices is
vital in different fields of biology such as surgery, dental medicine, synthetic
grafts and bioremediation. The knowledge of biofilm development, composition,
active reduction sites and remediation efficacy will help in the development of
effective solutions and evaluation of remediating approaches prior to
implementation. Surface-enhanced Raman spectroscopy (SERS) based imaging is an
invaluable tool to obtain an understanding of the remediating efficacy of
microorganisms and its role in the formation of organic and inorganic compounds
in biofilms. We demonstrate for the first time, the presence of chromate,
sulfate, nitrate and reduced trivalent chromium in soil biofilms. In addition,
we demonstrate that SERS imaging was able to validate two observations made by
previous studies on chromate/sulfate and chromate/nitrate interactions in
Shewanella oneidensis MR-1 biofilms. Additionally, we show a detailed Raman
mapping based evidence of the existence of chromate–sulfate competition for
cellular entry. Subsequently, we use Raman mapping to study the effect of
nitrate on chromate reduction. The findings presented in this paper are among
the first to report – detection of multiple metallic ions in bacterial biofilms
using intracellular SERS substrates. Such a detailed characterization of
biofilms using gold nanoislands based SERS mapping substrate can be extended to
study cellular localization of other metallic ions and chemical species of
biological and toxicological significance and their effect on reduction
reactions in bacterial biofilms.
Graphical abstract
Graphical abstract Highlights
► A
bioanalytical approach for the simultaneous analysis of chromate, sulfate and
nitrate reduction is presented. ► The uptake of gold nanoislands by the
bacterium cells using TEM and FLIM imaging. ► The study determines the
simultaneous reduction of chromate, sulfate and nitrate at single-cell level
using Raman chemical imaging. ► The chromate–sulfate, chromate–nitrate
interactions, and chromate–sulfate competition in single
bacterium.
Publication year:
2012 Source:Analytica Chimica Acta, Volume 745 Laura
Rodriguez-Lorenzo, Laura Fabris, Ramon A. Alvarez-Puebla Multiplex analysis
permits the detection of several analytical targets at the same time. This
approach may permit to draw a rapid and accurate diagnostic about the health of
an individual or an environment. Among the analytical techniques with potential
for multiplexing surface-enhanced Raman scattering (SERS) offer unique
advantages such as ultrasensitive detection down low the deconvolution times, a
unique signature containing all the vibrational information of the target
molecules, and the possibility of performing the experiments even in very
demanding environments such as natural or biological fluids. Here we review the
late advances in multiplex SERS including the direct methods, those aided by the
surface functionalization of the plasmonic nanoparticles and the use of SERS
encoded particles.
Graphical abstract
Graphical abstract Highlights
►
Multiplex SERS may be applied directly, but it is restricted due to the
complexity of real samples. ► The SERS spectrum of a given probe is equivalent
to a barcode of that chemical entity. ► The number of SERS codes is practically
unlimited. ► Bioimaging with encoded SERS particles is one of the most promising
approaches. ► SERS bioimaging has enabled the ratiometric quantification of
cancerous vs. non-cancerous cells.
Publication year:
2012 Source:Analytica Chimica Acta, Volume 745 Vanessa
Romarís-Hortas, Pilar Bermejo-Barrera, Jorge Moreda-Piñeiro, Antonio
Moreda-Piñeiro A bioavailability study based on an in vitro dialyzability
approach has been applied to assess the bio-available fractions of iodine and
bromine species from edible seaweed. Iodide, iodate, 3-iodo-tyrosine (MIT),
3,5-diiodo-tyrosine (DIT), bromide and bromate were separated by anion exchange
chromatography under a gradient elution mode (175mM ammonium nitrate plus 15%
(v/v) methanol, pH 3.8, as a mobile phase, and flow rates within the
0.5–1.5mLmin−1 range). Inductively coupled plasma-mass spectrometry
(ICP-MS) was used as a selective detector for iodine (127I) and
bromine (79Br). Low dialyzability ratios (within the 2.0–18% range)
were found for iodine species; whereas, moderate dialyzability percentages (from
9.0 to 40%) were obtained for bromine species. Iodide and bromide were the major
species found in the dialyzates from seaweed, although MIT and bromate were also
found in the dialyzates from most of the seaweed samples analysed. However, DIT
was only found in dialyzates from Wakame, Kombu, and NIES 09 (Sargasso)
certified reference material; whereas, iodate was not found in any dialyzate.
Iodine dialyzability was found to be dependent on the protein content (negative
correlation), and on the carbohydrate and dietary fibre levels (positive
correlation). However, bromine dialyzability was only dependent on the protein
amount in seaweed (negative correlation).
Graphical abstract
Graphical abstract Highlights
►
Bioavailable iodine and bromine speciation in edible seaweed were developed. ►
In vitro dialyzability was used to assess the bioavailable fractions. ► AEC
hyphenated with inductively coupled plasma-mass spectrometry was used. ► Iodide,
MIT, DIT, bromide and bromate were found in dialyzates from edible seaweed. ►
Positive correlation between bioavailability and protein contents was
found.
Publication year:
2012 Source:Analytica Chimica Acta, Volume 745 Geng-huang Wu,
Yan-fang Wu, Xi-wei Liu, Ming-cong Rong, Xiao-mei Chen, Xi Chen In this
study, an electrochemical ascorbic acid (AA) sensor was constructed based on a
glassy carbon electrode modified with palladium nanoparticles supported on
graphene oxide (PdNPs-GO). PdNPs with a mean diameter of 2.6nm were
homogeneously deposited on GO sheets by the redox reaction between PdCl4
2− and GO. Cyclic voltammetry and amperometric methods were used to
evaluate the electrocatalytic activity towards the oxidation of AA in neutral
media. Compared to a bare GC or a Pd electrode, the anodic peak potential of AA
(0.006V) at PdNPs-GO modified electrode was shifted negatively, and the large
anodic peak potential separation (0.172V) of AA and dopamine (DA), which could
contribute to the synergistic effect of GO and PdNPs, was investigated. A
further amperometric experiment proved that the proposed sensor was capable of
sensitive and selective sensing of AA even in the presence of DA and uric acid.
The modified electrode exhibited a rapid response to AA within 5s and the
amperometric signal showed a good linear correlation to AA concentration in a
broad range from 20μM to 2.28mM with a correlation coefficient of R =0.9991.
Moreover, the proposed sensor was applied to the determination of AA in vitamin
C tablet samples. The satisfactory results obtained indicated that the proposed
sensor was promising for the development of novel electrochemical sensing for AA
determination.
Graphical abstract
Graphical abstract Highlights
►
PdNPs with a mean diameter of 2.6nm were homogeneously deposited on GO. ► The
proposed sensor exhibited a rapid amperometric response to AA within 5s. ► Good
selectivity, wide linear range, low detection limit for AA.
Publication year:
2012 Source:Analytica Chimica Acta, Volume 745 Jeanette M. Van
Emon, Jane C. Chuang An efficient and reliable analytical method was
developed for the sensitive and selective quantification of pyrethroid
pesticides (PYRs) in house dust samples. The method is based on selective
pressurized liquid extraction (SPLE) of the dust-bound PYRs into dichloromethane
(DCM) with analysis by gas chromatography/mass spectrometry. Various adsorbents
and combinations of extraction solvents and temperatures were evaluated to
achieve a high-throughput sample preparation that eliminates the post-extraction
cleanup step. The final method used sulfuric acid-impregnated silica (acid
silica) and neutral silica together in the extraction cell with the dust sample
to provide both extraction and cleanup simultaneously. The optimal ratio of
dust/acid silica/silica was 1:0.8:8. The extraction was performed at 2000psi, at
100°C with DCM for 5min in three cycles. Method precision and accuracy were
evaluated by the analysis of triplicate aliquots of the dust samples and the
samples fortified with the target PYRs. The accuracy measured as the recoveries
of the PYRs in the fortified samples ranged from 85% to 120%. The precision
measured as the relative standard deviation of replicate samples was within
±25%. The SPLE method was applied to 20 house dust samples collected from
households that participated in two field studies regarding exposures to
pesticides and other pollutants. Similar concentrations of target PYRs were
obtained for the SPLE and a stepwise extraction/cleanup procedure. The SPLE
procedure reduces organic solvent consumption and increases the sample
throughput when compared with a traditional stepwise extraction and cleanup
procedure. This study demonstrates that the SPLE procedure can be applied to
complex dust matrices for analysis of PYRs for large scale exposure or
environmental monitoring studies.
Graphical abstract
Graphical abstract Highlights
► A
selective pressurized liquid extraction (SPLE) method was developed for
dust-bound pyrethroid residues. ► The SPLE compared favorably with a multi-step
extraction and cleanup procedure. ► House dust samples from two exposure studies
were analyzed using the SPLE method. ► The SPLE procedure could be applied to a
large sample load generated by a monitoring study.
Publication year:
2012 Source:Analytica Chimica Acta, Volume 745 Saeed Nojavan, Ahmad
Pourahadi, Saied Saeed Hosseiny Davarani, Amin Morteza-Najarian, Mojtaba
Beigzadeh Abbassi This study has performed on electromembrane extraction
(EME) of some zwitterionic compounds based on their acidic and basic properties.
High performance liquid chromatography (HPLC) equipped with UV detection was
used for determination of model compounds. Cetirizine (CTZ) and mesalazine (MS)
were chosen as model compounds, and each of them was extracted from acidic (as a
cation) and basic (as an anion) sample solutions, separately. 1-Octanol and
2-nitrophenyl octylether (NPOE) were used as the common supported liquid
membrane (SLM) solvents. EME parameters, such as extraction time, extraction
voltage and pH of donor and acceptor solutions were studied in details for
cationic and anionic forms of each model compound and obtained results for two
ionic forms (cationic and anionic) of each compound were compared together.
Results showed that zwitterionic compounds could be extracted in both cationic
and anionic forms. Moreover, it was found that the extraction of anionic form of
each model compound could be done in low voltages when 1-octanol was used as the
SLM solvent. Results showed that charge type was not highly effective on the
extraction efficiency of model compounds whereas the position of charge within
the molecule was the key parameter. In optimized conditions, enrichment factors
(EF) of 27–60 that corresponded to recoveries ranging from 39 to 86% were
achieved.
Graphical abstract
Graphical abstract Highlights
►
This study has performed on electromembrane extraction of zwitterionic
compounds. ► Zwitterionic compounds could be extracted from both acidic and
basic solutions. ► Extraction efficiency of cationic species of CTZ was higher
than anionic species. ► Position of charge within the CTZ was an effective
parameter on the extraction. ► Chemistry of SLM solvent was important more than
the magnitude of applied voltage.
Publication year:
2012 Source:Analytica Chimica Acta, Volume 745 Paula Vera, Blanca
Uliaque, Elena Canellas, Ana Escudero, Cristina Nerín Adhesives are often
responsible for off-flavors in food in contact with packaging. The aim of this
investigation was to identify by GC–O–MS the odorous compounds in five different
types of adhesive (hotmelt, vinyl acetate ethylene, starch, polyvinyl acetate
and acrylic) used in food packaging. In order to obtain a substantial number of
compounds, they were extracted by two complementary extraction methods: HS-SPE
and HS-SPME. Fifteen minutes extraction time using PDMS fiber for hotmelt
adhesive and DVD/CAR/PDMS fiber for the other adhesives were the best conditions
for defining a representative solvent-free adhesive extract using a rapid and
simple D-GC–O technique. Thirty-three compounds were identified by GC–O–MS.
These include butyric acid, acetic acid, methyl butyrate, 1-butanol and nonanal,
which were present in most of the adhesives under study producing cheesy,
rancid, sour, medicinal and green aromas, respectively. The concentrations were
determined, the most abundant compound being acetic acid with concentrations
from 22.9 to 8930μgg−1 of adhesive.
Graphical abstract
Graphical abstract Highlights
►
Off-odor in adhesives have been identified and analytical protocol has been
established. ► Individual compounds responsable for off-odor have been
separated, identified and quantified. ► SPE and HS-SPME are compared for
extraction of odorous compounds. ► Five different types of adhesives in
multilayer food packaging materials have been studied.
Publication year:
2012 Source:Analytica Chimica Acta, Volume 745 Rupesh K. Mishra,
George Istamboulie, Sunil Bhand, Jean-Louis Marty Among known pesticide
groups, organophosphates (OPs) have grasped attention due to their hazardous
nature and their applications as pesticides and chemical weapons. This work
presents the development of cost-effective column based biosensor for
detoxification of OPs in water and milk. Enzyme phosphotriesterase (PTE) was
immobilized on an activated Sepharose 4B via covalent coupling using an Omnifit
glass column. Three different OPs, ethyl paraoxon (EPOx), malaoxon (MAO) and
chlorpyriphos-oxon (CPO) were spiked in water and milk to test the
detoxification of OPs. Mixtures of these pesticides were also tested to check
the cumulative detoxification in the real samples. The efficiency of
detoxification was evaluated using a highly sensitive acetylcholinesterase
(AChE) B394 biosensor based flow system. The column conditions were optimized
for the detoxification studied. The method was shown to be promising when we
tested real milk samples spiked with OPs. Detoxification obtained in milk was up
to 86% whereas in water, 100% detoxification was obtained.
Graphical abstract
Graphical abstract Highlights
►
Present work demonstrates the detoxification of OPs at low level. ► This is the
first report of OPs detoxification in milk using PTE. ► PTE reacts rapidly with
OPs and hydrolyzes within few minutes. ► Detoxification of OPs using PTE was
evaluated using flow based biosensor.
Publication year:
2012 Source:Analytica Chimica Acta, Volume 745 Jeannette J.
Łucejko, Magdalena Zborowska, Francesca Modugno, Maria P. Colombini, Włodzimierz
Prądzyński The macromolecular complexity of wood limits the possibility of
obtaining complete chemical information on its alteration in archaeological
objects. This paper compares the results obtained in the characterisation of the
components of archaeological wood by a classical wet chemical method and by an
instrumental method based on pyrolysis in presence of hexamethyldisilazane
coupled with gas chromatography/mass spectrometry, Py(HMDS)–GC/MS. We compare
the results obtained with the two methods quantitatively. This enables us to
evaluate the efficiency of Py(HMDS)–GC/MS in assessing the chemical composition
and the state of conservation of degraded wood. The material analysed consisted
of reference sound wood and waterlogged wood from the Żółte historical site,
located on a small island on Lake Zarańskie in Poland. The samples are from the
remains of settlements dating to a period between the 9th and the 12th centuries
AD. The results obtained by Py(HMDS)–GC/MS analysis are consistent in the
determination of the level of degradation of archaeological wood with the
results obtained using traditional techniques. The pyrolysis method is faster,
reproducible, and reveals not only the amount but also the quality of the wood
constituents, needing a much smaller sample.
Graphical abstract
Graphical abstract Highlights
► We
compare wet chemical analysis and Py(HMDS)–GC/MS in the characterisation of
archaeological wood. ► We compare the two methods quantitatively. ► We evaluate
the efficiency of Py(HMDS)–GC/MS in assessing the state of wood conservation. ►
We characterise samples of waterlogged wood from the historical Żółte site in
Poland.
Publication year:
2012 Source:Analytica Chimica Acta, Volume 745 Zhengqing Liu,
Shaopu Liu, Pengfei Yin, Youqiu He A novel fluorescent probe for
Cu2+ determination based on the fluorescence quenching of glyphosate
(Glyp)-functionalized quantum dots (QDs) was firstly reported. Glyp had been
used to modify the surface of QDs to form Glyp-functionalized QDs following the
capping of thioglycolic acid on the core–shell CdTe/CdS QDs. Under the optimal
conditions, the response was linearly proportional to the concentration of
Cu2+ between 2.4×10−2 μgmL−1 and
28μgmL−1, with a detection limit of 1.3×10−3
μgmL−1 (3δ). The Glyp-functionalized QDs fluorescent probe offers
good sensitivity and selectivity for detecting Cu2+. The fluorescent
probe was successfully used for the determination of Cu2+ in
environmental samples. The mechanism of reaction was also discussed.
Graphical abstract
Graphical abstract Highlights
Glyphosate (Glyp) had been used
to modify the surface of CdTe/CdS QDs, resulting in the enhancement of
fluorescence intensity. The Glyp-functionalized QDs fluorescent probe offers
good sensitivity and selectivity for detecting Cu2+ based on the
fluorescence quenching. ► Water soluble CdTe/CdS
quantum dots capped with glyphosate were firstly synthesized. ► The fluorescence
of the Glyp-functionalized QDs was quenched by copper ion. ► A new fluorescent
sensor for copper ion was developed based on the prepared QDs. ► The sensor
exhibited high sensitivity and good selectivity for copper ion.
Publication year:
2012 Source:Analytica Chimica Acta, Volume 745 Petra Vukosav,
Marina Mlakar, Vladislav Tomišić A detailed study of iron (III)–citrate
speciation in aqueous solution (θ =25°C, I c =0.7molL−1) was carried
out by voltammetric and UV–vis spectrophotometric measurements and the obtained
data were used for reconciled characterization of iron (III)–citrate complexes.
Four different redox processes were registered in the voltammograms: at 0.1V
(pH=5.5) which corresponded to the reduction of iron(III)–monocitrate species
(Fe:cit=1:1), at about −0.1V (pH=5.5) that was related to the reduction of FeL2
5−, FeL2H4− and FeL2H2 3− complexes, at −0.28V
(pH=5.5) which corresponded to the reduction of polynuclear iron(III)–citrate
complex(es), and at −0.4V (pH=7.5) which was probably a consequence of
Fe(cit)2(OH) x species reduction. Reversible redox process at −0.1V allowed for
the determination of iron(III)–citrate species and their stability constants by
analyzing E p vs. pH and E p vs. [L4−] dependence. The UV–vis spectra
recorded at varied pH revealed four different spectrally active species: FeLH
(log β =25.69), FeL2H2 3− (log β =48.06), FeL2H4− (log β
=44.60), and FeL2 5− (log β =38.85). The stability constants obtained
by spectrophotometry were in agreement with those determined electrochemically.
The UV–vis spectra recorded at various citrate concentrations (pH=2.0) supported
the results of spectrophotometric–potentiometric titration.
Graphical abstract
Graphical abstract Highlights
►
Combination voltammetry-spectophotometry best portrayed Fe–citrate speciation in
aqueous solution. ► 4 redox processes of Fe(III)–citrate species were
registered: at 0.1, −0.1, −0.28 and −0.4V. ► Biochemically most important
Fe(III)–citrate mononuclear species, were described. ► log β FeLH = 25.69 ,
log β FeL 2 H 2 = 48.06 , log β FeL 2 H = 44.60 , log β FeL 2
= 38.85 .
Publication year:
2012 Source:Analytica Chimica Acta, Volume 745 Davinson Pezo,
Beatriz Navascués, Jesús Salafranca, Cristina Nerín Ethyl Lauroyl Arginate
(LAE) is a cationic tensoactive compound, soluble in water, with a wide activity
spectrum against moulds and bacteria. LAE has been incorporated as antimicrobial
agent into packaging materials for food contact and these materials require to
comply with the specific migration criteria. In this paper, one analytical
procedure has been developed and optimized for the analysis of LAE in food
simulants after the migrations tests. It consists of the formation of an ionic
pair between LAE and the inorganic complex Co(SCN)4 2− in aqueous
solution, followed by a liquid–liquid extraction in a suitable organic solvent
and further UV–Vis absorbance measurement. In order to evaluate possible
interferences, the ionic pair has been also analyzed by high performance liquid
chromatography with UV–Vis detection. Both procedures provided similar
analytical characteristics, with linear ranges from 1.10 to
25.00mgkg−1, linearity higher than 0.9886, limits of detection and
quantification of 0.33 and 1.10mgkg−1, respectively, accuracy better
than 1% as relative error and precision better than 3.6% expressed as RSD.
Optimization of analytical techniques, thermal and chemical stability of LAE, as
well as migration kinetics of LAE from experimental active packaging are
reported and discussed.
Graphical abstract
Graphical abstract Highlights
►
Ethyl Lauroyl Arginate (LAE) has been incorporated as antimicrobial agent into
active food packaging materials. ► Ionic pair formation-based analytical methods
have been developed and applied for LAE determination at mgkg−1
level. ► UV–Vis spectrophotometry and HPLC have been used. ► LAE stability and
migration kinetics tests to aqueous food simulants have been assessed. ► One of
the prototypes of active films is a very promising as antimicrobial active
packaging for improving the shelf life of foodstuffs.
Publication year:
2012 Source:Analytica Chimica Acta, Volume 745 Xi Liu, Jun-Jian
Xiang, Yong Tang, Xiao-Li Zhang, Qiang-Qiang Fu, Jun-Hui Zou, YueHe Lin An
immunochromatographic assay (ICA) using gold nanoparticles coated with
monoclonal antibody (McAb) for the detection of chromium ions (Cr) in water and
serum samples was developed, optimized and validated. Gold nanoparticles coated
with affinity-purified monoclonal antibodies against isothiocyanobenzyl-EDTA
(iEDTA)-chelated Cr3+ were used as the detecting reagent in this
completive immunoassay-based one-step test strip. The ICA was investigated to
measure chromium speciation (Cr3+ and Cr6+ ions) in water
samples. Chromium standard samples of 0–80ngmL−1 in water were
determined by the test strips. The results showed that the visual lowest
detection limit (LDL) of the test strip was 50.0ngmL−1. A portable
colorimetric lateral flow reader was used for the quantification of Cr. The
results indicated that the linear range of the ICA with colorimetric detection
was 5–80ngmL−1. The ICA was also validated for the detection of
chromium ions in serum samples. The test trips showed high stability in that
they could be stored at 37°C for at least 12 weeks without significant loss of
activity. The test strip also showed good selectivity for Cr detection with
negligible interference from other heavy metals. Because of its low cost and
short testing time (within 5min), the test strip is especially suitable for
on-site large-scale screening of Cr-polluted water samples, biomonitoring of Cr
exposure, and many other field applications.
Graphical abstract
Graphical abstract Highlights
► An
immunochromatography assay (ICA) is the first time applied for Cr detection. ►
The ICA combine with a colorimetric reader is developed for quantification of
Cr. ► The pretreatment helps to measure chromium speciation in water and serum
samples.
Publication year:
2012 Source:Analytica Chimica Acta, Volume 745 Jingjin Zhao,
Liangliang Zhang, Chunfei Chen, Jianhui Jiang, Ruqin Yu Cancer is one of the
most serious and lethal diseases around the world. Its early detection has
become a challenging goal. To address this challenge, we developed a novel
sensing platform using aptamer and RNA polymerase-based amplification for the
detection of cancer cells. The assay uses the aptamer as a capture probe to
recognize and bind the tumor marker on the surface of the cancer cells, forming
an aptamer-based sandwich structure for collection of the cells in the
microplate wells, and uses SYBR Green II dye as a tracer to produce strong
fluorescence signal. The tumor marker interacts first with the recognition
probes which were composed of the aptamer and single-stranded T7 RNA polymerase
promoter. Then, the recognition probe hybridized with template probes to form a
double-stranded T7 RNA polymerase promoter. This dsDNA region is extensively
transcribed by T7 RNA polymerase to produce large amounts of RNAs, which are
easily monitored using the SYBR Green II dye and a standard fluorometer,
resulting in the amplification of the fluorescence signal. Using MCF-7 breast
cancer cell as the model cell, the present sensing platform showed a linear
range from 5.0×102 to 5.0×106 cellsmL−1 with a
detection limit of 5.0×102 cellsmL−1. This work suggested
a strategy to use RNA signal amplification combining aptamer recognition to
develop a highly sensitive and selective method for cancer cells detection.
Graphical abstract
Graphical abstract Highlights
►
The sensor used aptamer for target cell recognition. ► This sensor used RNA
polymerase-based isothermal amplification method. ► This sensing platform also
performed a satisfactory result in the cell media. ► This method can be further
expanded to screen more kinds of tumor cells by altering the related aptamers. ►
The sensor is high sensitivity, excellent selectivity and small volume of
sample.
