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
Friday, 29 June 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:Talanta Georgi Stoev, Yue Xuan, Milena Peycheva,
Michaela Scigelova Applications of high resolution mass spectrometry (HRMS)
in food safety and residue analysis have increased remarkably over the last few
years. The high resolution detection of ions reportedly enhances the assay
selectivity but quantitative assessment of HRMS contribution to the assay
selectivity has not yet been undertaken. We devised a method to assess the
impact of instrument resolution on the probability that a spectral assignment to
a given compound was made in error. The method allows for evaluating the quality
of a spectral assignment based on resolution and the number of fragmentation
stages. It thus provides a firm basis for comparing analytical methods performed
on very different mass spectrometric instrumental platforms as well as in the
context of the current regulatory framework.
Graphical abstract
Graphical abstract Highlights
► High
mass resolution impacts positively on the confidence of confirmation. ► Method
quantifies the contribution of the resolution to assay selectivity. ► Method
allows evaluation of regulatory framework identification
criteria
Publication year:
2012 Source:Talanta Isabela Maia Toaldo, Gabriel Zandonadi Gamba,
Lidia Almeida Picinin, Gabriel Rubensam, Rodrigo Hoff, Marilde
Bordignon-Luiz A simplified procedure for simultaneous quantification of
ceftiofur (CEF), fluoroquinolone (FQ) and sulfonamide (SA) antibacterials in
bovine milk was developed. The reverse-phase liquid chromatography (RP-LC)
multiclass method for analysis of eleven distinct compounds, from three
antibacterial classes, was validated in line with Commission Decision
2002/657/EC. Confirmation of the analytes identities was performed by
electrospray mass spectrometry detection. The analytes were extracted from milk
matrix by liquid-liquid extraction with acidified ultrapure water and directly
analyzed in the chromatograph. The SA compounds were pre-column derivatized with
fluorescamine for fluorescence detection. The method provided good results
regarding the analytical parameters of linearity, selectivity, sensitivity,
precision, recovery, decision limit (CCα), detection capability (CCβ), limit of
detection (LOD), limit of quantification (LOQ), stability and robustness.
Analytes were extracted by liquid-liquid extraction in the fortified matrix and
the compounds identity was confirmed by their precursor ion and fragments
through tandem mass spectrometry analysis. Additionally, milk samples from two
state capitals in the South Region of Brazil were analyzed by both the
quantitative and confirmatory methods. The validation process showed correlation
coefficients (r 2 ) greater than 0.98 for all the analytes, with
recovery rates up to 98% for all the studied drugs. LOD and LOQ limits ranged
from 8.0 to 20.0ngmL−1 and 10.0 to 32.0ngmL−1,
demonstrating good specificity of the method. The intra-day and inter-day
precisions for all the analytes were below or equal to 7.40 and 10.13,
respectively. The studied antibacterials were not detected in milk samples. The
developed method represents an efficient alternative for multi-residue analysis
in milk, being suitable and especially viable for monitoring in developing
countries.
Highlights
► Sulfonamides, fluoroquinolones and ceftiofur were
determined in milk. ► Acidified water was efficient for extraction without
further clean up procedure. ► Validation results showed great performance for
the LC method. ► Analyzed samples from Brazil showed no detection.► A feasible
alternative to monitor residues in milk was developed.
Publication year:
2012 Source:Talanta Alzira Yamasaki, João A.B.P. Oliveira, Armando
C. Duarte, M.Teresa S.R. Gomes Copper and lead in wine were quantified by
anodic stripping voltammetry (ASV), performed onto the gold electrode of a
piezoelectric quartz crystal. Both current or mass changes could be used as
analytical signals, without a statistical difference in the results (α=0.05).
However, the plot of mass vs. potential provided an in depth understanding of
the electrochemical processes and allowed studying adsorption phenomena. Copper
interaction with fructose is an example of a process which was not possible to
ignore by observing the mass change on the gold electrode of the piezoelectric
quartz crystal.
Publication year:
2012 Source:Talanta Phimpha Soisungnoen, Rodjana Burakham, Supalax
Srijaranai A rapid and sensitive method using two preconcentration
techniques, dispersive liquid-liquid microextraction (DLLME) followed by
reversed electrode polarity stacking mode (REPSM) was developed for the analysis
of five organophosphorus pesticides (OPPs) by micellar electrokinetic
chromatography (MEKC). Parameters that affect the efficiency of the extraction
in DLLME and preconcentration by REPSM, such as the kind and volume of the
extraction and disperser solvents, salt addition, sample matrix and injection
time were investigated and optimized. Under the optimum conditions, the
enrichment factors were obtained in the range from 477 to 635. The linearity of
the method for parathion, azinphos and fenitrithion was in the range of
20–1000ngmL−1, and for malathion and diazinon in the range of
50–1000ngmL−1, with correlation coefficients (r 2) ranging
from 0.9931 to 0.9992. The limits of detecton (LODs) at a signal-to-noice ratio
of 3 ranged from 3 to 15ngmL−1. The relative recoveries of five OPPs
from water samples at spiking levels of 20 and 200ngmL−1 for
parathion, azinphos and fenitrithion, and 50 and 500ngmL−1 for
malathion and diazinon, were 69.5-103%. The proposed method provided high
enrichment factors, good precision and accuracy with a short analysis time.
Publication year:
2012 Source:Talanta Zdeňka Jarolímová, Přemysl Lubal, Viktor
Kanický An analytical method for the determination of the composition of
renal stones by capillary isotachophoresis with conductometric detection was
developed. Using different leading/terminating electrolyte systems, the
qualitative and quantitative analysis of organic compounds (urate, xanthate,
oxalate) and inorganic ions (phosphate, Ca2+, Mg2+,
Na+,, NH4 +) species commonly present in mixed renal
stones in three separate steps can be carried out with limits of detection about
10μmol/L. The developed method was validated by the analysis of real samples and
can be used for urinary calculi classification. In addition, it was verified
that this method can also be employed for the determination of the above
mentioned analytes in some other samples (bones, teeth) concerning apatite
biominerals (fluoro-, carbonate-, chloro-apatite).
Highlights
► Cationic and anionic analysis by capillary
isotachophoresis with conductivity detection. ► The robust and fast method was
developed for analysis of biominerals. ► Application for
qualitative/quantitative analysis of uric stones, bones and
teeth.
Publication year:
2012 Source:Talanta Shijuan Zhang, Jinmao You, Guoying Zhou, Chunli
Li, Yourui Suo A new labeling reagent for fatty acids, 1-(9H-carbazol-9-yl)
propan-2-yl-methanesulfonate (CPMS), has been synthesized and successfully
applied to the HPLC determination of fatty acids in traditional Chinese herb
Notopterygium forbesii Boiss. The reaction of CPMS with fatty acids could
proceed easily and quickly in the presence of K2CO3 catalyst within 30min. The
derivatives exhibit excellent fluorescence property with excitation and emission
wavelengths of 293nm and 360nm, respectively. The 34 derivatives of fatty acids
were separated on a BDS C8 reversed-phase column with gradient elution. Good
linear correlations were observed for all fatty acids with correlation
coefficients of >0.996. The detection limits at a signal-to-noise ratio of 3
were in the range of 0.032–0.312μgg–1. Free fatty acids in the roots,
stem, leaves and petioles of Notopterygium forbesii Boiss from different places
was analyzed by the developed method. This is the first time that the fatty
acids composition of Notopterygium forbesii Boiss has been reported. This method
also shows powerful potential for the trace analysis of fatty acids or other
carboxylic acids from complex samples.
Highlights
► A new labeling reagent for fatty acids has been
synthesized. ► Fatty acids composition of Notopterygium forbesii Boiss was
reported for the first time. ► Sensitivity was much higher than the often used
GC methods.
Publication year:
2012 Source:Talanta K. Volkan Özdokur, Levent Pelit, Hasan Ertaş,
Suna Timur, F. Nil Ertaş Present paper describes the results of a novel
method which combines the Headspace (HS) preconcentration of the analyte on the
electrode prior to the voltammetric analysis. Thereafter, the method was called
HS-Voltammetry. The performance of the method was tested upon using an
electroactive and volatile molecule phenol molecule which gives an oxidation
peak at conventional electrodes. In this study, a glassy carbon electrode was
modified with polypyrrole by electropolymerization and then, the electrode was
placed over the solution in a sealed vial heated gently on a hotplate with a
stirrer for phenol determination. By controlling the thickness of polymeric
coating and optimizing preconcentration parameters such as vial pH and
temperature, stirring rate and exposure time, a very consistent (5.2% at
5.0×10−7 M) fraction of the analyte can be extracted during a
predetermined time. The oxidation peak current at 0.8V depended linearly on the
phenol concentration over a wide range (3 orders of magnitude). The detection
limit was estimated as 7.0×10−8 M at 60°C (S/N=3) which is well below
the limit set by the European Community for phenols in wastewaters (ca.
5×10−6 M). The effect of other phenolic compounds was also examined
and it was shown that head space preconcentration eliminated the interference of
nonvolatile phenolic acids studied. For volatile phenolic compounds, the
selectivity can be maintained in cases when isolated peaks are obtained for each
component. The proposed method has been applied successfully for the
determination of phenol in artificial wastewater and recovery percentage was
calculated as 93%.
Highlight
► Voltammetry was combined with the advantageous of
headspace sampling. ► Detection limit for phenol was improved with HS
accumulation. ► The interference of non-volatile components was eliminated by HS
sampling. ► Phenol and 2,4-dichlorophenol can be determined simultaneously by
this means
Publication year:
2012 Source:Talanta Vo Thanh Phuong Nguyen, Virginie Piersoel,
Tarik El Mahi A sensitive and specific ion-pair reversed-phase high
performance liquid chromatography (HPLC) method for urinary iodine analysis is
described. This method is based on pulsed amperometric detection (PAD) using a
silver working electrode (HPLC-PAD), which improves peak shape, electrode
stability as well as linearity and reproducibility. A two-step extraction
process consisting of solid phase extraction (SPE) and liquid-liquid extraction
with dichloromethane was added in order to improve sample purification which is
essential with the use of PAD. Treated samples were eluted on a C18 column,
using a phosphate buffer containing ion-pairing reagent tetrabutylammonium and
5% MeOH. The calibration standard curves were linear up to 500µg/L and
within-run and between–run coefficients of variation (CVs) were <6% with the
quantification limit fixed at 6µg/L. Accuracy, expressed as recovery, ranged
from 94 to 104%. Comparison with the Technicon AutoAnalyzer acid digestion (AA)
method resulted in a high correlation (r=0.9916). Due to a low quantification
limit and high sample throughput, the proposed technique appears suitable for
both epidemiological and clinical follow-up studies.
Highlights
► We developed a HPLC-PAD method for determining
iodide concentration in urine. ► Pulsed amperometric detection improves peak
shape and electrode stability. ► Two extraction steps for sample purification
are necessary. ► This method is sensitive, selective, precise and accurate. ►
The method is effective for urinary iodine determination.
Publication year:
2012 Source:Talanta Yi Li, Liu Deng, Chunyan Deng, Zhou Nie,
Minghui Yang, Shihui Si A novel electrochemical aptasensor involving quantum
dots-coated silica nanospheres (QDs/Si) and the screen-printed gold electrodes
(SPGE) was developed for the detection of thrombin. The screen-printed electrode
with several advantages including low cost, versatility, miniaturization, and
mechanical regeneration after each measurement cycle were employed. On the other
hand, the gold nanoparticles (AuNPs) were electrodeposited on the surface of
SPGE to obtain the AuNPs/SPGE. And this sandwich format
(Apt/thrombin/Apt−QDs/Si) was fixed on the AuNPs/SPGE to fabricate the
electrochemical aptasensor. The bound CdTe QDs were dissolved in an
acid-dissolution step and were detected by electrochemical stripping analysis.
The proposed aptasensor has excellent performance such as high sensitivity, good
selectivity and analytical application in real samples. The combination of
nanoparticles with the screen-printed electrode is favorable for amplifying
electrochemical signals, and useful for large-scale fabrication of the
electrochemical aptasensors, which would lay a potential foundation for the
development of the electrochemical aptasensor.
Highlights
► We fabricated the electrochemical aptasensor with
simplicity and high sensitivity. ► Gold nanoparticles were electrodeposited onto
the screen-printed electrode. ► The bound QDs were dissolved in an
acid-dissolution step and were detected. ► Nanoparticles may be favorable for
amplifying electrochemical signals. ► The screen-printed electrode was useful
for the large fabrication of the aptasensor.
Publication year:
2012 Source:Talanta Kailou Zhao, Li Yang, Xuejiao Wang, Quan Bai,
Fan Yang, Fei Wang We have explored a novel dual-function stationary phase
which combines both strong cation exchange (SCX) and hydrophobic interaction
chromatography (HIC) characteristics. The novel dual-function stationary phase
is based on porous and spherical silica gel functionalized with a ligand
containing sulfonic and benzyl groups capable of electrostatic and hydrophobic
interaction functionalities, which displays HIC character in a high salt
concentration, and IEC character in a low salt concentration in mobile phase
employed. As a result, it can be employed to separate proteins with SCX and HIC
modes, respectively. The resolution and selectivity of the dual-function
stationary phase were evaluated under both HIC and SCX modes with standard
proteins and can be comparable to that of conventional IEC and HIC columns. More
than 96% of mass and bioactivity recoveries of proteins can be achieved in both
HIC and SCX modes, respectively. The results indicated that the novel
dual-function column could replace two individual SCX and HIC columns for
protein separation. Mixed retention mechanism of proteins on this dual-function
column based on stoichiometric displacement theory (SDT) in LC was investigated
to find the optimal balance of the magnitude of electrostatic and hydrophobic
interactions between protein and the ligand on the silica surface in order to
obtain high resolution and selectivity for protein separation. In addition, the
effects of the hydrophobicity of the ligand of the dual-function packings and pH
of the mobile phase used on protein separation were also investigated in detail.
The results show that the ligand with suitable hydrophobicity to match the
electrostatic interaction is very important to prepare the dual-function
stationary phase, and a better resolution and selectivity can be obtained at pH
6.5 in SCX mode. Therefore, the dual-function column can replace two individual
SCX and HIC columns for protein separation and be used to set up two-dimensional
liquid chromatography with a single column (2DLC-1C), which can also be employed
to separate three kinds of active proteins completely, such as lysozyme,
ovotransferrin and ovalbumin from egg white. The result is very important not
only to the development of new 2DLC technology with a single column for
proteomics, but also to recombinant protein drug production for saving column
expense and simplifying the process in biotechnology.
Highlights
► We explored a bifunctional column with a ligand
containing sulfo and benzyl groups. ► This column can provide two operation
modes (HIC and SCX). ► High resolution and selectivity are obtained in both SCX
and HIC modes, respectively. ► This column can replace two corresponding single
mode (SCX and HIC mode) columns. ► Based on this bifunctional column, 2DLC was
established using only a single column.
Publication year:
2012 Source:Talanta Cédric Delporte, Thierry Franck, Caroline
Noyon, Damien Dufour, Alexandre Rousseau, Philippe Madhoun, Jean-Marc Desmet,
Didier Serteyn, Martine Raes, Joëlle Nortier, Michel Vanhaeverbeek, Nicole
Moguilevsky, Jean Nève, Luc Vanhamme, Pierre Van Antwerpen, Karim Zouaoui
Boudjeltia A high degree of uremia is common in patients with end-stage renal
disease and has been linked to the development of chronic inflammation and
cardiovascular diseases. In conditions where transplantation is not possible,
uremia can be reduced by hemodialysis although the repeated interventions have
been implicated in loss of renal function, partially as a result of chronic
inflammation and/or oxidative stress processes. In this context, it has been
suggested that myeloperoxidase (MPO) can contribute to the oxidative stress
during hemodialysis and to the cardiovascular risk. Protein damages due to MPO
activity have never been assessed during hemodialysis although two of its
reaction products, 3-chlorotyrosine and homocitrulline, are of interest. Indeed,
the first one is a specific product of MPO activity and the formation of the
second one could be catalyzed by MPO. In order to analyze these products in
plasma proteins, a total hydrolysis method followed by liquid chromatography
mass spectrometry analysis was developed. Different conditions of hydrolysis
were tested and the optimized procedure was assessed for complete hydrolysis and
artifactual chlorination. Finally, the method was used for analyzing
3-chlorotyrosine and homocitrulline in plasma proteins during a hemodialysis
session in fifteen patients and data were related to measurements of MPO
concentration and activity. Both increases in MPO activity and protein-bound
3-chlorotyrosine were observed, highlighting the involvement of MPO in oxidative
stress during hemodialysis and further demonstrating the link between
hemodialysis and cardiovascular diseases.
Highlights
► Simultaneous detection of protein-bound
3-chlorotyrosine and homocitrulline. ► Rapid protein acid hydrolysis assisted by
microwave oven. ► Method applied to a clinical situation: patients undergoing
hemodialysis. ► Myeloperoxidase activity increases during hemodialysis. ►
3-chlorotyrosine but not homocitrulline increases during
hemodialysis
Publication year:
2012 Source:Talanta Vikash Kumar, Amrita Chatterjee, Mainak
Banerjee A turn-on fluorescent probe for the detection of nitrite ion in
water is developed based on diazotization reaction of the amino group of the
probe in an acidic solution (pH 1). The probe responds selectively to nitrite
ion over various other anions with a turn-on type fluorogenic change from
colorless to orange by the formation of rhodamine B via an analyte triggered
fragmentation process. The fluorescence titration is complete within 1h with 1
equiv of nitrite ion. The probe is highly efficient, cost-effective and shows a
detection limit of 4.6ppb.
Highlights
► A rhodamine-based fluorescent probe is developed
for the detection of nitrite ions. ► The probe is highly selective to nitrite
ions in presence of many other anions. ► The fluorogenic detection level of
nitrite is found to be as low as 4.6ppb. ► The probe was successfully used for
detection of NO2¯ level in several real samples.
Publication year:
2012 Source:Talanta Jie Zhou, Qian Lu, Ying Tong, Wei Wei, Songqin
Liu A hairpin molecular beacon tagged with carboxyfluorescein in combination
with graphene oxide as a quencher reagent was used to detect the DNA damage by
chemical reagents. The fluorescence of molecular beacon was quenched sharply by
graphene oxide; while in the presence of its complementary DNA the quenching
efficiency decreased because their hybridization prevented the strong
adsorbability of molecular beacon on graphene oxide. If the complementary DNA
was damaged by a chemical reagent and could not form intact duplex structure
with molecular beacon, more molecular beacon would adsorb on graphene oxide
increasing the quenching efficiency. Thus, damaged DNA could be detected based
on different quenching efficiencies afforded by damaged and intact complementary
DNA. The damage effects of chlorpyrifos-methyl and three metabolites of styrene
such as mandelieaeids, phenylglyoxylieaeids and epoxystyrene on DNA were studied
as models. The method for detection of DNA damage was reliable, rapid and simple
compared to the biological methods.
Highlights
► DNA damage induced by several chemicals was
detected by a hairpin MB based on FRET. ► The method was rapid, simple, reliable
and sensitive. ► The method can be used to detect damaged DNA induced by other
reagents or factors.
Publication year:
2012 Source:Talanta Geng Leng, Hui Yin, Shaobo Li, Yong Chen,
Dezhong Dan A simple and fast solvent microextraction method termed
vortex-assisted liquid-liquid microextraction (VALLME) coupled with
high-performance liquid chromatography-vapor generation atomic fluorescence
spectrometry (HPLC-CVAFS) has been developed for the trace analysis of
methylmercury (MeHg+), ethylmercury (EtHg+) and inorganic
mercury (Hg2+) in sediment samples. Carbon tetrachloride was used as
collecting solvent for the extraction of mercury species from sediment by a
vortex-assisted extraction. In VALLME, 100μL 1% (m/v) L-Cysteine were used as
extraction solvent and were injected into 4mL carbon tetrachloride. The
extraction solvent dispersed into carbon tetrachloride under vigorously shaking
by a vortex agitator. The fine droplets could extract mercury species within few
minutes because of the shorter diffusion distance and larger specific surface
area. After centrifugation, the floating extractant phase restored its initial
single microdrop shape and was used for HPLC-CVAFS analysis. The parameters
affecting the extraction efficiency of the proposed VALLME such as extraction
solvent, vortex time, volumes of extraction solvent and salt addition etc. were
investigated. Under the optimum conditions, linearity was found in the
concentration range from 0.1 to 25ng g−1 for MeHg+, 0.2 to
65ng g−1 for EtHg+, and 0.1 to 30ng g−1 for
Hg2+. Coefficients of determination (R2) ranged from
0.9938 to 0.9972. The limits of detection (LODs, signal-to-noise ratio (S/N)=3)
were 0.028ng g−1 for MeHg+, 0.057ng g−1 for
EtHg+, and 0.029ng g−1 for Hg2+.
Reproducibility and recoveries were assessed by testing a series of 6 sediment
samples, which were spiked with different concentration levels. Finally, the
proposed method was successfully applied in analyses of real nature sediment
samples. In this work, VALLME was applied to the extraction of mercury species
in sediment samples for the first time. Using L-Cys as extraction solvent, the
extraction process is sensitive and environmentally friendly and could be
achieved within 3min.
Highlights
► VALLME was for the first time applied for the
extraction of mercury species in sediment.► Using L-Cys as extraction solvent,
the extraction is sensitive and environmentally friendly.► The extraction
process is achieved within 3min.
Publication year:
2012 Source:Talanta Fang Liu, Yan Zhang, Shenguang Ge, Juanjuan Lu,
Jinghua Yu, Xianrang Song, Su Liu A highly sensitive electrochemiluminescence
(ECL) immunosensor for the detection of prostate specific antigen (PSA) was
designed using biofunctionalized magnetic graphene nanosheets (G@Fe3O4) as
immunosensing probes and CdTe quantum dots coated silica nanospheres (Si/QDs) as
signal amplification labels. In this work, a sandwich-type immunosensor was
fabricated, which was assembled on the surface of indium tin oxide glass (ITO).
The analyte was detected in a home-made flow injection ECL (FI-ECL) cell through
the immunosensor. Owning to the signal amplification of G@Fe3O4 composite and
Si/QDs, the ECL measurement showed a great increase in detection signals
compared with the unamplified method. Under optimal conditions, a wide detection
range (0.003–50ngmL−1) and low detection limit
(0.72pgmL−1) were obtained through the sandwich-type immunosensor.
The proposed strategy successfully demonstrated a reproducible, specific, and
potent method that can be expanded to detect other proteins.
Highlights
► A sandwich-type electrochemluminence immunosensor
was fabricated. ► Magnetic graphene nanosheets were synthesized as immunosensing
probes. ► CdTe quantum dots coated silica nanospheres were used to amplify
signals. ► A home-made injection electrochemluminence cell was used as reaction
chamber.
Publication year:
2012 Source:Talanta Chunxiao Liu, Xinglei Zhang, Saijin Xiao, Bin
Jia, Shasha Cui, Jianbo Shi, Ning Xu, Xi Xie, Haiwei Gu, Huanwen Chen A
sensitive approach, based on semi-quantitative measurement of the characteristic
fragments in multi-stage extractive electrospray ionization mass spectrometry
(EESI-MSn), was developed for fast detection of trace levels of lead
in aqueous liquids including mineral water, lake water, tap water, energy
drinks, soft drinks, beer, orange juice, and tea. A disodium
ethylene-diamine-tetraacetic acid (EDTA) aqueous solution was electrosprayed to
produce negatively charged primary ions which then intersected the neutral
sample plume to generate anions of EDTA-Pb(II) complexes. The charged
EDTA-Pb(II) complexes were characterized with multistage collision induced
dissociation (CID) experiments. The limit of detection (LOD) using
EESI-MS3 was estimated to be at the level of 10–13 g/mL
for directly detecting lead in many of these samples. The linear dynamic range
was higher than 2 orders of magnitude. A single sample analysis could be
completed within 2min with reasonable semi-quantitative performance, e.g.,
relative standard deviations (RSDs) for deionized water were 4.6%-7.6% during 5
experimental runs (each of them had 10 repeated measurements). Coca-cola and
Huiyuan orange juice, representative beverage samples with complex matrices,
generated recovery rates of 91.5% and 129%, respectively. Our experimental data
demonstrated that EESI-MS is a useful tool for the fast detection of lead in
various solutions, and EESI-MS showed promises for fast screening of
lead-contaminated aqueous liquid samples.
Highlights
► EESI can directly detect lead in complex samples.
► EESI can semi-quantitatively measure the lead concentration. ► EESI may have
wide applications for food security and environmental science
SP Scientific, and Praxair Inc., headquartered in Danbury, CT, are pleased to
announce the expansion of their collaborative relationship to commercialize
Praxair's ControLyo™ Nucleation on Demand Technology.
The original agreement, signed in October 2010, gave SP Scientific the
exclusive, global rights to commercialize the technology on Development
Lyophilizers <1.0 m. The Praxair ControLyo™ Technology was implemented on SP
Scientific's Lyostar 3 Freeze Dryer in December 2010. The expansion of the
agreement allows SP Scientific to also equip its clinical, pilot and production
dryers (Benchmark series and Hull Production Dryers) with the ControLyo™
Technology. Additionally, the agreement calls for the transfer of technology to
allow SP Scientific to retrofit existing Pilot and Production units in the
field, regardless of the original manufacturer.
"This is a major step in SP's strategy of technology leadership in
lyophilization," states Chuck Grant, CEO for SP Scientific. "Given
the ability to offer the technology from development through scale-up to
production, SP Scientific is ideally positioned to be the supplier of choice
for ControLyo™ Technology."
"Praxair is pleased to extend our existing agreement to cover the full
range of lyophilizers offered to the industry by SP Scientific, " said
Rich Jarrett, Global Director of Marketing and Business Development for
Praxair. "Praxair's ControLyo™ Technology has seen quick industry adoption
with SP Scientific's Lyostar 3 FreezeDryer and we look forward to providing the
industry with nucleation control at all production levels."
ControLyo™ Technology offers many benefits to the pharmaceutical industry
including: vial-to-vial uniformity, reduced cycle times, reduced protein
aggregation and better conformance to the Food and Drug Administration's
Process Analytical Technology (PAT) initiative.
Fluidigm Corporation has announced that it can now offer unrestricted sales of
its digital PCR and other advanced technology to customers interested in
pursuing research and product development into the prenatal health and
non-invasive prenatal diagnostics fields, as well as other fields. This
enhanced freedom to operate comes as a result of the ending of the
collaboration agreement previously reported in the company's filings with the
Securities and Exchange Commission between Fluidigm and Novartis Vaccines &
Diagnostics, Inc.
Under the collaboration agreement, Fluidigm granted an exclusive option to its
technology in specific areas of prenatal health and diagnostics, and Fluidigm
could not sell its products or services in these fields, other than in some cases
for research applications. This option has expired unexercised. Also, while the
details of the collaboration remain confidential, Fluidigm can confirm that it
successfully achieved all of its technical feasibility milestones in the first
phase of the collaboration and, accordingly, received all milestone payments.
The re-opening of previously restricted fields of use for Fluidigm products and
access to significant product enhancements represent exciting opportunities for
Fluidigm's customer base.
A number of Fluidigm's customers had expressed concerns over their ability to
freely operate in the fields of prenatal health and non-invasive prenatal
diagnostics in view of the collaboration agreement. Some potential customers
chose to pursue alternative options because of this uncertainty. "With the
termination of this agreement, highly valuable intellectual property rights in
non-invasive prenatal diagnostics and digital PCR, which had been exclusively
optioned under the agreement, now revert back to Fluidigm. We are open for
business without restriction in all fields," said Gajus Worthington,
Fluidigm President and Chief Executive Officer.
Fluidigm can now fully pursue all market opportunities with customers
interested in researching and developing products in all fields, including
prenatal health and non-invasive prenatal diagnostics. "We appreciate that
there are significant market opportunities in these areas and there is
substantial customer interest. We look forward to helping these customers achieve
their research and development objectives," Worthington added.
With the termination of the collaboration, Fluidigm's customers may experience
other, more direct benefits. Chief among them is unrestricted access to the
company's prototype 200,000-chambered digital PCR chip with associated
instrumentation and software developed under several on-going collaborative
efforts. The company can now commercialize this much higher density chip, for
which it has experimentally demonstrated both very high sensitivity and
reproducibility.
Elsevier has announced the SciVerse ScienceDirect redesigned article page, with a new layout including a navigational pane and an optimized reading middle pane (see the video below).
The Article of the Future project- an ongoing initiative aiming to revolutionize the traditional format of the academic paper in regard to three key elements: presentation, content and context.
Given that only ten years ago paper copies of journals were the main way for publishers to deliver content, how do you think scientific content will be delivered (format, type of content, delivery system, etc) ten years from now?
A $25 Amazon voucher is on offer for the best or most imaginative forecast. Post your replies below. (Deadline July 31st, 2012).
The Kavli Nanoscience Institute
(KNI) at Caltech, USA and Oxford Instruments are excited to announce their
joint Seminar and Workshop entitled Etch Tech 2012, taking place 16th-17th
July. The event is open to all those people working in industry and academia
with an interest in recent progress in research and development, plus future
trends in the fabrication and application of micro & nano structures and
devices.
Topics include Advances in Deep
RIE / MEMS; OpSIS, Single Digit Nanoscale Fabrication; Optical and Electrical
Probes; Silicon Nanowires and Novel Etch Techniques; Diamond Etching and
Nanoscale Applications of ALD.
Following an introduction by
Oxford Instruments Managing Director Dan Ayres, there will be talks from
invited guest speakers, senior KNI Caltech and Oxford Instruments Plasma
Technology specialists.
Speakers from Caltech, include
Professor Oskar Painter, Executive Officer for Applied Physics and Materials
Science and Co-Director, Kavli Nanoscience Institute, Caltech; Andrei
Faraon Assistant Professor of Applied Physics and Materials Science; Rassul Karabalin,
Senior Research Scientist, Condensed Matter Physics at Caltech; Sameer Walavalkar, Postoctoral
Scholar in Physics, Caltech. Guest speakers include Dr Deirdre Olynick,
Nanofabrication Facility, Lawrence Berkeley National Lab and Professor Michael
Hochberg, Electrical and Chemical Engineering, University of Delaware.
As a leading manufacturer of
plasma processing systems, Oxford Instruments has Process Applications and
Technology teams who are highly experienced and qualified, with many years
experience. They will offer talks on various aspects of plasma etch and
deposition processing, and on day two will be running tutorial sessions,
allowing plenty of time for delegates to ask questions. Following this there
will be tours of the Kavli Nanoscience Institute’s cleanroom facility.
Comments Prof Oskar Painter,
Co-Director, Kavli Nanoscience Institute, Caltech, “Both Oxford Instruments
Plasma Technology and the KNI aim to push the state-of-the-art beyond current
capabilities in nanofabrication. The KNI has pursued aggressive acquisition of
strategic instrumentation for advanced nanofabrication capabilities, including
a number of Oxford Instruments systems that are successfully installed and
producing great results for our researchers. Our multi-user laboratories and
cleanrooms for nanostructure synthesis, fabrication, and characterization are
available to users from academia, government and industry.”
Precision
engineered Krystal™ glass bottom plates from Porvair Sciences are manufactured
using a polystyrene upper and a borosilicate glass sheet fixed to the base with
a biocompatible adhesive. This proprietary process results in consistent
flatness (+/- 15 microns) across the base, excellent light transmission and a
flat optical plane for growing cells.
Available in a choice of 24-, 96- and 384-well formats - Krystal glass bottom
plates combine the advantageous optical properties of glass, low background and
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scintillation counting and high-resolution microscopy using confocal imaging.
The complete range of glass bottom microplates is available sterilised for
tissue culture to optimise cell growth or non-sterile for assay development.
The high clarity bottom of each plate in the range offers the advantage of easy
and exact positioning when used in combination with microscopes. Based upon a
standard SBS / ANSI microplate format - Krystal glass bottom plates are fully
compatible with automated liquid handling and robotic devices. All plates are
supplied lidded.
For further information on Krystal glass bottom plates please contact Porvair
Sciences on telephone +44-1372-824290 or email int.sales@porvair-sciences.com.
Publication year:
2012 Source:Journal of Chromatography B, Volume 900 Sun Young Lee,
Na-Hyun Park, Eun-Kyung Jeong, Jae-Woo Wi, Chang-Ju Kim, Jin Young Kim, Moon Kyo
In, Jongki Hong Gas chromatography–mass spectrometry (GC/MS) and liquid
chromatography–mass spectrometry (LC/MS) were compared for their capacity to
metabolite identification, sensitivity, and speed of analysis for propofol and
its metabolites in urine samples. Acidic hydrolysis, liquid–liquid extraction
(LLE), and trimethylsilyl (TMS) derivatization procedures were applied for GC/MS
analysis. The LC/MS analysis used a simple sample pretreatment based on
centrifugation and dilution. Propofol and four metabolites were successfully
analyzed by GC/MS following TMS derivatization. One compound,
di-isopropanolphenol was tentatively characterized as a new metabolite observed
for the first time in human urine. The TMS derivatization greatly improved the
chromatographic properties and detection sensitivity, especially for
hydroxylated metabolites. The lower limits of quantitation (LLOQ) of propofol
were about 325 and 0.51ng/mL for the GC/MS scan mode and selected ion monitoring
(SIM) mode, respectively. In addition, five conjugated propofol metabolites were
successfully analyzed by LC–MS/MS in negative ion mode. The detection
sensitivity for these conjugated metabolites could be greatly enhanced by the
addition of triethylamine to the mobile phase without any loss of LC resolution
capacity. The LLOQs of propofol-glucuronide (PG) were about 1.17 and 2.01ng/mL
for the LC–MS-selected ion monitoring (SIM) and multiple reaction monitoring
(MRM) mode, respectively. Both GC/MS and LC/MS methods sensitively detected nine
metabolites of propofol and could be used to provide complementary data for the
reasonable propofol metabolism study. Urinary excretion profiles for propofol
and its metabolites following administration to human were suggested based on
the total ion chromatograms obtained by GC/MS and LC/MS methods, respectively.
Highlights
► Comprehensive GC/MS and LC/MS methods were
proposed for analysis of propofol and metabolites. ► Both methods provided
excellent sensitivity and selectivity in urine samples. ► 2,6-ω-Di-isopropanol
phenol as new metabolite was first observed in human. ► LLOQ was 0.51ng/mL for
propofol and 2.01ng/mL for propofol-glucuronide.
Publication year:
2012 Source:Journal of Chromatography B, Volume 900 Annika
Lindqvist, Britt Jansson, Margareta Hammarlund-Udenaes A liquid
chromatography–electrospray ionization-tandem mass spectrometry (LC–ESI-MS/MS)
method for the quantification of the opioid peptide DAMGO in rat plasma, as well
as DAMGO and the microdialysis recovery calibrator
[13C2,15N]-DAMGO in microdialysis samples, is described.
The microdialysis samples consisted of 15μL Ringer solution containing 0.5%
bovine serum albumin. Pretreatment of the samples involved protein precipitation
with acetonitrile followed by dilution with 0.01% formic acid. The lower limits
of quantification were 0.52ng/mL and 0.24ng/mL for DAMGO and
[13C2,15N]-DAMGO respectively and the response was linear
up to 5000 fold higher concentrations. The plasma samples (50μL) were
precipitated with acetonitrile containing the isotope labeled analog
[13C2,15N]-DAMGO as internal standard. The method was
linear in the range of 11–110,000ng/mL. The separations were conducted on a
HyPurity C18 column, 50×4.6mm, 3μm particle size, with a mobile phase consisting
of acetonitrile, water and formic acid to the proportions of 17.5:82.5:0.01. Low
energy collision dissociation tandem mass spectrometric (CID-MS/MS) analysis was
carried out in the positive ion mode using multiple reaction monitoring (MRM) of
the following mass transitions: m/z 514.2→453.2 for DAMGO and m/z 517.2→456.2
for [13C2,15N]-DAMGO. The intra-day precision and accuracy
did not exceed 5.2% and 93–104% for both compounds and sample types described.
The inter-day precision an accuracy were <6.8% and 95–105% respectively. The
method described is simple, reproducible and suitable for the analysis of small
sample volumes at low concentrations.
Highlights
► Analysis of DAMGO in microdialysis samples and
plasma using LC–MS/MS is described. ► Plasma method was linear between 11 and
110,000ng/mL. Sample volume was 50μL. ► Microdialysis method was linear between
0.52 and 2600ng/mL. Sample volume was 15μL. ► The intra-day and inter-day
precision and accuracy did not exceed 6.8% and 93–105%. ► The method was applied
to determine the brain distribution of DAMGO in rat.
Publication year:
2012 Source:Journal of Chromatography B, Volume 900 Hongyuan Yan,
Ruiling Wang, Yehong Han, Suting Liu A highly selective molecularly imprinted
solid phase extraction (MISPE) coupled with liquid chromatography–ultraviolet
detection was developed for the determination of salbutamol (SAL) in ham
sausages. New molecularly imprinted polymers (MIPs) were synthesized with
phenylephrine as dummy template and it revealed good affinity to SAL in
methanol–acetonitrile system. Adsorption capacity of the MIPs was evaluated by
dynamic adsorption experiments. The MIPs were used as SPE sorbent for the
selective clean-up and pre-concentration of SAL in ham sausage samples. The
results showed that the matrix compounds presented in ham sausage samples could
be removed effectively and the recoveries of SAL at three spiked levels were
ranged from 82.6 to 100.5% with the relative standard deviation (RSD) of less
than 3.6%. This method is simple and sensitive, and is therefore an alternative
tool to the existing methods for analyzing residual SAL in biological samples.
Highlights
► A simple and rapid MISPE–HPLC method for
determination of salbutamol in ham sausages. ► The new MIPs were obtained by
phenylephrine as dummy template in methanol–acetonitrile solution. ► Rapid
screening of salbutamol in ham sausages, while interferences from milk matrix
were eliminated. ► Extraction efficiency was markedly increased with reduced
equilibrium time. ► This method improved the selectivity and eliminated the
effect of template leakage on quantitative analysis.
Publication year:
2012 Source:Journal of Chromatography B, Volume 900 Akina Muto,
Hajime Takei, Atsushi Unno, Tsuyoshi Murai, Takao Kurosawa, Shoujiro Ogawa,
Takashi Iida, Shigeo Ikegawa, Jun Mori, Akira Ohtake, Takayuki Hoshina, Tatsuki
Mizuochi, Akihiko Kimura, Alan F. Hofmann, Lee R. Hagey, Hiroshi Nittono The
synthesis of bile salts from cholesterol is a complex biochemical pathway
involving at least 16 enzymes. Most inborn errors of bile acid biosynthesis
result in excessive formation of intermediates and/or their metabolites that
accumulate in blood and are excreted in part in urine. Early detection is
important as oral therapy with bile acids results in improvement. In the past,
these intermediates in bile acid biosynthesis have been detected in neonatal
blood or urine by screening with FAB-MS followed by detailed characterization
using GC–MS. Both methods have proved difficult to automate, and currently most
laboratories screen candidate samples using LC–MS/MS. Here, we describe a new,
simple and sensitive analytical method for the identification and
characterization of 39 conjugated and unconjugated bile acids, including
Δ4-3-oxo- and Δ4,6-3-oxo-bile acids (markers for
Δ4-3-oxo-steroid 5β-reductase deficiency), using liquid
chromatography-electrospray ionization tandem mass spectrometry (LC–ESI-MS/MS).
In this procedure a concentrated, desalted urinary sample (diluted with ethanol)
is injected directly into the LC–ESI-MS/MS, operated with ESI and in the
negative ion mode; quantification is obtained by selected reaction monitoring
(SRM). To evaluate the performance of our new method, we compared it to a
validated method using GC–MS, in the analysis of urine from two patients with
genetically confirmed Δ4-3-oxo-steroid 5β-reductase deficiency as
well as a third patient with an elevated concentration of abnormal conjugated
and unconjugated Δ4-3-oxo-bile acids. The Δ4-3-oxo-bile
acids concentration recovered in three patients with 5β-reductase deficiency
were 48.8, 58.9, and 49.4μmol/mmol creatinine, respectively by LC–ESI-MS/MS.
Highlights
► We analyze 39 bile acids including abnormal bile
acids by LC–ESI-MS/MS. ► We analyze urine from patients with 5β-reductase
deficiency by LC–ESI-MS/MS. ► The urine from those patients elevated
concentration of Δ4-3-oxo-bile acids. ► The results obtained with
LC–ESI-MS/MS agree quite well with those obtained by GC–MS.
Publication year:
2012 Source:Journal of Chromatography B, Volume 900 Valeria Boeris,
Izabella Balce, Rami Reddy Vennapusa, Miguel Arévalo Rodríguez, Guillermo Picó,
Marcelo Fernández Lahore β-Galactosidase is a hydrolase enzyme that catalyzes
the hydrolysis of β-galactosides into monosaccharides; its major application in
the food industry is to reduce the content of lactose in lactic products. The
aim of this work is to recover this enzyme from a cell lysate by adsorption onto
Streamline-DEAE in an expanded bed, avoiding, as much as possible, biomass
deposition onto the adsorbent matrix. So as to achieve less cell debris–matrix
interaction, the adsorbent surface was covered with polyvinyl pyrrolidone. The
enzyme showed to bind in the same extent to naked and covered Streamline-DEAE
(65mg β-gal/g matrix) in batch mode in the absence of any biomass. The kinetics
of the adsorption process was studied and no effect of the polyvinyl pyrrolidone
covering was found. The optimal conditions for the recovery were achieved by
using a lysate made of 40% wet weight of cells, a polyvinyl pyrrolidone-covered
matrix/lysate ratio of 10% and carrying out the adsorption process in expanded
bed with recirculation over 2h in 20mM phosphate buffer pH 7.4. The fraction
recovered after the elution contained 65% of the initial amount of enzyme with a
12.6-fold increased specific activity with respect to the lysate. The polyvinyl
pyrrolidone content in the eluate was determined and found negligible. The
remarkable point of this work is that it was possible to partially purify the
enzyme using a feedstock containing an unusually high biomass concentration in
the presence of polyvinyl pyrrolidone onto weak anion exchangers.
Highlights
► β-Galactosidase production from recombinant
Saccharomyces cerevisiae. ► Cell lysate and adsorption onto Streamline-DEAE in
an expanded bed. ► Adsorption of target proteins from unclarified feedstock. ►
Cell debris–matrix interaction, and the effect of polyvinyl pyrrolidone on the
enzyme adsorption.
Publication year:
2012 Source:Journal of Chromatography B, Volume 900 Mariska Davids,
Eliane Swieringa, Fredrik Palm, Desirée E.C. Smith, Yvo M. Smulders, Peter G.
Scheffer, Henk J. Blom, Tom Teerlink Production of the endogenous vasodilator
nitric oxide (NO) from l-arginine by NO synthase is modulated by l-homoarginine,
l-monomethylargine (MMA), asymmetric dimethylarginine (ADMA) and symmetric
dimethylarginine (SDMA). Here we report on a stable isotope dilution liquid
chromatography tandem mass spectrometry (LC–MS/MS) method for simultaneous
determination of these metabolites in plasma, cells and tissues. After addition
of the internal standards (D7-ADMA, D4-l-homoarginine and
13C6-l-arginine), analytes were extracted from the samples using
Waters Oasis MCX solid phase extraction cartridges. Butylated analytes were
separated isocratically on a Waters XTerra MS C18 column (3.5μm, 3.9mm×100mm)
using 600mg/L ammonium formate in water - acetonitrile (95.5:4.5, v/v)
containing 0.1vol% formic acid, and subsequently measured on an AB Sciex API
3000 triple quadrupole mass spectrometer. Multiple reaction monitoring in
positive mode was used for analyte quantification. Validation was performed in
plasma. Calibration lines were linear (r 2 ≥0.9979) and lower limits
of quantification in plasma were 0.4nM for ADMA and SDMA and 0.8nM for the other
analytes. Accuracy (% bias) was <3% except for MMA (<7%), intra-assay
precision (expressed as CV) was <3.5%, inter-assay precision <9.6%, and
recovery 92.9–103.2% for all analytes. The method showed good correlation (r
2 ≥0.9125) with our previously validated HPLC-fluorescence method for
measurement in plasma, and was implemented with good performance for measurement
of tissue samples. Application of the method revealed the remarkably fast (i.e.
within 60min) appearance in plasma of stable isotope-labeled ADMA, SDMA, and MMA
during infusion of D3-methyl-1-13C-methionine in healthy volunteers.
Highlights
► The endogenous vasodilator nitric oxide (NO) is
produced from arginine by NO synthase. ► Homoarginine and the methylated
arginines MMA, ADMA, and SDMA modulate NO production. ► An LC–MS/MS method for
the simultaneous measurement of these compounds was developed. ► Stable isotope
labeled arginine, homoarginine and ADMA served as internal standards. ► The
method was validated for plasma and is also suitable for analysis of tissue
samples.
Publication year:
2012 Source:Journal of Chromatography B, Volume 900 Charlotte
Desoubries, Florence Chapuis-Hugon, Anne Bossée, Valérie Pichon Degradation
products of chemical warfare agents are considered as important environmental
and biological markers of chemical attacks. Alkyl methylphosphonic acids
(AMPAs), resulting from the fast hydrolysis of nerve agents, such as sarin and
soman, and the methylphosphonic acid (MPA), final degradation product of AMPAs,
were determined from complex matrices by using an emergent and miniaturized
extraction technique, the hollow fiber liquid-phase microextraction (HF-LPME),
before their analysis by liquid chromatography coupled to mass spectrometry
(LC–MS). After studying different conditions of separation in the reversed phase
LC–MS analysis, the sample treatment method was set up. The three-phase HF-LPME
was carried out by using a porous polypropylene (PP) hollow fiber impregnated
with 1-octanol that separates the donor and acceptor aqueous media. Various
extraction parameters were evaluated such as the volume of the sample, the
effect of the pH and the salt addition to the sample, the pH of the acceptor
phase, the extraction temperature, the stirring speed of the sample, the
immersion time in the organic solvent and the time of extraction. The optimum
conditions were applied to the determination of MPA and five AMPAs in real
samples, such as surface waters and urine. Compounds were extracted from a 3mL
acidified sample into only 6μL of alkaline water without any other pretreatment
of the complex matrices. Enrichment factors (EFs) higher than 170 were obtained
for three less polar AMPAs. Limits of quantification (LOQs) in the
0.013–5.3ngmL−1 range were obtained after microextraction of AMPAs
from river water and in the range of 0.056–4.8ngmL−1 from urine
samples with RSD values between 1 and 9%.
Highlights
► High potential of HF-LPME applied to reduced size
samples. ► High enrichment factor for the extraction of polar compounds from
water and urine. ► Quantitative extraction of AMPAs from surface waters and
urine samples. ► High sensitivity for the LC/MS analysis of AMPAs without any
derivatization step.
Publication year:
2012 Source:Journal of Chromatography B, Volume 900 Hui Li, Xi Xia,
Yanan Xue, Shusheng Tang, Xilong Xiao, Jiancheng Li, Jianzhong Shen A rapid
and sensitive ultra-high performance liquid chromatography tandem mass
spectrometric method was developed for simultaneous quantification of
amoxicillin and prednisolone in bovine milk. In this method, amoxicillin,
prednisolone and the internal standards penicillin G-d7 (for amoxicillin) and
prednisolone-d6 were extracted from bovine milk using acetonitrile. The C18
solid phase extraction cartridges were selected for cleaning-up the extracts.
The analytes were determined using a triple quadrupole mass spectrometry in
positive electrospray ionization and multiple reaction monitoring mode.
Calibration curves were linear over a concentration range of 2–1000μg/kg for the
analytes. The mean recoveries were 89.2–92.3% for amoxicillin and 98.7–102.3%
for prednisolone. Limits of detection were 0.5μg/kg for the analytes, and the
limits of quantitation were 2μg/kg. Decision limit (CCα) and detection
capability (CCβ) have also been estimated for each analyte. The method was
validated according to the Commission Decision 2002/657/EC and successfully
applied to the analysis of amoxicillin and prednisolone in real samples.
Highlights
► Amoxicillin and prednisolone were determined
simultaneously using UPLC–MS/MS. ► Deuterated internal standards were applied to
accurate quantification. ► LODs for two analytes were far below MRLs set by EU
in developed method. ► Recoveries in raw milk were good with a simple sample
preparation.
Publication year:
2012 Source:Journal of Chromatography B, Volume 900 Christelle
Simon-Colin, Christelle Gouin, Pierre Lemechko, Nelly Kervarec, Jean
Guezennec A new gas chromatography–mass spectrometry (GC–MS) method for the
localization of double bond in monounsaturated 3-hydroxyalkenoic acids monomers
has been developed. A three steps derivation assay was used including a
methanolysis, then acetylation and dimethyldisulfide (DMDS) addition to alkene
groups. Electron impact GC–MS analysis of such derivatives offers characteristic
fragments allowing the unambiguous determination of double bond position in side
chain. This novel method is well-suited for the routine analysis of
poly-beta-hydroxyalkanoates (PHAs), and was used to characterize monounsaturated
monomers in both 3-hydroxyalkenoic acids standards as well as in mcl-PHAs and
poly(3-hydroxyoctanoate-co-3-hydroxyundecenoate) (PHOU) produced by bacterial
strain Pseudomonas guezennei from glucose or a mixture of sodium octanoate plus
10-undecenoic acid, respectively.
Highlights
► Localization of double bond in monounsaturated
3-hydroxyalkenoic acids by GC–MS. ► The new method implies methanolysis, then
acetylation and thiomethylation. ► The method was successfully applied to
bacterial poly-beta-hydroxyalcanoates.
Publication year:
2012 Source:Journal of Chromatography B, Volume 900 Valerie Orr,
Jeno Scharer, Murray Moo-Young, C. Howie Honeyman, Drew Fenner, Lisa Crossley,
Shing-Yi Suen, C. Perry Chou Downstream purification often represents the
most cost-intensive step in the manufacturing of recombinant proteins since
conventional purification processes are lengthy, technically complicated, and
time-consuming. To address this issue, herein we demonstrated the simultaneous
clarification and purification of the extracellularly produced recombinant
protein by Escherichia coli using an integrated system of tangential flow
filtration and anion exchange membrane chromatography (TFF-AEMC). After
cultivation in a bench-top bioreactor with 1L working volume using the developed
host/vector system for high-level expression and effective secretion of
recombinant penicillin G acylase (PAC), the whole culture broth was applied
directly to the established system. One-step purification of recombinant PAC was
achieved based on the dual nature of membrane chromatography (i.e.
microfiltration-sized pores and anion-exchange chemistry) and cross-flow
operations. Most contaminant proteins in the extracellular medium were captured
by the anion-exchange membrane and cells remained in the retentate, whereas
extracellular PAC was purified and collected in the filtrate. The batch time for
both cultivation and purification was less than 24h and recombinant PAC with
high purity (19U/mg), yield (72% recovery), and productivity (41mg of purified
PAC per liter of culture) was obtained. Due to the nature of the non-selective
protein secretion system and the versatility of ion-exchange membrane
chromatography, the developed system can be widely applied for effective
production and purification of recombinant proteins.
Highlights
► A novel protein separation system of TFF-AEMC was
developed. ► The system was applied for effective culture clarification and
protein purification. ► The batch time for combined cultivation and purification
was less than 24h. ► Recombinant protein with a high purity and yield was
obtained.
Publication year:
2012 Source:Journal of Chromatography B, Volume 900 Walburga
Hanekamp, Matthias Lehr An on-line solid-phase extraction (SPE)–liquid
chromatographic method with ultraviolet detection at 200nm for screening of
inhibitors of cytosolic phospholipase A2α (cPLA2α) was developed and validated.
cPLA2α was isolated from porcine platelets. Enzyme activity was determined by
measuring the release of arachidonic acid from a phospholipid substrate using
automated on-line sample clean up on a trap column followed by isocratic
back-flush elution on a RP18 analytical column. While the use of a conventional
RP18 column for trapping the analyte led to peak broadening only after a few
runs due to pollution of the column by binding of components present in the
enzyme preparation, the application of a turbulent flow column (TurboFlow
Cyclone™) resulted in sharp peaks even after a plurality of injections.
Interestingly, for sample introduction a turbulent flow of the mobile phase
produced by high flow rates was not necessary to maintain good peak shapes. The
same result could also be achieved applying low flow rates (0.5mL/min). Several
known cPLA2α inhibitors were used to validate the test system.
Highlights
► Automated on-line solid-phase extraction–HPLC/UV
method for cPLA2α inhibitor screening. ► Application of a turbulent flow column
for trapping of the enzyme product arachidonic acid. ► A turbulent flow of the
mobile phase is not necessary for effective separation of
proteins.
Publication year:
2012 Source:Journal of Chromatography B, Volume 900 Mohammad Reza
Hadjmohammadi, Mona Soltani, Vahid sharifi The applicability of hollow fiber
liquid phase microextraction (HF-LPME) was evaluated for extraction and
preconcentration of apigenin prior to its determination by HPLC. Different
parameters affecting the HF-LPME recovery such as nature of organic solvent, pH
of donor and acceptor phases, extraction time, stirring speed, salt addition
were optimized. Under optimum conditions (1-octanol as organic solvent, pH of
the donor phase=3 and pH of acceptor phase=11.5, extraction time of 75min,
stirring speed of 1000rpm) limit of detection (LOD) of 0.1ng/mL, linear range of
0.5–300ng/mL and correlation of determination (R 2) of 0.9956 were
obtained. The relative intra and inter-day standard deviations (RSD%) based on
five replicate measurement were 3.5% and 10.7% respectively. Enrichment factor
of 315 and recovery 85% were achieved. Finally, the applicability of the
proposed method was evaluated by extraction and determination of apigenin in
urine sample after consumption of Satureja sahendica Bornm. which is a native
medicinal plant from Iran. Concentration of apigenin in urine sample was found
to be 6.20ng/mL.
Highlights
► A simple and sensitive method for determination
of apigenin has been introduced. ► Hollow fiber liquid phase microextraction was
used for extraction of apigenin. ► Trace amount of apigenin in biological sample
was preconcentrated using this method. ► The HF-LPME method has excellent
clean-up and high-preconcentration factor.
Publication year:
2012 Source:Journal of Chromatography B, Volume 900 Wei Chen, Patty
Fan-Havard, Lisa D. Yee, Yu Cao, Gary D. Stoner, Kenneth K. Chan, Zhongfa
Liu Curcumin is a widely used herbal medicine for various human diseases
including inflammation and cancer. The demonstration and optimization of
curcumin's activities in the clinical setting, however, have been compromised by
its poor bioavailability and the lack of analytic methods to monitor its
absorption. In this paper, we report the first validated liquid
chromatography–tandem mass spectrometric method for simultaneous quantification
of curcumin and its major metabolite: curcumin-O-glucuronide (COG), in the
linear range of 2.0–2000ng/mL in human plasma. The intra-day and inter-day
accuracies of curcumin and COG in human plasma were in the range of 91.3–111.5%
and 82.7–109.2% and their co-efficiency of variations were in the range of
3.5–12.7% and 3.1–11.3%, respectively. This method was capable of detecting only
COG in human plasma samples from two healthy volunteers after an oral ingestion
of curcumin.
Highlights
► First direct method to measure
curcumin-O-glucuronide (COG) in human plasma. ► The LLOQ is 2ng/mL with CVs
(<15%) and accuracy (85–115%). ► Capable of characterizing the
pharmacokinetics of COG up to 24h in human.
Publication year:
2012 Source:Journal of Chromatography B, Volume 900 Ming-Xia Zhang,
Cun Li, Yin-Liang Wu A simple, sensitive and reliable analytical method was
developed for the determination of a new beta-agonist phenylethanolamine A in
animal hair, tissues and animal feeds by ultra high performance liquid
chromatography–positive electrospray ionization tandem mass spectrometry
(UHPLC–ESI-MS/MS) with QuEChERS. Samples were extracted with acetonitrile/water
(80:20, v/v). The extract was purified through QuEChERS method, then was dried
with nitrogen and residues were redissolved in mobile phase for hair sample or
directly diluted with 0.1% formic acid in water for other samples, and analyzed
by LC–MS/MS on a Waters Acquity BEH C18 column with 0.1% formic acid in
water/methanol as mobile phase with gradient elution. The samples were
quantified using phenylethanolamine A-D3 as internal standards. The proposed
method was validated according to the European Commission Decision 2002/657/EC
determining specificity, decision limit (CCα), detection capability (CCβ),
recovery, precision, linearity, robustness and stability. The CCα values ranged
from 0.10 to 0.26μg/kg. The CCβ values ranged from 0.20 to 0.37μg/kg. The mean
recoveries of 95.4–108.9% with intra-day CVs of 2.2–5.6% and inter-day CVs of
3.1–6.2% were obtained. The method is demonstrated to be suitable for the
determination of phenylethanolamine A in animal hair, tissues and animal feeds.
The total time required for the analysis of one sample except animal hair
sample, including sample preparation, was about 25min.
Highlights
► A LC–MS–MS method has been developed to determine
phenylethanolamine A residues. ► A simple pretreatment method based on QuEChERS
has been developed. ► Animal hair, tissues and feeds were successfully analyzed
using the method. ► The method was fast, reliable, convenient and sensitive.
