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
Monday 11 February 2013
Just Published: Journal of Chromatography B
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:
1 March 2013 Publication year:
2013 Source:Journal of Chromatography B, Volumes
919–920
High-performance liquid chromatography–tandem mass spectrometry
(LC–MS/MS) is a standard analytical technique for therapeutic drug monitoring
(TDM). A rapid LC–MS/MS method was developed for simultaneous quantitation of 3
antifungals and one active metabolite (posaconazole, voriconazole, itraconazole,
and hydroxy-itraconazole), 5 antibiotics (daptomycin, ciprofloxacin, oxacillin,
levofloxacin, and rifampicin), an antineoplastic agent (imatinib), and an
antiretroviral (raltegravir) in human plasma. Protein precipitation of 10μL of
plasma with acetonitrile was used as a single-extraction procedure. After
2-dimensional LC, all drugs were quantified by electrospray ionization-triple
quadrupole mass spectrometry by selected reaction monitoring detection in the
positive mode. The method was validated per FDA recommendations including the
study of extraction recovery (from 79.3% to 105.9%) and matrix effect via ion
suppression/enhancement phenomenon. This method is precise (intra- and
inter-assay coefficients of variation of 1.95–12.77%, 2.56–8.16% and 2.12–11.38%
for low, medium and high levels of internal quality controls respectively) and
accurate (intra- and inter-assay biases of 0.19–12.67%, 0.04 to −12.17% and
0.22–12.98% respectively). This method is an efficient tool for routine TDM and
optimization of laboratory resource utilization.
Highlights
► Fast and simultaneous quantitation of different
classes of drugs in human plasma. ► Simple sample preparation step by protein
precipitation. ► LC–MS/MS analysis with online sample clean up. ► Efficient tool
for optimization of laboratory resource utilization.
1 March 2013 Publication year:
2013 Source:Journal of Chromatography B, Volumes 919–920
The
cytotoxic agent Gemcitabine (2′,2′-difluoro-2′-deoxycytidine) has been proved to
be effective in the treatment of malignant gliomas. A rapid, sensitive and
specific ultra performance liquid chromatography with tandem mass spectrometry
(UPLC–MS/MS) assay using microdialysis sampling was developed and validated to
quantify gemcitabine and its major metabolite 2′,2′-difluoro-2′-deoxyuridine
(dFdU) in Sprague–Dawley rat bearing 9L glioma. Microdialysis probes were
surgically implanted into the area of rat brain tumor in the striatal
hemisphere, and artificial cerebrospinal fluid was used as a perfusion medium.
The samples were analyzed directly by UPLC–MS/MS after the addition of
5-bromouracil as an internal standard (IS). Separation was achieved on Agilent
SB-C18 (50mm×2.1mm I.D., 1.8μm) column at 40°C using an isocratic elution method
with acetonitrile and 0.1% formic acid (4:96, v/v) at a flow rate of 0.2mL/min.
Detection was performed using electrospray ionization in positive ion selected
reaction monitoring mode by monitoring the following ion transitions m/z
264.0→112.0 (gemcitabine), m/z 265.1→113.0 (dFdU) and m/z 190.9→173.8 (IS). The
calibration curves of gemcitabine and dFdU were linear in the concentration
range of 0.66–677.08ng/mL and 0.31–312.00ng/mL, respectively. The lower limit of
quantification of gemcitabine and dFdU were 0.66ng/mL and 0.31ng/mL,
respectively. The lower limit of detection of gemcitabine and dFdU were
calculated to be 0.2ng/mL and 0.1ng/mL, respectively. All the validation data,
such as intra- and inter-day precision, accuracy, selectivity and stability,
were within the required limits. The validated method was simple, precise and
accurate, which was successfully employed to determinate the concentrations of
gemcitabine and dFdU in the extracellular fluid of rat brain tumor.
Highlights
► Gemcitabine is effective in the treatment of
malignant gliomas. ► Gemcitabine's metabolite dFdU may contribute to
gemcitabine's toxicity. ► A microdialysis technique with UPLC–MS/MS method was
developed. ► All the validation data are within the required limits. ► The
method was applied to determine gemcitabine and dFdU in rat
tumor.
15 February 2013 Publication year:
2013 Source:Journal of Chromatography B, Volumes
917–918
Clopidogrel has been applied in antiplatelet therapy since 1998
and is the thienopyridine with the largest clinical experience. By 2011,
clopidogrel (Plavix®) was the second top-selling drug in the world.
Following complete patent expiry in 2012/2013 its use is expected to grow even
further from generics entering the market. Prefaced by a brief description of
clopidogrel metabolism, this review analyzes analytical methods addressing the
quantification of clopidogrel and its metabolites in biological samples.
Techniques that have been applied to analyze human plasma or serum are
predominantly LC–MS and LC–MS/MS. The lowest level of clopidogrel quantification
that has been achieved is 5pg/mL, the shortest runtime is 1.5min and almost 100%
recovery has been reported using solid-phase extraction for sample preparation.
Graphical abstract
Highlights
► Overview of analytical
techniques for the quantification of clopidogrel and clopidogrel carboxylic acid
in biological samples. ► New developments addressing the determination of the
active clopidogrel metabolite. ► Thorough comparison of validation data obtained
by the reviewed literature reports.
15 February 2013 Publication year:
2013 Source:Journal of Chromatography B, Volumes
917–918
Ultrasound-assisted emulsification microextraction (USAE-ME)
procedure coupled with UV–vis spectrophotometric measurement has been developed
for determination of thiocyanate ion (SCN−) in water and biological
fluids samples. The method is based on protonation of SCN− ions in
acidic medium and extraction of thiocyanic acid into fine droplets of chloroform
as an extraction solvent contains rhodamine B (RhB). The RhB was protonated in
presence of thiocynanic acid to form highly colored ion-pair complex of
[thiocynate][RhBH+] in chloroform, which used for subsequent
spectrophotometric determination of SCN− ions. Experimental
parameters for both spectrophotometric reaction and USAE-ME procedure have been
optimized. Under optimized conditions the calibration curve for SCN−
showed good linearity in the range of 38.0–870.0ngmL−1 (R
2 =0.9967). The limit of detection (S/N=3) and preconcentration
factor were 5.0ngmL−1 and 40, respectively. Relative standard
deviation for determination of 200ngmL−1 of SCN− was 2.8%
(n =5). The proposed method has been successfully applied for determination of
SCN− ion in tap water, mineral bottled water and human saliva and
urine samples with an average recovery of 99.2%.
Highlights
► For first time, USAE-ME coupled with UV–vis
spectrophotometry for determination of an inorganic spicies (thiocyanate ion). ►
The method was developed for analysis of drinking mineral water, urine and
saliva samples. ► High enrichment factor and ease of operation are the main
advantages of proposed method. ► Hyphenation of USAE-ME with ordinary UV–vis
spectrophotometry improved the sensitivity significantly.
15 February 2013 Publication year:
2013 Source:Journal of Chromatography B, Volumes 917–918
A
simple and especially rapid method, pressurized liquid extraction, has been
developed and applied to the quantitative determination of oxytetracycline,
tetracycline, chlortetracycline, minocycline, methacycline, demeclocycline and
doxycycline in egg, fish and shrimp. The procedure consisted of a trichloracetic
acid/methanol extraction conducted at elevated temperature (60°C) and pressure
(65bar), without further clean-up, the extraction solution was concentrated and
finally for high-performance liquid chromatography analysis. The limits of
detection were 5.0–10.0μg/kg and the limits of quantification were
10.0–15.0μg/kg for tetracyclines in egg, fish and shrimp using UV detection. The
analytical limits CCα and CCβ were also calculated. The recoveries of
tetracyclines spiked at levels of 15–300μg/kg, averaged 75.6–103.5% with the
relative standard deviation values less than 11%. The optimized procedure has
been successfully applied to real samples in our laboratories. It demonstrated
that the new method was robust and useful for monitoring and quantification of 7
tetracycline residues in food of animal origin.
Highlights
► Pressurized liquid extraction has been developed
to the HPLC quantitative determination of seven tetracyclines in egg, fish and
shrimp. ► The extraction procedure is simple and rapid. ► The optimized
procedure has been successfully applied to real samples. ► The method is robust
and useful for monitoring and quantification of tetracycline
residues.
15 February 2013 Publication year:
2013 Source:Journal of Chromatography B, Volumes 917–918
A
sensitive, selective, and quantitative method for the determination of urea has
been developed and validated in human epithelial lining fluid (ELF; the
supernatant from bronchoalveolar lavage). The method employs a simple
derivatization of urea with camphanic chloride to improve the chromatographic
retention and separation. The derivatization was performed after drying an
aliquot of ELF (20μL) without prior sample clean-up. Ultra High Performance
Liquid Chromatography (UHPLC) on a HSS-T3 stationary phase column with 1.8μm
particle size was used for chromatographic separation coupled to tandem mass
spectrometry. The method was validated over the concentration range of
8.78–103.78μg/mL, however the dynamic range can be further lowered if needed.
The results from assay validation show that the method is rugged, precise,
accurate, and well-suited to support analysis of urea in ELF samples. In
addition, the relatively small sample volume (20μL) and a run time of 1.5min
facilitate automation and allow for high-throughput analysis. This
derivatization method was compared to a commercially available colorimetric
assay kit, and it was used in a preclinical non-GLP mouse study where urea
measurements were used as marker of bronchoalveolar lavage fluid dilution.
Highlights
► Derivatization with improved chromatographic
retention and separation. ► The derivatization was performed without prior
sample clean-up. ► The method was validated over the concentration range of
8.78–103.78μg/mL. ► This method was compared to a commercially available
colorimetric assay kit. ► The method can also be adapted for determination of
urea in plasma samples.
15 February 2013 Publication year:
2013 Source:Journal of Chromatography B, Volumes 917–918
A
basic polypeptide L2 (252–273) derived from Escherichia coli ribosomal protein
L2 was used as a purification tag. In order to develop faster, less expensive
methods for expression and purification of proteins, the L2 (252–273)-small
ubiquitin like modifier (SUMO) fusion expression system was constructed. We
comparatively analyzed the adsorption properties of the deleted protein of L2
(L2 (252–273)) on diatomite and superparamagnetic carboxymethyl chitosan
nanoparticles. The time required to reach adsorption equilibrium of L2 (252–273)
fusion protein on diatomite was shorter than that of L2 (252–273) fusion protein
on magnetic particles. The maximum adsorption capacity of L2 (252–273) fusion
protein on magnetic particles was about 5 times larger than that of L2 (252–273)
fusion protein on diatomite. SUMO was introduced as a specific protease cleavage
site between the target protein and the purification tags. The enhanced green
fluorescent protein (EGFP) as a model protein was fused with the L2
(252–273)-SUMO fusion protein and purified by a simple method which involves the
electrostatic adsorption of L2 (252–273) fusion proteins on superparamagnetic
carboxymethyl chitosan nanoparticles and the L2 (252–273)-SUMO fusion partner
was removed based on the robust cleavage by the poly lysine tagged SUMO
protease. The high purity of tag-free EGFP (>93%) was obtained. Our results
preliminary proved that the system was an effective fusion expression system for
the production of recombinant proteins in E. coli.
Highlights
► The L2 (252–273) from E. coli ribosomal protein L2
was used as a purification tag. ► Magnetic nanoparticles had a higher adsorption
loading than the other adsorbents. ► Tag-free target protein purification by L2
(252–273)-SUMO fusion technology. ► The tag-free recombinant EGFP with a purity
of greater than 93% was obtained.
15 February 2013 Publication year:
2013 Source:Journal of Chromatography B, Volumes 917–918
A
simple liquid chromatography/ion trap mass spectrometry method for the
quantification of amlodipine and atorvastatin with its metabolites, ortho and
para hydroxy atorvastatin, simultaneously in human plasma was developed.
Analytes with internal standard were extracted by protein direct precipitation
with acetonitrile. Adequate chromatographic separation was achieved using
Phenomenex Synergi 4u polar-RP 80A (150mm×4.6mm, 4μm) column in the isocratic
elution mode and the eluent was water/methanol (14:86%, v/v) adjusted by
trichloroacetic acid to pH 3.2 which was delivered isocratically at constant
flow rate of 0.50mL/min. Standard solutions for the analytes were prepared using
amlodipine besylate, atorvastatin calcium, ortho-hydroxy atorvastatin dihydrate
monosodium salt, para-hydroxy atorvastatin disodium salt, and pravastatin sodium
as an internal standard. The method validation intends to investigate
specificity, sensitivity, linearity, precision, accuracy, recovery, matrix
effect and stability according to USFDA guideline. Standard calibration levels
were prepared by pooled human plasma to attain final dynamic range of
0.2–20.0ng/mL for amlodipine, 1.5–150ng/mL for atorvastatin, 1.0–100.0ng/mL for
ortho-hydroxy atorvastatin and 0.2–20.0ng/mL for para-hydroxy atorvastatin.
Clinical bioequivalence study was successfully investigated by the application
of this validated bioanalytical method in order to evaluate bioequivalence of
two commercial products 10mg amlodipine/80mg atorvastatin in a single dose. In
this study, 29 healthy volunteers were participated in randomized, two periods,
double blend, open label cross over design. Pharmacokinetic parameters of C max,
AUC0–t and AUC0–∞ were calculated to compare a test product with
CADUET® reference product.
Highlights
► LC/MS-method for analysis of amlodipine and
atorvaststin in plasma has been developed. ► Method of protein direct
precipitation with acetonitrile was used for extraction. ► Method was validated
through investigation of seven parameters. ► CADUET (Pfizer), new combination of
the two drugs was analyzed for the first time. ► The method was successfully
applied in a clinical bioequivalence study.
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