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World Congress on Biosensors 2014
Biosensors 2014
Monday, 4 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:
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.
15 February 2013 Publication year:
2013 Source:Journal of Chromatography B, Volumes 917–918
The
formation of drug–protein adducts following the bioactivation of drugs to
reactive metabolites has been linked to adverse drug reactions (ADRs) and is a
major complication in drug discovery and development. Identification and
quantification of drug–protein adducts in vivo may lead to a better
understanding of drug toxicity, but is challenging due to their low abundance in
the complex biological samples. Human serum albumin (HSA) is a well-known target
of reactive drug metabolites due to the free cysteine on position 34 and is
often the first target to be investigated in covalent drug binding studies.
Presented here is an optimized strategy for targeted analysis of low-level
drug–albumin adducts in serum. This strategy is based on selective extraction of
albumin from serum through affinity chromatography, efficient sample treatment
and clean-up using gel filtration chromatography followed by tryptic digestion
and LC–MS analysis. Quantification of the level of albumin modification was
performed through a comparison of non-modified and drug-modified protein based
on the relative peak area of the tryptic peptide containing the free cysteine
residue. The analysis strategy was applied to serum samples resulting from a
drug exposure experiment in mice, which was designed to study the effects of
different acetaminophen (APAP) treatments on drug toxicity. APAP is bioactivated
to N-acetyl-p-benzoquinoneimine (NAPQI) in both humans and mice and is known to
bind to cysteine 34 (cys34) of HSA. Analysis of the mouse serum samples revealed
the presence of extremely low-level NAPQI-albumin adducts of approximately 0.2%
of the total mouse serum albumin (MSA), regardless of the length of drug
exposure. Due to the targeted nature of the strategy, the NAPQI-adduct formation
on cys34 could be confirmed while adducts to the second free cysteine on
position 579 of MSA were not detected.
Highlights
► A generic strategy was developed for the analysis
of drug–albumin adducts in serum. ► Identification and localization of
low-abundant NAPQI-albumin adducts in mouse serum. ► Quantification of low
levels of drug–protein adduct formation in vivo.
15 February 2013 Publication year:
2013 Source:Journal of Chromatography B, Volumes
917–918
Ureidomustin hydrochloride (BO-1055) was designed as a
water-soluble nitrogen-mustard, which exhibited potent anticancer activity and
was selected as a candidate for preclinical studies. However, up to date, there
is rarely an easy and economic method to quantize ureidomustin in the biological
samples. The aim of this study is to develop a simple yet valid quantization
method to tackle this challenge. Here we present a combined high-performance
liquid chromatography with photodiode array (HPLC-PDA) method in quantizing the
ureidomustin in the plasma and various organs of Sprague-Dawley rats. The method
was validated in terms of precision, accuracy, and extraction recovery.
Furthermore, the established method was applied to study pharmacokinetics of
ureidomustin in the rat's plasma and verified via a liquid chromatography tandem
mass spectrometry (LC–MS/MS) method. Calibration curves of the plasma and organ
samples were falling at the range between 0.5–50μg/mL and 0.1–50μg/mL (r
2 ≥0.999 and CV≤±15%), respectively. The limits of detection (LOD)
were 0.1μg/mL for plasma samples and 0.05μg/mL for organ samples, while the
detection limits of quantification (LOQ) were 0.5μg/mL for plasma samples and
0.1μg/mL for organ samples. The average recovery of ureidomustin was about 83%.
These results demonstrated a linear pharmacokinetic pattern at dosages of 10 and
30mg/kg. The pharmacokinetic data revealed that ureidomustin was best fitted to
a two-compartment model with a rapid distribution phase and a slow elimination
phase. Besides, after a short intravenous administration time at the dose of
10mg/kg, ureidomustin was found to be quickly distributed to all organs in rats,
accumulated mainly in the kidney, and only a limited amount was detected in the
brain.
Highlights
► Ureidomustin hydrochloride (BO-1055) was designed
as a water-soluble nitrogen-mustard. ► An HPLC with photodiode array was used to
perform the preclinical pharmacokinetics of ureidomustin. ► Ureidomustin
appeared to be a two-compartment model in the rats. ► The results demonstrate a
rapid distribution and a slow elimination after ureidomustin
administration.
15 February 2013 Publication year:
2013 Source:Journal of Chromatography B, Volumes 917–918
A
procedure involving acetonitrile-based extraction combined with dispersive
liquid–liquid microextraction (DLLME) and detection by ultra high performance
liquid chromatography–tandem mass spectrometry (UHPLC–MS/MS) was used for
determination of 39 pesticides in ginseng. The extraction of pesticide residues
in ginseng was performed with acetonitrile, applying QuEChERS methodology, and
the extract was further disposed by DLLME method before analyzed by UHPLC–MS/MS.
The average recoveries ranged from 70 to 120% for 82% of the analytes with RSD
lower than 15%. The calibration curves obtained with blank matrices were linear
with a correlation coefficient of over 0.99. The limits of detection were
between 0.01 and 1.0μg/kg. Matrix effects were studied by comparing solvent
calibration curves and matrix-matched calibration curves. The results indicate
the feasibility of this method for the determination of 39 pesticides in
ginseng.
Highlights
► A QuEChERS-DLLME-UPLC-MS/MS has been developed for
rapid determination of multiclass pesticide residues in ginseng. ► The procedure
to increase the sensitivity was concentration by DLLME method instead of
evaporation by nitrogen. ► This method was simple, rapid and
cheap.
15 February 2013 Publication year:
2013 Source:Journal of Chromatography B, Volumes
917–918
Eleutheroside B and Eleutheroside E, two kinds of the major
bioactive saponins of Eleutherococcus senticosus, play a pivotal role in
biologic activity. In this study, a specific and sensitive high performance
liquid chromatography–electrospray ionization-tandem mass spectrometry method
(HPLC–MS/MS) was developed and validated for simultaneous determination of
Eleutheroside B and Eleutheroside E in rat plasma. The analytes were extracted
from rat plasma via a simple protein precipitation procedure with methanol and
polygonin was used as internal standard. Chromatographic separation was achieved
on a C18 column using a gradient elution program with acetonitrile and water
containing 0.1% ammonium hydroxide solution as the mobile phase, with a flow
rate of 0.2mL/min. The detection was performed on a triple–quadrupole tandem
mass spectrometer by multiple reactions monitoring (MRM) mode in a negative ion
mode via electrospray ionization (ESI). The transition monitored were m/z 371
[M−H]− →209 for Eleutheroside B, m/z 741[M−H]− →579 for
Eleutheroside E and m/z 389[M−H]− →277 for internal standard. Linear
calibration curves were obtained in the concentration range of 1–2000ng/mL for
both (Eleutheroside B and Eleutheroside E), with a lower limit of quantification
of 1ng/mL. Extraction recovery was over 80% in plasma. The intra- and inter-day
precision (RSD) values were below 12% and accuracy (RE) was −2.80 to 5.70% at
three QC levels for both. The assay was successfully applied to study
pharmacokinetics behavior in rats after oral and intravenous administration of
the single substances (Eleutheroside B and Eleutheroside E). And further
research was performed by comparing the difference in pharmacokinetic behavior
between the single substances and an aqueous extract of E. senticosus after oral
administration. Significant difference in pharmacokinetic characteristics
between the single substances and an aqueous extract was found in rat, which
would be beneficial for the pre-clinical research and clinical use of E.
senticosus.
Highlights
► Simultaneous determination of Eleutheroside B and
Eleutheroside E in rat plasma. ► Method was validated and can be successfully
applied for pharmacokinetic study. ► Lower absolute bioavailability of
Eleutheroside B and Eleutheroside E was observed. ► Difference in PK behavior
between the single substances and an aqueous extract.
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