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1.
Tribalat L Paisse O Dessalces G Grenier-Loustalot MF 《Analytical and bioanalytical chemistry》2006,386(7-8):2161-2168
In the framework of developing analyses for exogenous contaminants in food matrices such as honey, we have compared data obtained
by high-performance liquid chromatography coupled with mass spectrometry (LC–MS) to those provided by high-performance liquid
chromatography and tandem mass spectrometry (LC–MS–MS). Initial results obtained with LC–MS showed that the technique lacked
selectivity, which is why the method was validated by LC–MS–MS. This method involves a solid-phase extraction (SPE) of nitrofuran
metabolites and nitrofuran parent drugs, a derivatization by 2-nitrobenzaldehyde for 17 h, and finally a clean-up by SPE.
The data obtained show that the limits of detection varied between 0.2 and 0.6 μg kg−1 for the metabolites and between 1 and 2 μg kg−1 for nitrofuran parent drugs. The method was applied to different flower honeys. The results showed that nitrofurans (used
as antibiotics) are consistently present in this matrix, the predominant compound being furazolidone.
Figure Working bees 相似文献
2.
Ortner K Sivanandam VN Buchberger W Müller N 《Analytical and bioanalytical chemistry》2007,388(1):173-177
Enzymatically cleaved glycans from sub-milligram quantities of erythropoietin (EPO) and ovalbumin have been analyzed, without
further purification, by two-dimensional diffusion-ordered nuclear magnetic resonance spectroscopy. At NMR sample concentrations
below 50 μmol L−1 the major components of the oligosaccharide fractions could be distinguished by their anomeric proton chemical shift and
their size-dependent diffusion coefficients.
Figure
1H NMR diffusion decay curves of anomeric protons in the EPO glycan fraction 相似文献
3.
A new spectrofluorimetric method was developed for the determination of trace amounts of lecithin using the ciprofloxacin (CIP)–terbium (Tb3+) ion complex as a fluorescent probe. In a buffer solution at pH=5.60, lecithin can remarkably reduce the fluorescence intensity of the CIP–Tb3+ complex at λ=545 nm. The reduced fluorescence intensity of the Tb3+ ion is proportional to the concentration of lecithin. Optimum conditions for the determination of lecithin were also investigated. The linear range and detection limit for the determination of lecithin were 1.0×10−6–3.0×10−5 mol L−1 and 3.44×10−7 mol L−1, respectively. This method is simple, practical, and relatively free of interference from coexisting substances. Furthermore, it has been successfully applied to assess lecithin in serum samples.
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4.
Nan Li Hui Tang Hongwei Gai Xiuling Dong Qi Wang Edward S. Yeung 《Analytical and bioanalytical chemistry》2009,394(7):1879-1885
Determination of protein surface excess is an important way of evaluating the properties of biomaterials and the characteristics
of biosensors. A single-molecule counting method is presented that uses a standard fluorescence microscope to measure coverage
of a liquid/solid interface by adsorbed proteins. The extremely low surface excess of lysozyme and bovine serum albumin (BSA),
in a bulk concentration range from 0.3 nmol L−1 (0.02 μg mL−1) to 3 nmol L−1 (0.2 μg mL−1), were measured by recording the counts of spatially isolated single molecules on either hydrophilic (glass) or hydrophobic
(polydimethylsiloxane, PDMS) surfaces at different pH. The differences observed in amounts of adsorbed proteins under different
experimental conditions can be qualitatively explained by the combined interactions of electrostatic and hydrophobic forces.
This, in turn, implies that single-molecule counting is an effective way of measuring surface coverage at a liquid/solid interface.
Figure Adsorption fraction of proteins on different surfaces changed with pH. 相似文献
5.
Determination of norfloxacin in human urine by capillary electrophoresis with electrochemiluminescence detection 总被引:3,自引:0,他引:3
A fast and sensitive approach that can be used to detect norfloxacin in human urine using capillary electrophoresis with end-column
electrochemiluminescence (ECL) detection of is described. The separation column was a 75-μm i.d. capillary. The running buffer was 15 mmol L−1 sodium phosphate (pH 8.2). The solution in the detection cell was 50 mmol L−1 sodium phosphate (pH 8.0) and 5 mmol L−1
The ECL intensity varied linearly with norfloxacin concentration from 0.05 to 10 μmol L−1. The detection limit (S/N=3) was 0.0048 μmol L−1, and the relative standard deviations of the ECL intensity and the migration time for eleven consecutive injections of 1.0 μmol L−1 norfloxacin (n=11) were 2.6% and 0.8%, respectively. The method was successfully applied to the determination of norfloxacin spiked in human
urine without sample pretreatment. The recoveries were 92.7–97.9%.
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6.
Ortega-Algar S Ramos-Martos N Molina-Díaz A 《Analytical and bioanalytical chemistry》2008,391(2):715-719
A single optosensing device based on lanthanide-sensitized luminescence was developed for determination of p-aminobenzoic acid (PABA). The method is based on the formation of a complex between PABA and Tb(III) immobilized on the solid
phase (QAE A-25 resin) placed inside the flow cell. NaCl (1 M) was used as carrier solution and HCl (0.05 M) as eluent. The
sample solutions of PABA (100 μL) containing Tb(III) and buffered at pH = 6.0 were injected into the carrier stream and the
luminescence was measured at λ
ex = 290 nm and λ
em = 546 nm. The method shows a linear range from 0.2 to 6.0 μg mL−1 with an RSD of 1.2% (n = 10) and a sampling frequency of 22 h−1. A remarkable characteristic of the method is its high selectivity which allows it to be satisfactorily applied to the analysis
of PABA in pharmaceutical samples without prior treatment.
Figure Typical emission bands of Tb(III) in a solid-phase PABA–Tb(III) luminescence spectrum 相似文献
7.
Competitive adsorption on adsorptive solid-phase microextraction (SPME) fibres implies careful determination of operating
conditions for reliable quantitative analysis of VOCs in indoor air. With this objective, two analytical approaches, involving
non-equilibrium and equilibrium extraction, were compared. The average detection limit obtained for GC-MS analysis of nine
VOCs by the equilibrium method is 0.2 μg m−3, compared with 1.9 μg m−3 with the non-equilibrium method. The effect of the relative humidity of the air on the calibration plots was studied, and
shown to affect acetone adsorption only. Hence, the concentrations that can be accurately determined are up to 9 μmol m−3. The methods were then applied to indoor air containing different concentrations of VOCs. The non-equilibrium method, involving
short extraction time, can be used for detection of pollution peaks whereas equilibrium extraction is preferable for measurement
of sub-μg m−3 ground concentration levels.
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8.
Ragno G Risoli A De Luca M Ioele G Oliverio F 《Analytical and bioanalytical chemistry》2007,389(3):923-929
A novel analytical technique able to determine the anti-ischemic drug trapidil in human serum and urine is proposed. In order
to achieve satisfactory sensitivity and selectivity, an extraction procedure was required to isolate the drug from complex
matrixes such as serum and urine. A solid-phase extraction procedure was investigated to both increase the analyte concentration
and eliminate the interfering molecules present in large amounts in both matrixes. Optimization of the extraction step was
realized by selecting a new polymeric sorbent based on a surface-modified styrene–divinylbenzene polymer which provided fast
and efficient drug extraction. Drug quantification was performed by using the third-order derivative spectra of the SPE eluates.
Absorbance specific signals at 3D335,316 and 3D316 nm for urine and serum, respectively, were demonstrated to be directly proportional to drug concentration and barely affected
by residual matrix interferences. Under the optimized experimental conditions the calibration plots were linear over the concentration
range 0.2–50 μg mL−1. The method was validated by analysis of a series of spiked samples. Accuracy (recovery of 95 and 94% for serum and urine,
respectively) and precision (RSD below 4%) were good.
Figure Assay of Trapidil in biological fluids by SPE and derivative spectrophotometry 相似文献
9.
Nanostructured electrochemical DNA biosensors for detection of the effect of berberine on DNA from cancer cells 总被引:2,自引:0,他引:2
Ovádeková R Jantová S Letasiová S Stepánek I Labuda J 《Analytical and bioanalytical chemistry》2006,386(7-8):2055-2062
Multi walled carbon nanotubes (MWNT) in dimethylformamide (DMF) or aqueous sodium dodecyl sulfate (SDS) solution, colloidal
gold nanoparticles (GNP) in phosphate buffer solution (PBS), and a GNP–MWNT mixture in aqueous SDS solution have been investigated
for chemical modification of a screen-printed carbon electrode used as the signal transducer of a dsDNA-based biosensor. Differential
pulse voltammetry of the DNA redox marker and the guanine moiety anodic oxidation and cyclic voltammetry with K3[Fe(CN)6] as indicator revealed substantial enhancement of the response of the biosensor, particularly when MWNT in SDS solution was
used. The biosensor was used in testing of berberine, an isoquinoline plant alkaloid with significant antimicrobial and anticancer
activity. Berberine had a very strong, concentration-dependent, effect on the structural stability of DNA from the human cancer
cells (U937 cells) whereas non-cancer cells were changed only when berberine concentrations were relatively high 75 and 50 μg
mL−1.
Figure Schematic illustration of preparation of the nanostructured films: (a) layer-to-layer coverage (DNA/nanomaterial/SPE); (b) mixed coverage (DNA-nanomaterial/SPE) 相似文献
10.
Pérez-Sirvent C Martínez-Sánchez MJ García-Lorenzo M López-García I Hernández-Córdoba M 《Analytical and bioanalytical chemistry》2007,388(2):495-498
Use of small membrane pumps, instead of peristaltic pumps, to introduce sample and reagent solutions into the spectrometer
has several advantages in atomic fluorescence spectrometric determination of mercury. This simple modification results in
a substantial saving in the time required for the measurements and so 90% of reagent solution volumes and 95% of sample solution
volumes are saved, with a consequent decrease in the volume of waste generated. The sampling frequency is almost tripled,
with no deterioration in sensitivity, which is similar to that obtained by use of peristaltic pumps. The relative standard
deviation for ten consecutive measurements of a 1 μg L−1 mercury solution was approximately 2%.
Figure Small membrane pumps for the atomic fluorescene spectro metric determination of mercury 相似文献
11.
Analytical procedure for determination of the time profile of eprinomectin excretion in sheep faeces
Kozuh Erzen N Hodoscek L Cerkvenik-Flajs V 《Analytical and bioanalytical chemistry》2007,387(4):1329-1335
An analytical procedure has been introduced to enable study of the time profile of eprinomectin excretion in sheep faeces.
Eprinomectin was extracted from sheep faeces with acetonitrile, the extract was cleaned by solid-phase extraction (SPE), and,
after derivatization by reaction with N-methylimidazole, trifluoroacetic anhydride, and acetic acid, eprinomectin was analysed by high-performance liquid chromatography
(HPLC) with fluorescence detection. The method has a low detection limit (1.0 ng g−1 of moist sheep faeces), a low quantification limit (2.5 ng g−1 of moist sheep faeces), good recovery (in the range 78.8 to 87.1%), and good reproducibility (RSD<10%). The method was used
to study the time-profile of excretion of eprinomectin in sheep faeces after a single topical administration of 0.5 mg kg−1 b.w. of the drug. Because of its good recovery, precision, and sensitivity, the method has also proved applicable to further
ecotoxicological studies of eprinomectin.
Figure Autochthonous Slovenian dairy breed sheep – Istrian Pramenka 相似文献
12.
Water-soluble cadmium sulfide (CdS) quantum dots (QDs) capped by mercaptoacetic acid were synthesized by aqueous-phase arrested
precipitation, and characterized by transmission electron microscopy, spectrofluorometry, and UV-Vis spectrophotometry. The
prepared luminescent water-soluble CdS QDs were evaluated as fluorescence probes for the detection of highly reactive hydrogen
selenide ions (HSe− ions). The quenching of the fluorescence emission of CdS QDs with the addition of HSe− ions is due to the elimination of the S2− vacancies which are luminescence centers. Quantitative analysis based on chemical interaction between HSe− ions and the surface of CdS QDs is very simple, easy to develop, and has demonstrated very high sensitivity and selectivity
features. The effect of foreign ions (common anions and biologically relevant cations) on the fluorescence of the CdS QDs
was examined to evaluate the selectivity. Only Cu2+ and S2− ions exhibit significant effects on the fluorescence of CdS QDs. With the developed method, we are able to determine the
concentration of HSe− ions in the range from 0.10 to 4.80 μmol L−1, and the limit of detection is 0.087 μmol L−1. The proposed method was successfully applied to monitor the obtained HSe− ions from the reaction of glutathione with selenite. To the best of our knowledge, this is the first report on fluorescence
analysis of HSe− ions in aqueous solution.
Figure CdS quantum dots as fluorescence probes for the sensitive and selective detection of highly reactive HSe- ions in aqueous
solution 相似文献
13.
Gergely A Szász G Szentesi A Gyimesi-Forrás K Kökösi J Szegvári D Veress G 《Analytical and bioanalytical chemistry》2006,384(7-8):1506-1510
The biological importance of dehydroepiandrosterone (DHEA) is reflected by the fact that DHEA is a crucial precursor of the biosynthesis of the steroidal sex hormones. Simultaneous separation of DHEA, dehydroepiandrosterone sulfate (DHEA-S), pregnenolone, androstenedione and testosterone has been accomplished by reversed-phase ion-pair high-performance liquid chromatography (RP-IP-HPLC) based on isocratic elution applying circular dichroism (CD) detection at 295 nm. Addition of tetrabutylammonium hydrogensulfate to the mobile phase increases the retention of DHEA-S on the C8-silica column by an apparent ion-pairing mechanism without affecting the retention of the other (non-ionic) steroids. CD spectroscopy provides highly selective detection of compounds possessing optically active absorption bands and the separation is even more selective in the higher wavelength range applied. The linearity of the steroid concentration (c, mg mL−1) versus peak area was tested in the concentration range of 0.5–2 mg mL−1 (injected quantities were 10–40 μg). The relative standard deviation (RSD) values for DHEA and DHEA-S indicated a good intra-assay and inter-assay precision of the method.
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14.
Lee KC Cheuk MW Chan W Lee AW Zhao ZZ Jiang ZH Cai Z 《Analytical and bioanalytical chemistry》2006,386(7-8):2225-2232
A reversed-phase HPLC method has been developed for determination of twelve intact glucosinolates—glucoiberin, glucocheirolin,
progoitrin, sinigrin, epiprogoitrin, glucoraphenin, sinalbin, gluconapin, glucosibarin, glucotropaeolin, glucoerucin, and
gluconasturtiin—in ten traditional Chinese plants. The samples were extracted with methanol and the extracts were cleaned
on an activated Florisil column. A mobile phase gradient prepared from methanol and 30 mmol L−1 ammonium acetate at pH 5.0 enabled baseline separation of the glucosinolates. Glucosinolate detection was confirmed by quadrupole
time-of-flight tandem mass spectrometric analysis in negative-ionization mode. Detection limits ranged from 0.06 to 0.36 μg
g−1 when 5 g of dried plant was analyzed. Recoveries of the glucosinolates were better than 85% and precision (relative standard
derivation, n = 3) ranged from 5.3 to 14.6%. Analysis of the glucosinolates provided scientific evidence enabling differentiation of three
pairs of easily confused plants.
Figure Glucosinolates Analysis for the Differentiation of Easily-Confusing Herbs 相似文献
15.
A method based on use of functionalized gold nanoparticles on polyethylenimine film has been developed for colorimetric detection of immunoglobulin G (IgG). The immunogold nanoparticles were immobilized on quartz slides by recognition between antibody and antigen, with the antigen chemically adsorbed on the polyethylenimine film. By measurement of the UV–visible spectra of the immobilized immunogold, detection of h-IgG was achieved. The detection limit for h-IgG by use of this method can be as low as 0.01 μg mL−1. This method is quite promising for numerous applications in immunoassay.
Figure 相似文献
16.
A rapid, specific, and sensitive method has been developed using molecularly imprinted polymers (MIPs) as solid-phase extraction
sorbents for extraction of trace tetracycline antibiotics (TCs) in foodstuffs. MIPs were prepared by precipitation polymerization
using tetracycline as the template. Under the optimal condition, the imprinting factors for MIPs were 4.1 (oxytetracycline),
7.0 (tetracycline), 7.4 (chlortetracycline), 7.7 (doxycycline), respectively. Furthermore, the performance of MIPs as solid-phase
extraction sorbents was evaluated and high extraction efficiency of molecularly imprinted solid-phase extraction (MISPE) procedure
was demonstrated. Compared with commercial sorbents, MISPE gave a better cleanup efficiency than C18 cartridge and a higher
recovery than Oasis HLB cartridge. Finally, the method of liquid chromatography–tandem mass spectrometry coupled with molecular-imprinted
solid-phase extraction was validated in real samples including lobster, duck, honey, and egg. The spiked recoveries of TCs
ranged from 94.51% to 103.0%. The limits of detection were in the range of 0.1–0.3 μg kg−1.
Chromatograms obtained by direct injection of the spiked egg extracts (5 × 10-3 mmol L−1) and purification with MISPE 相似文献
17.
The application of near-infrared (NIR) dyes (λ
em > 750 nm) to the analysis of biological samples shows much promise, because the long emission wavelengths of such dyes allow
interferences from biomolecule matrices to be minimized. In this paper, a novel NIR dye, 5,5′-dicarboxy-1,1′-disulfobutyl-3,3,3′,3′-tetramethylindotricarbocyanine
(DCDSTCY) has been developed for the spectrophotometric determination of total protein in serum. Under acidic conditions,
the binding of DCDSTCY to proteins caused a new peak at 878 nm, the height of which was proportional to the concentration
of protein. The linear range of the method was found to be 0.04–0.5 μg mL−1 for bovine serum albumin (BSA) and human serum albumin (HSA), and detection limits of 5 ng mL−1 were obtained for these substances. The maximum binding number of BSA with DCDSTCY was measured to be 133. The method proposed
here has been applied to the quantitation of total protein in serum, and recoveries of 96.6–104% were achieved.
Figure Near-infrared probe for protein determination 相似文献
18.
Du D Huang X Cai J Zhang A Ding J Chen S 《Analytical and bioanalytical chemistry》2007,387(3):1059-1065
A simple method has been devised for immobilization of acetylcholinesterase (AChE)—covalent bonding to a multiwall carbon
nanotube (MWNT)–cross-linked chitosan composite (CMC)—and a sensitive amperometric sensor for rapid detection of acetylthiocholine
(ATCl) has been based on this. Fourier-transform infrared spectroscopy proved that the native structure of the immobilized
enzyme was preserved on this chemically clean and homogeneous composite film, because of the excellent biocompatibility and
non-toxicity of chitosan. Glutaraldehyde was used as cross-linker to covalently bond the AChE, and efficiently prevented leakage
of the enzyme from the film. Because of the inherent conductive properties of the MWNT, the immobilized AChE had greater affinity
for ATCl and excellent catalytic effect in the hydrolysis of ATCl, with a value of 132 μmol L−1, forming thiocholine, which was then oxidized to produce a detectable and rapid response. Under optimum conditions the amperometric
current increased linearly with the increasing concentration of ATCl in the range 2.0–400 μmol L−1, with a detection limit of 0.10 μmol L−1. Fabrication reproducibility of the sensor was good and the stability was acceptable. The sensor is a promising new tool
for characterization of enzyme inhibitors and for pesticide analysis.
Abstract 相似文献
19.
Zaher M Ravelet C Baussanne I Ravel A Grosset C Décout JL Peyrin E 《Analytical and bioanalytical chemistry》2009,393(2):655-660
In this paper, we describe the preparation and the evaluation of a porous graphitic carbon (PGC) column coated with a new
dinaphthyl derivative of neamine for chiral ligand-exchange (LE) chromatography. It was shown that the graphitic surface/dinaphthyl
anchor system efficiently (1.15 μmol/m2) and stably (three months of intensive use) adsorbs the neamine template onto the chromatographic support. The resulting
coated PGC stationary phase showed appreciable LE-based enantioselective properties towards several native amino acids.
Chromatographic separation of methionine enantiomers using a dinaphtyl neamine-based ligand-exchange chiral stationary phase 相似文献
20.
Destandau E Lefèvre JP Chouai Fakhr Eddine A Desportes S Jullien MC Hierle R Leray I Valeur B Delaire JA 《Analytical and bioanalytical chemistry》2007,387(8):2627-2632
A microfabricated device has been developed for fluorimetric detection of potassium ions without previous separation. It is
based on use of a fluorescent molecular sensor, calix–bodipy, specially designed to be sensitive to and selective for the
target ion. The device is essentially made of a Y-shape microchannel moulded in PDMS fixed on a glass substrate. A passive
mixer is used for mixing the reactant and the analyte. The optical detection arrangement uses two optical fibres, one for
excitation by a light-emitting diode, the other for collection of the fluorescence. This system enabled the flow-injection
analysis of the concentration of potassium ions in aqueous solutions with a detection limit of 0.5 mmol L−1 and without interference with sodium ions. A calibration plot was constructed using potassium standard solutions in the range
0–16 mmol L−1, and was used for the determination of the potassium content of a pharmaceutical pill.
Figure Photography of the microfluidic channel showing the ridges in the PDMS substrate at the top of the channel 相似文献