共查询到20条相似文献,搜索用时 31 毫秒
1.
Webb A 《Analytical and bioanalytical chemistry》2007,388(3):525-528
Figure Schematic diagram of a typical arrangement used for hyphenating chemical microseparations (e.g. capillary HPLC, CE, or CEC)
with microcoil NMR detection 相似文献
2.
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
3.
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
4.
A novel headspace solid-phase microextraction method for the exact determination of organochlorine pesticides in environmental soil samples 总被引:2,自引:0,他引:2
Zhao R Wang X Yuan J Jiang T Fu S Xu X 《Analytical and bioanalytical chemistry》2006,384(7-8):1584-1589
A novel method of determining organochlorine pesticides (OCPs) is described. It is based on solid-phase microextraction (SPME) and gas chromatography–electron capture detection. During the development of the method, soil samples were prepared, spiked with standard solution, and then aged for some time. Extraction conditions such as the extraction time, the NaCl content, the volume of water, the extraction temperature and the desorption time were investigated and optimized. The limits of detection obtained using the method ranged from 0.10 to 0.51 ng g−1, and relative standard deviations were lower than 10% for most organochlorine pesticides. Real soil samples were successfully analyzed using the proposed method. The results from the method developed here were in good agreement with those obtained using ultrasonic extraction. The result demonstrates that aging soils spiked with standard solution is an important method development step, because the soil samples obtained using this approach are more like real soils than those obtained when aging is not used.
相似文献
5.
Pérez Pavón JL García Pinto C Guerrero Peña A Moreno Cordero B 《Analytical and bioanalytical chemistry》2008,391(2):599-607
In the present work we report the results obtained with a methodology based on direct coupling of a headspace generator to
a mass spectrometer for the identification of different types of petroleum crudes in polluted soils. With no prior treatment,
the samples are subjected to the headspace generation process and the volatiles generated are introduced directly into the
mass spectrometer, thereby obtaining a fingerprint of volatiles in the sample analysed. The mass spectrum corresponding to
the mass/charge ratios (m/z) contains the information related to the composition of the headspace and is used as the analytical signal for the characterization
of the samples. The signals obtained for the different samples were treated by chemometric techniques to obtain the desired
information. The main advantage of the proposed methodology is that no prior chromatographic separation and no sample manipulation
are required. The method is rapid, simple and, in view of the results, highly promising for the implementation of a new approach
for oil spill identification in soils.
Figure PCA score plots illustrate clear discrimination of types of crude oil in polluted soil samples (e.g. results are shown for
vertisol) 相似文献
6.
An X-ray fluorescence method (XRF) is presented that allowed low detection limits (at the 0.1–23 ng mL−1 level) to be obtained for Cr, Mn, Fe, Ni, Zn, Sr, Pb, Bi and Br in water. The samples were prepared using a thin layer method. Trace elements were determined via the calibration curve and standard addition. Absorption effects and inhomogenities in prepared samples were checked for using the emission–transmission method and internal standards, respectively. The results from the XRF method were compared with the results from the inductively coupled plasma atomic emission spectrometry method.
相似文献
7.
We report on a highly sensitive competitive immunoassay for the mycotoxin Ochratoxin (OTA) using magnetic silica nanoparticles (NPs) fluorescently labeled with rhodamine 123 (Rho123) as signal intensifier. The method is based on the measurement of fluorescence resonance energy transfer (FRET) that occurs from CdTe quantum dots covered with anti-OTA antibody to the dye Rho123 on the surface of the NPs. The immunoreaction between anti-OTA antibody and OTA brings the fluorophore (acting as the acceptor) in close proximity of the QDs (acting as the donor), and this causes FRET to occur upon photo-excitation of the QDs. The size and polydispersity of the silica coated magnetic NPs was studied via TEM. The method has a detection limit of 0.8 pg of OTA per mL. It was applied to the determination of OTA in spiked human serum. A linear relationship is found between the increase in the fluorescence intensity of Rho 123 at 580 nm and the concentration of OTA in spiked samples over the 8 to 48 pg?mL?1 concentration range. This highly sensitive homogeneous competitive detection scheme is simple, rapid and efficient. It does not require multiple separation steps and excessive washing. 相似文献
8.
Marco Frasconi Monica Mazzarino Francesco Botrè Franco Mazzei 《Analytical and bioanalytical chemistry》2009,394(8):2151-2159
In this paper, we present a surface-plasmon-resonance-based immunosensor for the real-time detection of cortisol and cortisone
levels in urine and saliva samples. The method proposed here is simple, rapid, economic, sensitive, robust, and reproducible
thanks also to the special features of the polycarboxylate-hydrogel-based coatings used for the antibody immobilization. The
sensor surface displays a high level of stability during repeated regeneration and affinity reaction cycles. The immunosensor
shows high specificity for cortisol and cortisone; furthermore, no significant interferences from other steroids with a similar
chemical structure have been observed. The suitability of the hydrogel coating for the prevention of nonspecific binding is
also investigated. A good correlation is noticed between the results obtained by the proposed method and the reference liquid
chromatography/tandem mass spectrometry method for the analysis of cortisol and cortisone in urine and saliva samples. Standard
curves for the detection of cortisol and cortisone in saliva and urine are characterized by a detection limit less than 10 μg l−1, sufficiently sensitive for both clinical and forensic use.
Application of a newly developed SPR immunosensor for the measurement of cortisol in anti-doping analysis 相似文献
9.
A universal hepatitis B virus (HBV) DNA detection kit is appealing for the worldwide diagnosis and monitoring of the treatment
of different mutant types of hepatitis B virus. A sensitive and reproducible real-time PCR assay based on the universal molecular
beacon (U-MB) technique was developed for the detection of HBV DNA in serum. The U-MB probe used in the assay has no interaction
with the HBV DNA sequence. The U-MB technique not only reduced the cost of HBV detection but also had the potential for the
development of a universal detection kit for different mutant HBV types and other DNA systems. To demonstrate its clinical
utility, 90 serum samples were analyzed using the U-MB real-time PCR method. In the experiments we found that several crucial
factors needed to be considered in the primer design, such as the avoidance of formation of severe primer–dimer and primer
self-hairpin structure. With the optimized primer sets, satisfactory results were obtained for all the tested samples. We
concluded that this assay would be an excellent candidate for a universal HBV DNA detection method.
Principle of the U-MB real-time PCR method for HBV DNAdetection 相似文献
10.
Ferreira CS Papamichael K Guilbault G Schwarzacher T Gariepy J Missailidis S 《Analytical and bioanalytical chemistry》2008,390(4):1039-1050
Aptamers are functional molecules able to bind tightly and selectively to disease markers, offering great potential for applications
in disease diagnosis and therapy. MUC1 is a well-known tumour marker present in epithelial malignancies and is used in immunotherapeutic
and diagnostic approaches. We report the selection of DNA aptamers that bind with high affinity and selectivity an MUC1 recombinant
protein containing five repeats of the variable tandem repeat region. Aptamers were selected using the SELEX methodology from
an initial library containing a 25-base-long variable region for their ability to bind to the unglycosylated form of the MUC1
protein. After ten rounds of in vitro selection and amplification, more than 90% of the pool of sequences consisted of target-binding
molecules, which were cloned, sequenced and found to share no sequence consensus. The binding properties of these aptamers
were quantified using ELISA and surface plasmon resonance. The lead aptamer sequence was subsequently used in the design of
an aptamer–antibody hybrid sandwich ELISA for the identification and quantification of MUC1 in buffered solutions. Following
optimisation of the operating conditions, the resulting enzyme immunoassay displayed an EC50 value of 25 μg/ml, a detection limit of 1 μg/ml and a linear range between 8 and 100 μg/ml for the MUC1 five tandem repeat
analyte. In addition, recovery studies performed in buffer conditions resulted in averaged recoveries between 98.2 and 101.7%
for all spiked samples, demonstrating the usability of the aptamer as a receptor in microtitre-based assays. Our results aim
towards the formation of new diagnostic assays against this tumour marker for the early diagnosis of primary or metastatic
disease in breast, bladder and other epithelial tumours.
Figure An aptamer-antibody two-dimentional immunoassay for MUC1 相似文献
11.
Llamas NM Stewart L Fodey T Higgins HC Velasco ML Botana LM Elliott CT 《Analytical and bioanalytical chemistry》2007,389(2):581-587
The mouse bioassay is the methodology that is most widely used to detect okadaic acid (OA) in shellfish samples. This is one
of the best-known toxins, and it belongs to the family of marine biotoxins referred to as the diarrhetic shellfish poisons
(DSP). Due to animal welfare concerns, alternative methods of toxin detection are being sought. A rapid and specific biosensor
immunoassay method was developed and validated for the detection of OA. An optical sensor instrument based on the surface
plasmon resonance (SPR) phenomenon was utilised. A polyclonal antibody to OA was raised against OA–bovine thyroglobulin conjugate
and OA–N-hydroxy succinimide ester was immobilised onto an amine sensor chip surface. The assay parameters selected for the analysis
of the samples were: antibody dilution, 1/750; ratio of antibody to standard, 1:1; volume of sample injected, 25 μl min−1; flow rate, 25 μl min−1. An assay action limit of 126 ng g−1 was established by analysing of 20 shellfish samples spiked with OA at the critical concentration of 160 ng g−1, which is the action limit established by the European Union (EU). At this concentration of OA, the assay delivered coefficient
of variations (CVs) of <10%. The chip surface developed was shown to be highly stable, allowing more than 50 analyses per
channel. When the concentrations of OA determined with the biosensor method were compared with the values obtained by LC–MS
in contaminated shellfish samples, the correlation between the two analytical methods was found to be highly satisfactory
(r
2 = 0.991).
Figure Biacore 相似文献
12.
A simple method using an unmodified edge plane pyrolytic graphite electrode (EPPGE) is reported for the simultaneous determination
of dopamine (DA), serotonin (ST) and ascorbic acid (AA). The performance of this electrode is superior to other unmodified
carbon-based electrodes and also to many modified electrodes in terms of detection limit, sensitivity and peak separation
for determination of DA, ST and AA. Using this method, detection limits of 90 nM, 60 nM and 200 nM were obtained for DA, ST
and AA respectively. No electrode fouling is observed during a set of experiments and good sensitivity is obtained for the
simultaneous determination of DA, ST and AA. The peaks for the three species are well resolved from each other and the electrode
is successfully utilised for their determination in standard and real samples.
相似文献
13.
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
14.
The catalyzed reporter deposition (CARD) method of signal amplification, also called “tyramide signal amplification”, has
been used in immunoassays not only to increase sensitivity but also to reduce assay time. The current approach to tyramide
amplification in immunoassays involves slow incubation with agitation. In this paper we describe new filtration-based tyramide
amplification and substrate visualization techniques. Compared with the standard method, this new approach greatly enhances
spot intensities in membrane immunoassay and reduces biotinylated tyramide (B-T) and substrate consumption approximately fiftyfold,
without loss of specificity. An improved test device and a cost-effective method for preparation of membranes for Super-CARD
amplification have also been developed. The techniques have been used for rapid detection of aflatoxin B1 (AFB1) in a variety of foodstuffs with a detection limit of 12.5 μg kg−1. The assay procedure involves sequential addition of standards or sample, AFB1–horseradish peroxidase (HRP) conjugate, B-T, avidin–HRP, and substrate solution over anti-AFB1 antibody-spotted zones of the membrane surface. The method saves time, improves reproducibility, eliminates many washing
steps and avoids manipulation of the membranes between the different steps, while maintaining the sensitivity of the standard
method. Average recoveries from different non-infected food samples spiked with AFB1 at concentrations from 25 to 100 mg kg−1 were between 95 and 105%. AFB1 results obtained on different days for Aspergillus parasiticus infection of corn and groundnut samples correlated well with estimates obtained by HPLC.
Figure The principle of filtration-based tyramide filtration technique 相似文献
15.
16.
A novel method for rapid separation and determination of ascorbic acid and uric acid has been developed with a polycation-modified
poly(dimethylsiloxane) (PDMS) microchip under a negative-separation electric field. Just by flushing the microchip with aqueous
solutions of the polycations, poly(allylamine) hydrochloride, poly(diallyldimethylammonium chloride) or chitosan could be
stably coated on the PDMS microchannel surface, which resulted in a reversed electroosmotic flow and thus the rapid and efficient
separation of the two substrates. Factors influencing the separation, including polycation category, buffer solution, detection
potential and separation voltage, were investigated and optimized. The cheapness, rapid analysis speed and the successful
analysis of human urine make this microsystem attractive for application in clinics.
Figure The electropherograms of 100 μ/mL AA and UA in (1) PAH, (2) PDDA, (3) Chitosan modified PDMS microchannels and native PDMS
microchip (4). 相似文献
17.
A method is described for determination of residues of the insecticide Etofenprox in environmental samples. Anionic surfactant
micelle-mediated extraction (coacervation extraction) was evaluated for isolation of Etofenprox before HPLC. The optimum conditions
used for extraction included: 0.09 g sodium dodecanesulfonate (SDoS), 3.1 mL (3.3, for concentrations below 0.04 mg L−1) 12 mol L−1 HCl, 5 min vortex stirring, 5 min centrifugation at 4000 rpm, 2 h equilibration time. The limits of quantification (LOQ)
and detection (LOD) were 0.01 and 0.004 mg L−1, respectively, and recoveries obtained from five real samples ranged from 94.33±2.48 to 100.13±2.71%. The precision of the
method was good; relative standard deviations (RSD) were less than 7%.
相似文献
18.
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
19.
Ma X Zhu T Xu H Li G Zheng J Liu A Zhang J Du H 《Analytical and bioanalytical chemistry》2008,390(4):1133-1137
A chemical prototype sensor was constructed based on nanofiber-structured TiO2 and highly sensitive quartz resonators. The gas-sensing behavior of this new sensor to selected simulant warfare agents was
investigated at room temperature. Results showed rapid response and good reversibility of this sensor when used with high-purity
nitrogen. This provides a simple approach to preparation of materials needed as chemical sensors for selected organic volatiles
or warfare agents.
Figure Sensing behavior of TiO2 nanofiber sensor to chemical vapors 相似文献
20.
Surmeian A Diplasu C Groza A Ganciu M Belenguer P Tempez A Chapon P 《Analytical and bioanalytical chemistry》2007,388(8):1625-1629
A high-current pulsed hollow cathode discharge was used to study the role of atomic and ionic metastables involved in ionization
plasma processes. We observed the enhancement of the spectral emission lines of noble gas ions in the afterglow. A study of
the processes that involve atomic and ionic metastables is of great interest since it should lead to a better understanding
of and enhanced control over the ionization mechanisms crucial to analytical glow discharge mass spectrometry (GDMS) analysis.
Figure Time profile of Ti, Ti+, and Ne+ spectral lines 相似文献