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1.
M. A. González-Martínez S. Morais R. Puchades A. Maquieira M. P. Marco D. Barceló 《Fresenius' Journal of Analytical Chemistry》1998,361(2):179-184
Intensive agriculture associated with the use of large amounts of different pesticides, together with the growing concern
about the potential contamination of ground water, have brought about the need for developing fast screening methods. This
work presents the automation of an enzyme-linked immunosorbent assay for atrazine by means of a flow-through system. Three
different solid supports for antibody immobilization were compared in a direct competitive assay format. Sensitivity reached
in all cases was below the maximum level allowed in the EU (100 ng L–1). Cross-reactivity of atrazine-related compounds was also studied. The performance of the different supports is discussed
regarding sensitivity and immunosurface regeneration.
Received: 21 July 1997 / Revised: 7 November 1997 / Accepted: 11 November 1997 相似文献
2.
α-MSH was labelled at its tyrosine2 residue with tritium and iodine. Several synthetic routes were investigated by preparing 13 precursor or mode compounds and 4 different labelled products (via about 40 intermediates). Their melanotropic activity was determined with an in vitro frog skin assay and, for some of the compounds, with a tyrosinase assay. The tritiation was performed on [Tyr(I2)2]α-MSH by catalytic halogen/tritium exchange, yielding α-MSH of high specific radioactivity (34 Ci/mmol) and full biological activity. Iodination was studied in detail using five different techniques. An equimolar chloramine T procedure proved to be the most convenient and reproducible method, resulting in monoiodinated α-MSH containing 99% of the label in position 2. The biological activity was 50% that of α-MSH; the specific radioactivity, determined in a competitive binding assay with a highly specific α-MSH antiserum and [Tyr(I)2]α-MSH as competitor, was 1530 Ci/mmol. The labelling techniques and the bioligical results are discussed. 相似文献
3.
Two composite supports with a mixed inorganic–organic structure were synthesized: BTAl and UTAl. Hydrophilic–hydrophobic dual properties of the supports were suitable for preparing egg-shell-supported metal catalysts for selective hydrogenation reactions. The catalysts were characterized by ICP, XRD, OM, TEM, EPMA, XPS and TGA. Their mechanical resistance was assessed. Activity and selectivity were tested with the hydrogenation of 2,3-butanedione (diacetyl) to 3-hydroxy-2-butanoneacetoin (acetoin). The same order of increasing metal particle size was found for the two tested supports: Pt < Ru < Pd. The XPS analysis showed that the metal/composite catalysts reduced in H2 at 503 K had two kinds of active sites: reduced (Me°) and electron-deficient (Me+). It was rationalized that the hydrogen bond cleavage was performed on the Me° active sites, while reactant adsorption occurred on the Me+ sites. The differences in activity and selectivity between the composite catalysts were attributed to electronic effects on the different metals and to different adsorptive properties of the different polymers. The high selectivity to acetoin was attributed to the preferential adsorption of diacetyl as compared to the adsorption of acetoin. The BTAl catalysts were slightly more active and selective than the UTAl ones. This was attributed to electronic effects caused by remnant organic groups on the composite supports (urethane or biphenyl on UTAl or BTAl, respectively). Pd-BTAl was the most active and selective catalyst, a fact related to electronic effects of both palladium and the support. 相似文献
4.
In this study, the uniaxial pressing method was employed to fabricate low-cost ceramic membrane supports using inexpensive clays for microfiltration applications. The primary precursors used to make different membrane supports (S1–S3) were Ball clay and China clay. Thermogravimetric analysis (TGA), particle size distribution (PSD), contact angle measurements, X-ray diffraction (XRD), and scanning electron microscopy (SEM) were performed in addition to water flux, porosity, water permeability, and average pore size measurements to characterize the membrane. SEM analysis revealed that the surface morphology of the membrane supports varies significantly depending on the raw material composition. The contact angle analysis of the supports revealed that they are hydrophilic, which is suitable for microfiltration applications. The water permeability, average pore size, and porosity of the membrane supports (S1–S3) were 4.31 × 10?6 – 2.77 × 10?6 m3/m2s kPa, 1.18–0.31 μm, 44–41%, respectively. Furthermore, the membranes' high pH and chlorine resistance show their suitability for use in harsh chemical cleaning. The production cost of membranes based on raw materials, pressing, and sintering was estimated to be Rs.1319/m2 ($17.07), Rs. 978/m2 ($12.66) and Rs. 924/m2 ($11.96) for the supports S1, S2, and S3, respectively. Thus, membrane supports with low-cost clay materials are now suggested for microfiltration applications. 相似文献
5.
Philemon E. Tyllianakis Sotiris E. Kakabakos Gregory P. Evangelatos Dionyssis S. Ithakissios 《Applied biochemistry and biotechnology》1993,38(1-2):15-25
The several factors that could affect the sensitivity and the accuracy of the determination of solid-supported amino groups using 2-iminothiolane (Traut's reagent) and 5,5′-dithiobis-(2-nitrobenzoic acid) (Ellman's reagent) are described. The authors found that by using 0.1M phosphate buffer, pH 8.0, instead of ethanol as solvent for the reaction of the solid supports with the 2-iminothiolane, using 0.1M phosphate buffer adjusted at pH 7.27 instead of 8.0 as diluent of 5,5′-dithiobis-(2-nitrobenzoic acid), and selecting carefully the concentration of the latter reagent, it was possible to produce a very sensitive assay capable of quantitatively determining the surface amino groups of very different types of samples. The assay is well adapted for quantitative determination of amino-carrying plastic beads, permitting the determination of nanomolar quantities. In addition, the assay is well suited for microparticulated solid supports (e.g., AH-Sepharose). 相似文献
6.
The contribution of different MgO supports to the coordination polymerization of ethylene was studied by x-ray diffractometry and infrared (IR) and electron spin resonance (ESR) spectroscopy of the supports and their products after treatment with TiCl4. It was concluded that TiCl4 was bonded on the surface OH groups of MgO mainly in inactive form, whereas the majority of the active sites was associated with the coordinatively unsaturated O2? ions. 相似文献
7.
Sotiris E. Kakabakos Philemon E. Tyllianakis Gregory P. Evangelatos Dionyssis S. Ithakissios 《Applied biochemistry and biotechnology》1996,56(1):95-109
We describe new colorimetric methods for the determination of the reactive and available solid-supported carboxylic,N-hydroxysuc cinylated carboxylic, and aldehydo groups under conditions usually applied for the coupling of biomolecules. The
methods involve the reaction of the solid-supported functional groups with tyramine or cysteine, and the subsequent titration
of the ligand coupled onto the solid supports using the commercially available bicinchoninic acid/copper protein assay reagent
(BCA). The titration is based on the ability of these ligands to reduce Cu2+ to Cu+, which forms a chelate complex with bicinchoninic acid absorbing at 562 nm. The quantita tion is finally carried out through
standard curves obtained using tyramine or cysteine solutions of known concentrations. The values obtained by the assays developed
for several solid supports carrying carboxylic, NHS-ester, and aldehydo groups were well correlated with those obtained by
other literature methods or provided by the manu facturers. All of the proposed methods are simple, more sensitive than other
relevant literature methods, and require only commericially available reagents. 相似文献
8.
《Journal of Saudi Chemical Society》2022,26(4):101512
In wastewater treatment, the development of low-cost separation methods is of significant importance. Low-cost membranes based on natural materials have become a highly active research topic in recent years. Herein, using low-cost natural Moroccan sand, new ceramic supports have been developed and characterized using different techniques such as X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), differential thermal analysis (DTA), along with scanning electron microscope (SEM). Plastic paste (average particle size ≤125 µm) was blended with organic additives and water, then the obtained paste was extruded into porous tubular supports. The support had a porosity of 43%, water permeability of 1928 L/h m2 bar, excellent chemical and mechanical properties and an average pore diameter in the range of 8–15 µm after firing at 950 °C/2 h. As per SEM analysis, the tubular supports had a smooth and crack-free surface. The slip casting process was used to create a microfiltration layer from the same natural sand powder (average particle size ≤63 µm) using a mixture of powder sand, water, and polyvinyl alcohol solution. The water permeability of the microfiltration membrane sintered at 950 °C/2 h was 1052 L/h m2 bar, the average pore size diameter was about 0.90 µm and 82% of pores had a diameter ≤1.00 µm. The obtained microfiltration membrane was tested for the treatment of urban wastewater. The membrane showed excellent separation performance in turbidity removal and chemical oxygen demand. 相似文献
9.
Immunoenzyme assay of nonylphenol: study of selectivity and detection of alkylphenolic non-ionic surfactants in water samples 总被引:1,自引:0,他引:1
Mart'ianov AA Dzantiev BB Zherdev AV Eremin SA Cespedes R Petrovic M Barcelo D 《Talanta》2005,65(2):367-374
Immunoenzyme assay (ELISA) is proposed and characterized for determination of alkylphenol ethoxylates, a primary class of manufactured non-ionic surfactants. The assay is based on the obtained polyclonal antibodies against nonylphenol (NP), the main stable intermediate of the decomposition of nonylphenol ethoxylates. A mixture of non-modified branched isomers of NP was applied as hapten coupled to protein carriers by Mannich reaction with the use of formaldehyde. The proposed ELISA format is based on immobilized NP-(soybean trypsin inhibitor) conjugate as a competitor of antigen molecules contained in the tested sample for binding with specific antibodies indirectly labeled via an anti-species immunoperoxidase conjugate. The developed ELISA allows to reveal NP with the limit of detection about 10 ng ml−1 and NP-related compounds such as octylphenol, alkylphenoletoxylates, alkylphenolcarboxylates and their halogenated derivatives. The ELISA was applied for assaying polluted water samples, namely influents and effluents from different wastewater treatment plants (WWTP) and tap water. ELISA and chromatographic data demonstrate good correlation (r = 0.94), while ELISA gives higher values. Due to endocrine disrupting and other toxic activities of some metabolites of alkylphenolic non-ionic surfactants, the developed assay may be effectively used in ecological monitoring and sanitary control. 相似文献
10.
The development of a rapid one-step antigen-immobilized inhibition ELISA for microcystin-LR is described. For microplate coating a microcystin-biotin conjugate was synthesized. Using the commercially available monoclonal antibody MC10E7 in our newly established assay, IC50 values of 0.045 μg l−1 have been achieved. The detection limit for microcystin-LR was 4 ng l−1. Considering the guidelines proposed by the world health organization (WHO) for microcystin-LR in drinking water (1 μg l−1) the sensitivity of our test is more than sufficient. The period of assay processing could successfully be shortened to about 3 h without any loss in sensitivity. The suitability of the newly developed assay was evaluated with microcystin-LR spiked environmental water samples. Recovery rates for microcystin-LR between 60 and 165% were obtained in the linear range of the test format. The antigen-immobilized test format provides a highly reproducible, easy, and fast to perform detection system for microcystin allowing an internal retrospective quality control of the assay. 相似文献
11.
Biosensor immunoassays for the detection of bisphenol A 总被引:1,自引:0,他引:1
Bisphenol A (BPA) is a xenoestrogen found in the environment, in consequence, for the biosensor detection of BPA we raised antibodies (polyclonal (PAbs) and monoclonal (MAbs)) against a structural analogue of BPA, 4,4 bis-(4-hydroxyphenyl) valeric acid (BVA). The kinetics of the MAb-BPA interaction were evaluated and the MAb providing the highest affinity was directly immobilized onto the sensor chip surface to evaluate a direct assay. Afterwards, the performance of the MAbs and the PAbs was compared in an inhibition assay using a BVA-coated chip.The highest sensitivity (limit of detection (LOD) of 0.4 μg L−1) was obtained with MAb 12 in the direct assay. However, the inhibition assay was the most robust and the PAbs showed the highest sensitivity (LOD of 0.5-1 μg L−1). The antibodies were specific for BVA and BPA as only minor cross-reactivities were found toward structurally related compounds or other endocrine disruptors. In the inhibition assay (with a run time of 6 min), water samples spiked with BPA at different levels (0.5-50 μg L−1) resulted in recoveries varying between 68% and 121%. The sensitivity of the inhibition assay could be improved 40 times (LOD of 0.03 μg L−1 with the Mab 12-based assay) using solid phase extraction (SPE). 相似文献
12.
《Analytical letters》2012,45(13):2280-2286
Eight disposable stochastic dot sensors based on porphyrins and modified diamond or carbon pastes were employed for the assay of ascorbic acid in pharmaceutical, beverages, and biological samples. The advantage of using such sensors for the assay of ascorbic acid is the possibility of qualitative and quantitative assay of ascorbic acid in one run of the experiment. The covered linear concentration range for these sensors was between 10?14 and 10?5 mol/L with high sensitivities. The proposed dot sensors were used reliably (RSD < 1%) for the assay of ascorbic acid from different samples for more than 6 months, with a recovery higher than 92.00%. 相似文献
13.
《液相色谱法及相关技术杂志》2012,35(8):1523-1534
Abstract A specific HPLC assay has been developed for determination of the radioprotective drug WR 2721. The method is based on precolumn derivatization of plasma with fluorescamine, separation with a C-18 cartridge and detection by fluorescence. An external standard was used for calibration, and values were adjusted based upon recovery of added 14C-labeled WR 2721. WR 2721 had a retention time of about 13 minutes using a mobile phase of acetonitrile/water (22:78), 0.01 M in dibutylammonium phosphate, at a flow rate of 2 mL/min. Sensitivity of the assay was characterized to 2 μg/mL, and detector response was linear over the range of 2 to 1100 μg/mL. The assay requires 90 μL of plasma and has a total chromatography time of about 45 minutes. 2-(3-Aminopropylamino)ethanethiol (WR 1065) and bis- [2- (3-aminopropylamino)ethyl]disulfide (WR 33278), metabolites of the drug, and a variety of primary amines were shown not to interfere with the assay. Suitability of this assay for pharmacokinetic studies was demonstrated in preliminary experiments with a beagle dog. 相似文献
14.
Ratthaphol Charlermroj Michalina Oplatowska Oraprapai Gajanandana Orawan Himananto Irene R. Grant Nitsara Karoonuthaisiri Christopher T. Elliott 《Mikrochimica acta》2013,180(7-8):643-650
We have made a comparison of (a) different surface chemistries of SPR sensor chips (such as carboxymethylated dextran and carboxymethylated C1) and (b) of different assay formats (direct, sandwich and subtractive immunoassay) in order to improve the sensitivity of the determination of the model bacteria Acidovorax avenae subsp. citrulli (Aac). The use of the carboxymethylated sensor chip C1 resulted in a better sensitivity than that of carboxymethylated dextran CM5 in all the assay formats. The direct assay format, in turn, exhibits the best sensitivity. Thus, the combination of a carboxymethylated sensor chip C1 with the direct assay format resulted in the highest sensitivity for Aac, with a limit of detection of 1.6?×?106 CFU mL-1. This SPR immunosensor was applied to the detection of Aac in watermelon leaf extracts spiked with the bacteria, and the lower LOD is 2.2?×?107 CFU mL?1. Figure
Possible strategies to improve the surface plasmon resonance-based immmunodetection of bacterial cells Acidovorax avenae subsp. citrulli (Aac) was used as a model pathogen. Two different sensor surfaces (carboxymethylated dextran CM5 and carboxymethylated C1) were compared. Direct detection, sandwich system and subtractive assay were investigated. The combination of a C1 chip with the direct assay format resulted in the highest sensitivity for Aac, with a limit of detection of 1.6*106 CFU mL?1 相似文献
15.
A novel path for the preparation of electrodes for lithium-sulphur cells was developed using a very fast laser-printing setup for the direct and dry i.e., solvent-free transfer of electrode materials onto the current collectors. Model electrodes could be prepared at very small dimensions enabling these batteries to be used even in portable small devices. The initial specific charge was remarkably high at about 1300 A h kg?1 (relating to the active material content of the electrode) with a loss of specific charge of about 75% after about 400 cycles at 1C. In addition, the dry transfer technique has highly beneficial effects on the environmental sustainability and, therefore, supports the concept of the use of “green” power storage. 相似文献
16.
《Journal of membrane science》1998,142(2):235-243
The composite tubular membranes were prepared by applying suspensions of zirconia particles to form separation top-layers on two different porous α-alumina supports and heating the coated supports to partly sinter the particles of top-layers. The conditions of synthesizing the ZrO2/α-Al2O3 membranes were investigated systematically. The mean pore diameter of zirconia membrane was about 0.2 μm by gas bubble pressure method, and the pure water flux was about 400 and 1500 l/(m2 h bar) for ZrO2 membrane on symmetric and asymmetric Al2O3 support, respectively. Zirconia membrane and three different alumina membranes were applied to separate oil–water emulsion obtained from steelworks to evaluate the permeability and separation characteristics, the ZrO2/α-Al2O3 MF membrane in this work was the preferred membrane. 相似文献
17.
Use of citric acid as a chelating agent and fuel, ammonium nitrate as fuel, boric acid as flux material and silica as supports, CaWO4:Ln3+@SiO2 (Ln = Er and Tm) nanoparticles were synthesized via a combustion reaction at 800 °C. Characterization of the samples was performed by X-ray diffractometer (XRD), reflectance UV–Vis spectrophotometer, fluorescence spectrophotometer (PL) and transmission electron microscope (TEM). XRD patterns showed that tetragonal crystalline structure of scheelite and silica supports were formed, and that the formation of a silica support could enhance the luminescence intensity of CaWO4:Ln3+. The reflectance UV–Vis and PL spectra indicated the broad absorption band of WO4 2? groups about 240 nm, the WO4 2? wide excitation band with maximum at 240 nm, a broad emission band of WO4 2? with maximum about 420 nm, and characteristic emissions of Ln3+ ions. According to the TEM analysis, CaWO4:Er3+@SiO2 and CaWO4:Tm3+@SiO2 nanoparticles have almost the same morphology with average particle sizes about 50 nm. 相似文献
18.
A study of biospecific interactions between lectins and glycoproteins using a quartz crystal microbalance biosensor with dissipation monitoring (QCM-D) was reported. Four lectins were covalently immobilised on the thiol-modified gold electrode of the QCM chips in order to obtain sensing surfaces. The frequency shift served as analytical signal and the dissipation shift provided additional information about the viscoelastic properties of the glycoprotein-lectin complex formed on the surface of the QCM chip. The working conditions of the assay were optimised. The interaction between different lectins and glycoproteins was characterised by specific frequency shifts and each glycoprotein displayed its own unique lectin-binding pattern. This lectin pattern can serve as a finger print for the discrimination between various glycoproteins. The biosensor enabled quantitative determination of glycoproteins in the concentration range of 50 μg mL−1 to 1 mg mL−1 with good linearity and R.S.D. of less than 6.0%. An additional advantage of the proposed biosensor was the possibility to re-use the same lectin surfaces during a long period of time (2 month) without changes in analytical response. This was experimentally achieved by the application of a proper regeneration solution (10 mM glycine-HCl, pH 2.5). The lectin-based quartz crystal microbalance technique is suitable both for rapid screening and for quantitative assay of serum glycoproteins. 相似文献
19.
Jarkko Rapala Kirsti ErkomaaJaana Kukkonen Kaarina SivonenKirsti Lahti 《Analytica chimica acta》2002,466(2):213-231
A colorimetric protein phosphatase inhibition assay (PPI assay), a commercial enzyme-linked immunosorbent assay (ELISA) test and different HPLC methods using UV detection were compared for the detection of cyanobacterial hepatotoxins, microcystins (MCYST) and nodularin. The suitability of the methods to detect different toxin variants was evaluated by using pure toxins and laboratory cultures as well as water and bloom samples of toxic cyanobacteria. The emphasis of the study was on the analysis of polar demethyl microcystin variants that are common in nature but for which there exist no commercial standards. The IC50 values of MCYST-LR for the PPI assay and the ELISA test were 2.2-2.5 and 0.26-0.38 μg l−1, respectively. The most important factors that decreased toxin recovery in sample treatment were the use of C18 cartridges and polypropylene containers. Good recoveries of toxins were obtained by using hydrophilic-lipophilic balanced (Oasis HLB, Waters) cartridges for concentrating the samples. The results obtained with the PPI assay, the ELISA test and HPLC correlated quantitatively well with the exception of [d-Asp3] microcystins. Concentrations of [d-Asp3]MCYST-RR measured with the PPI assay were only 5% of those obtained by the ELISA test and HPLC. Concentrations of hydrophobic microcystin variants were lower when analysed with ELISA than with the other methods. The World Health Organisation (WHO) has set a guideline value of 1 μg l−1 for the world-wide most common microcystin variant, MCYST-LR in drinking water. Since the quantitative ranges of the PPI assay and the ELISA test are within microcystin concentrations in natural waters, and both tests are easy to perform, they show potential for routine use in the screening and monitoring of microcystins from drinking water supplies and from recreational waters. 相似文献
20.
《Analytical letters》2012,45(11-12):2613-2626
Abstract A solid supported liquid membrane for the selective removal of Au(III) from chloride solutions has been developed by using Triisobutiphosphine sulfide (Cyanex 471x) In cumene as organic carrier. The membrane system is shown to be effective between chloride solutions ([Cl?]= 1.0 M) containing traces of Au(III) and SCN? 0.1 M solutions. Different kinds of at membrane supports have been studied. The results, expressed in terms of membrane permeability, show significant differences between the different supports employed, the polypropylene supports, being the most efficient. 相似文献