共查询到20条相似文献,搜索用时 15 毫秒
1.
Two novel N-(2-mercapto-1,3,4-thiadiazol-5-yl)-N′-(4-substituted-arylacetyl) urea compounds have been synthesized, characterized by NMR and MS, and used as self-assembly reagents
to form self-assembled monolayers (SAMs) on Pt electrodes. The modified electrodes were characterized by electrochemical methods.
The electrochemical behavior of p-benzenediol at the SAMs electrodes was investigated. It was found that the electrochemical response to p-benzenediol is controlled by diffusion and can be electrocatalyzed to obtain more symmetrical redox peaks and higher voltammetric
current response at the SAMs electrodes, with a peak separation of 80 mV. For p-benzenediol the process at the SAMs electrodes is quasi-reversible with a rate constant of 0.6742 s−1. The SAMs electrodes have been used to determine p-benzenediol by differential pulse voltammetry. The peak current was linear for concentrations of p-benzenediol in the range 1×10−7−5×10−4 mol L−1 and the detection limit was 4.0×10−8 mol L−1. The SAMs electrodes were used to determine p-benzenediol in real photographic developer and in a synthetic waste water sample; the standard addition recovery was in the
range 96.6–100.4%.
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2.
A new post-chemiluminescence (PCL) phenomenon was observed when phenothiazine medications were injected into the reaction
mixture after the chemiluminescence (CL) reaction of luminol and potassium ferricyanide had finished. A possible reaction
mechanism was proposed based on studies of the kinetic characteristics of the CL, CL spectra, fluorescence spectra, and on
other experiments. The feasibility of determining various phenothiazine medications by utilizing these PCL reactions was examined.
A molecular imprinting–post-chemiluminescence (MI-PCL) method was established for the determination of chlorpromazine hydrochloride
using a chlorpromazine hydrochloride-imprinted polymer (MIP) as the recognition material. The method displayed high selectivity
and high sensitivity. The linear range of the method was 1.0×10−8∼1.0×10−6, with a linear correlation coefficient of 0.9985. The detection limit was 3×10−9 g/ml chlorpromazine hydrochloride, and the relative standard deviation for a 1.0×10−7 g/ml chlorpromazine hydrochloride solution was 4.0% (n=11). The method has been applied to the determination of chlorpromazine hydrochloride in urine and animal drinking water
with satisfactory results.
相似文献
3.
Arvand M Pourhabib A Shemshadi R Giahi M 《Analytical and bioanalytical chemistry》2007,387(3):1033-1039
Liquid polymer membrane electrodes based on nickel and manganese phthalocyanines were examined for use as anion-selective
electrodes. The electrodes were prepared by incorporating the ionophores into plasticized poly(vinyl chloride) membranes,
which were directly coated onto the surfaces of graphite electrodes. The resulting electrodes demonstrate near-Nernstian responses
over a wide linear range of perchlorate anion (5 × 10−7 to 1 × 10−1 M). The electrodes have a fast response time, submicromolar detection limits (5 × 10−7 M perchlorate), and could be used over a wide pH range of 3.5–10. The influences of lipophilic cationic and anionic additives
on the response properties of the electrodes were investigated. The proposed sensors revealed high selectivity for perchlorate
over a number of common inorganic and organic anions. The highest selectivity was observed for the electrode based on manganese
phthalocyanine in the presence of the lipophilic anionic additive sodium tetrakis[3,5-bis(trifluoromethyl)phenyl]borate. Application
of the electrodes to determine perchlorate in tap water and human urine is also reported.
相似文献
4.
Garrigosa AM Ariño C Díaz-Cruz JM Esteban M 《Analytical and bioanalytical chemistry》2008,390(2):769-776
The possibilities of anodic stripping voltammetry (ASV) using an alternating current (AC) scan in the stripping step have
been checked through the study of the complexation of cadmium by Suwannee river fulvic acid (SRFA), a reference fulvic acid
from the International Humic Substances Society. Because of the strong electrode adsorption of SRFA, AC mode appears to be
a good approach to the study when proper selection of the phase angle is made. The goodness of AC mode in ASV has been demonstrated,
and the complexation constant of 3.71 ± 0.04 determined is in good agreement with the value of the constant obtained by the
reference technique of reverse pulse polarography. Some particularities of SRFA have been observed, among them its homofunctional
and strongly heterogeneous behaviour in cadmium complexation and the impossibility of avoiding electrode adsorption problems
in ASV measurements at very low metal concentrations.
Figure DP anodic stripping and AC anodic stripping voltammograms at −12° and −65° during the titration of a 10−7 mol L−1 Cd(II) solution with SRFA at pH 7.5 in 0.05 L−1 Tris
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
5.
The damped glycolytic oscillation phenomenon occurring in starved cells of the yeast Saccharomyces cerevisiae (NBRC 0565) was characterization for application to a toxicity bioassay. S. cerevisiae was grown under semi-anaerobic conditions. The transient oscillations were observed photometrically as the time course of
the fluorescent intensity of reduced pyridine nucleotide resulting from instantaneous addition of glucose to a cell suspension.
In this study, simple and reproducible conditions inducing damped oscillations were obtained by modifying a literature method.
For estimation of the wave shapes of the damped oscillations we used six indexes. To investigate the total reproducibility
as the averaged relative standard deviation (RSDav) for the six indexes obtained from the wave shapes, the damped oscillations were induced under the optimum conditions and
the RSDav values were calculated as 14% in a buffer cell suspension (n = 62) and 22% in a water cell suspension (n = 78). Finally, the effects of glucose concentration on the six indexes were examined, and all the indexes changed when the
glucose concentration was changed. Excellent correlations were obtained between the index of oscillation-state time and the
concentration of glucose in a buffer cell suspension (r = 0.9985, 0.5–250 mmol L−1, 10 points) and in a water cell suspension (r = 0.9989, 2.5 μmol L−1–250 mmol L−1, 12 points), respectively.
Figure Characterization of damped glycolytic oscillation, (a) typical shape, and (b) its estimation
Electronic supplementary material The online version of this article (doi:)contains supplementary material, which is available to authorized users. 相似文献
6.
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%.
相似文献
7.
Determining sulfamonomethoxine and its acetyl/hydroxyl metabolites in chicken plasma under organic solvent-free conditions 总被引:1,自引:0,他引:1
Furusawa N 《Analytical and bioanalytical chemistry》2006,385(8):1570-1574
A quantitative technique is described for a sample preparation followed by high performance liquid chromatography method for
the simultaneous determination of sulfamonomethoxine and its metabolites, N
4-acetyl SMM and 2,6-dihydroxy SMM, in chicken plasma. The average recoveries, analytical total time, and limits of quantitation
were ≥80% (relative standard deviations (SD) ≤6%), <30 min sample-1 (12 samples in 2 h), and ≤0.09 μg ml−1, respectively. The procedure, performed under 100% aqueous conditions, uses no organic solvents and toxic reagents at all
and is, therefore, harmless to the environment and humans.
相似文献
8.
A supramolecular catalytic kinetic spectrofluorimetric method was developed for the determination of platinum(IV) and the
possible mechanism of catalytic reaction was discussed. The method was based on the fluorescence-enhancing reaction of salicylaldehyde
furfuralhydrazone (SAFH) with potassium bromate, which was catalysed by platinum(IV) in a water–ethanol medium. β–Cyclodextrin (β-CD) obviously sensitized the determination at pH 5.20 and 25°C. Under optimum conditions, the β-CD–platinum–KBrO3–SAFH supramolecular kinetic catalytic reaction system had excitation and emission maxima at 372 and 461 nm, respectively.
The linear range of this method was 0.60–180 ng ml−1 with a relative standard deviation of 1.2%, and the detection limit was 0.18 ng ml−1. Investigation of the mechanism and the effects of interferences is presented. The proposed method was applied successfully
to determine trace platinum(IV) in the chemotherapeutic drug cisplatin and serum from patients with satisfactory results.
相似文献
9.
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
10.
Patricia W. Stege Lorena L. Sombra Germán A. Messina Luis D. Martinez María F. Silva 《Analytical and bioanalytical chemistry》2009,394(2):567-573
Many aromatic compounds can be found in the environment as a result of anthropogenic activities and some of them are highly
toxic. The need to determine low concentrations of pollutants requires analytical methods with high sensitivity, selectivity,
and resolution for application to soil, sediment, water, and other environmental samples. Complex sample preparation involving
analyte isolation and enrichment is generally necessary before the final analysis. The present paper outlines a novel, simple,
low-cost, and environmentally friendly method for the simultaneous determination of p-nitrophenol (PNP), p-aminophenol (PAP), and hydroquinone (HQ) by micellar electrokinetic capillary chromatography after preconcentration by cloud
point extraction. Enrichment factors of 180 to 200 were achieved. The limits of detection of the analytes for the preconcentration
of 50-ml sample volume were 0.10 μg L−1 for PNP, 0.20 μg L−1 for PAP, and 0.16 μg L−1 for HQ. The optimized procedure was applied to the determination of phenolic pollutants in natural waters from San Luis,
Argentina.
Figure Schematic representation of the cloud point extraction process. 相似文献
11.
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
12.
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.
相似文献
13.
Feng QZ Zhao LX Yan W Ji F Wei YL Lin JM 《Analytical and bioanalytical chemistry》2008,391(3):1073-1079
Highly sensitive flow-injection chemiluminescence (CL) combined with molecularly imprinted solid-phase extraction (MISPE)
has been used for determination of 2,4-dichlorophenol (2,4-DCP) in water samples. The molecularly imprinted polymer (MIP)
for 2,4-DCP was prepared by non-covalent molecular imprinting methods, using 4-vinylpyridine (4-VP) and ethylene glycol dimethacrylate
(EGDMA) as the monomer and cross-linker, respectively. 2,4-DCP could be selectively adsorbed by the MIP and the adsorbed 2,4-DCP
was determined by its enhancing effect on the weak chemiluminescence reaction between potassium permanganate and luminol.
The enhanced CL intensity was linear in the range from 1 × 10−7 to 2 × 10−5g mL−1. The LOD (S/N = 3) was 1.8 × 10−8g mL−1, and the relative standard deviation (RSD) was 3.0% (n = 11) for 1.4 × 10−6g mL−1. The proposed method had been successfully applied to the determination of 2,4-DCP in river water.
Figure Effect of 4-VP content on the ultraviolet spectrum of 2,4-DCP in chloroform 相似文献
14.
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
15.
Martínez-Cabot A Varela B Lloveras M Campos R Marco MP Messeguer A 《Analytical and bioanalytical chemistry》2008,391(2):617-624
The fatty acid esters of 3-(N-phenylamino)propane-1,2-diol (PAP) are biomarkers of toxic oil batches that caused toxic oil syndrome (TOS), an intoxication
that caused over 400 deaths and affected 20,000 people in Spain in 1981. PAP esters are converted into PAP by human pancreatic
lipase. The in vivo biotransformation of PAP in two mouse strains generated potentially toxic metabolites. Here we report
an enzyme-linked immunosorbent assay (ELISA) for PAP detection incorporating antibodies generated using PAP-hapten derivatives
1 and 2. The immunizing haptens were designed to recognize the phenylamino and hydroxymethylene moieties of the PAP structure. The
antisera raised against 1-HCH showed greater affinity for free PAP, as demonstrated in competitive experiments using either 1-BSA or 2-BSA as coating antigens. The developed ELISA detects PAP at a threshold of 130 μg L−1 and can be used over a wide range of pH and ionic strength values. The assay can be applied to human urine samples, after
a simple treatment method, with good recovery according to the correlation obtained when analyzing blind spiked urine samples.
Figure Development of an ELISA for PAP in human urine 相似文献
16.
A novel electrochemical sensor for methyl parathion based on silicate– cetyltrimethylammonium bromide nanocomposite film has
been fabricated by electro-assisted deposition onto glassy carbon electrode in one-step via an electrochemical modulation
of pH at the electrode/solution interface to promote controlled gelification of tetraethylorthosilicate sol, and was characterized
with scanning electron microscopy, X-ray diffraction, and electrochemical impedance spectroscopy. The electrochemical sensing
of methyl parathion on the film-modified electrode was investigated applying cyclic voltammetry and square wave voltammetry.
Compared to the unmodified electrode, the shapes of the redox peaks were improved and the peak currents significantly increased.
Experimental parameters such as deposition time, pH value, and accumulation conditions have been optimized. A linear relationship
between the peak current and methyl parathion concentration was obtained in the range from 1.0 × 10−7 to 1.0 × 10−4 mol L−1 with a detection limit of 1.04 × 10 −8 mol L−1 (S/N = 3) after accumulation at 0 V for 120 s. The film electrode shows great promise for determination of methyl parathion in
real samples.
相似文献
17.
Schütz K Persike M Carle R Schieber A 《Analytical and bioanalytical chemistry》2006,384(7-8):1511-1517
The anthocyanin pattern of artichoke heads (Cynara scolymus L.) has been investigated by high-performance liquid chromatography–electrospray ionization mass spectrometry. For this purpose a suitable extraction and liquid chromatographic method was developed. Besides the main anthocyanins—cyanidin 3,5-diglucoside, cyanidin 3-glucoside, cyanidin 3,5-malonyldiglucoside, cyanidin 3-(3′′-malonyl)glucoside, and cyanidin 3-(6′′-malonyl)glucoside—several minor compounds were identified. Among these, two peonidin derivatives and one delphinidin derivative were characterized on the basis of their fragmentation patterns. To the best of our knowledge this is the first report on anthocyanins in artichoke heads consisting of aglycones other than those of cyanidin. Quantification of individual compounds was performed by external calibration. Cyanidin 3-(6′′-malonyl)glucoside was found to be the major anthocyanin in all the samples analyzed. Total anthocyanin content ranged from 8.4 to 1,705.4 mg kg−1 dry mass.
相似文献
18.
A new flow injection chemiluminescent immunoassay was developed for the detection of 17β-estradiol (E2). The method uses p–iodophenol (PIP) as enhancer and is based on a solid-phase immunoassay format in which an E2–OVA immobilized immunoaffinity column inserted in the flow system is used to trap unbound horseradish peroxidase (HRP)-labeled
anti-E2 antibody after an off-line incubation of E2 with HRP-labeled anti-E2 antibody. The trapped enzyme conjugate was detected by injecting substrates to produce an enhanced chemiluminescence (CL)
response. The linear range for E2 was 10.0–1,000.0 ng mL−1 with a correlation coefficient of 0.996 and a detection limit of 3.0 ng mL−1. The sampling and chemiluminescence detection time for one sample was 400 s after a pre-incubation procedure of 30 min. Serum
samples detected by this method were in good agreement with the results obtained by EIA with E2–biotin.
相似文献
19.
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
20.
Garrigosa AM Ariño C Díaz-Cruz JM Esteban M 《Analytical and bioanalytical chemistry》2008,391(6):2209-2218
A comparison of a differential pulse polarographic with a phase sensitive alternating current polarographic study of the Cd-Cys-Gly
and Cd-PC2 systems [PC2 being a phytochelatin of general structure (γ-Glu-Cys)
n
-Gly, with n = 2] has been performed. The chemometric multivariate curve resolution method with alternating least squares was applied
in the experimental data analysis. The results obtained by both polarographic techniques have made it possible to find out
the formation sequences of the complexes and their final stoichiometries. The alternating current polarograms compared with
the differential pulse ones show some differences (a new signal and an important shift of peak potentials), which anyway are
consistent with some of the conclusions obtained by differential pulse polarography. This fact implies that although the alternating
current polarography results need some corrections before data treatment, they provide extra information that complements
the conclusions achieved by differential pulse polarography.
Figure Voltammograms at ACP(−10°), ACP(−65°) and corrected ACP during the titration of a 10−5 mol L−1 Cd(II) solution with PC2 at pH 8.5 in 0.05 L−1 Tris. 相似文献