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1.
A new chemiluminescence (CL) method combined with flow injection technique is described for the determination of Cr(III) and
total Cr. It is found that a strong CL signal is generated from the reaction of Cr(III), lucigenin and KIO4 in alkaline condition. The determination of total Cr is performed by pre-reduction of Cr(VI) to Cr(III) by using H2SO3. The CL intensity is linearly related to the concentration of Cr in the range 4.0 × 10−10–1.0 × 10−6 g mL−1. The detection limit (3s
b) is 1 × 10−10 g mL−1 Cr and the relative standard deviation is 1.9% (5.0 × 10−8 g mL−1 of Cr(III) solution, n = 11). The method was applied to the determination of Cr(III) and total Cr in water samples and compared satisfactorily with
the official method. 相似文献
2.
A novel molecularly imprinted polymer solid-phase extraction (MISPE) with flow-injection chemiluminescence (CL) was developed
for the determination of pazufloxacin mesilate (PZFX). The molecularly imprinted polymer (MIP) was synthesized by using PZFX
as the imprinting molecule. A glass tube packed the particles of the MIP was employed as MISPE micro-column, which was connected
into the sampling loop of the eight-way injection valve for on-line selective preconcentration and extraction of PZFX. The
eluent of acetonitrile:acetic acid (9:1, v:v) was used as carrier for eluting the adsorbed PZFX to react with the mixture
of cerium(IV) and sodium sulfite in the flow cell to produce strong CL. The relative intensity of CL was linear to PZFX concentration
in the range from 2.5 × 10−9 to 2.5 × 10−7 g mL−1. The limit of detection was 7 × 10−10 g mL−1 (3 σ) and the relative standard deviation for 5 × 10−8 g mL−1of PZFX solution was 3.7% (n = 7). This method has been applied to the determination of PZFX in human urine. 相似文献
3.
Andreas Rahm Evgeni M. Kaidashev Heidemarie Schmidt Mariana Diaconu Andreas Pöppl Rolf Böttcher Christoph Meinecke Tilman Butz Michael Lorenz Marius Grundmann 《Mikrochimica acta》2006,153(1-2):21-25
A flow injection chemiluminescence method is proposed for the determination of cobalt, based on the strong catalytic effect
of Cobalt(II) (1,10-phenanthroline)3 complex on the lucigenin-periodate reaction in alkaline medium. Under the optimum experimental conditions, the chemiluminescence
signal responded linearly to the concentration of cobalt(II) in the 1.0 × 10−9–3.0 × 10−7 g mL−1 range with a detection limit of 4.4 × 10−10 g mL−1 cobalt(II). The relative standard deviation for the determination of 5.0 × 10−8 g mL−1 of cobalt was 2.3% in eleven replicated measurements. The method was successfully applied to the determination of cobalt(II)
in pharmaceutical preparations. 相似文献
4.
A chemiluminescence (CL) micro-flow system is presented for rapid determination of chemical oxygen demand (COD) in water at
room temperature. In this system, potassium dichromate is reduced to Cr3+ in 2 mol L−1 H2SO4 during the chemical oxidation of COD substances in the sample, and Cr3+ can be measured with the help of the luminol-H2O2 CL system. The polymethyl methacrylate micro-flow chip with discrete microdroplet sampling was used here. Effects on COD
determination (such as pH, concentrations, the channel length, and interference) were investigated. The linear range for COD
determination was 0.27–10 g L−1, and the detection limit was 100 mg L−1. The method was successfully applied to the determination of COD in wastewater samples. The data obtained with the present
method were in fairly good agreement with those obtained by the titrimetric method.
Correspondence: Zhujun Zhang, Key Laboratory of Analytical Chemistry for Life Science of Shaanxi Province, School of Chemistry
and Materials Science, Shaanxi Normal University, Xi’an 710062, P.R. China; Department of Chemistry, Institute of Analytical
Science, Southwest University, Beibei, Chongqing 400715, P.R. China 相似文献
5.
Obuchowska A 《Analytical and bioanalytical chemistry》2008,390(5):1361-1371
A new electrochemical method for the quantitation of bacteria that is rapid, inexpensive, and amenable to miniaturization
is reported. Cyclic voltammetry was used to quantitate M. luteus, C. sporogenes, and E. coli JM105 in exponential and stationary phases, following exposure of screen-printed carbon working electrodes (SPCEs) to lysed
culture samples. Ferricyanide was used as a probe. The detection limits (3s) were calculated and the dynamic ranges for E. coli (exponential and stationary phases), M. luteus (exponential and stationary phases), and C. sporogenes (exponential phase) lysed by lysozyme were 3 × 104 to 5 × 106 colony-forming units (CFU) mL−1, 5 × 106 to 2 × 108 CFU mL−1 and 3 × 103 to 3 × 105 CFU mL−1, respectively. Good overlap was obtained between the calibration curves when the electrochemical signal was plotted against
the dry bacterial weight, or between the protein concentration in the bacterial lysate. In contrast, unlysed bacteria did
not change the electrochemical signal of ferricyanide. The results indicate that the reduction of the electrochemical signal
in the presence of the lysate is mainly due to the fouling of the electrode by proteins. Similar results were obtained with
carbon-paste electrodes although detection limits were better with SPCEs. The method described herein was applied to quantitation
of bacteria in a cooling tower water sample.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
6.
Abdel-Aziz Youssef El-Sayed Ebtesam Ahmad Saad Basheer Mohamed Mohamed Ibrahime Mohamed Tarek Mohamed Zaki 《Mikrochimica acta》2000,135(1-2):19-27
Simple, rapid, sensitive and selective methods for the determination of Cr(III) and W(VI) with flavonol derivatives in the
presence of surface-active agents are proposed. In the pH ranges 3.4–4.2 and 1.9–2.5, the molar absorptivities of Cr(III)-morin-emulsifier
S (EFA) and W(VI)-morin-polyvinylpyrrolidone (PVP) systems are 1.13×105 and 2.13×104 L mol−1 cm−1 at 435 and 415 nm, respectively. The Cr(III)-quercetin-PVP and W(VI)-quercetin-cetylpyridinium bromide (CPB) systems are
formed in the pH ranges 4–4.6 and 2.2–2.8 with molar absorptivities 1.02×105 and 9.02×104 L. mol−1 cm−1 at 441 and 419 nm, respectively. The linear dynamic ranges for the determination of Cr(III) and W(VI) with morin in the presence
of EFA and PVP are 0.03–0.46 and 0.71–8.1 μg mL−1, respectively. The corresponding ranges with quercetin are 0.04–0.54 and 0.14–2.1 μg mL−1 of Cr(III) and W(VI), respectively. The r.s.d (n = 10) for the determination of 0.25 and 3.7 μg mL−1 of Cr(III) and W(VI) with morin and their detection limits are 0.88 and 0.99% and 0.016 and 0.63 μg mL−1, respectively. Using quercetin, the r.s.d (n = 10) for 0.22 and 1.2 μg mL−1 of Cr(III) and W(VI) and their detection limits are 0.92 and 0.91% and 0.015 and 0.08 μg mL−1, respectively. The critical evaluation of the proposed methods is performed by statistical analysis of the experimental data.
The proposed methods are applied to determine Cr in steel, non-ferrous alloys, wastewater and mud filtrate and to the determination
of W in steel.
Received March 8, 1999. Revision January 21, 2000. 相似文献
7.
This work reported for the first time the use of flow injection electrochemiluminescence (FI-ECL) sensor for the determination
of durabolin in an aqueous system based on CdTe quantum dot (QD) films. Aqueous CdTe colloidal solutions were prepared using
thioglycolic acid as a capping agent. Zetasizer Nano ZS (Malvern, UK) was employed to characterize the size of CdTe QDs. The
UV–vis and photoluminescence spectra of samples were systematically characterized. Indium tin oxide (ITO) slide glass was
modified with CdTe QDs by layer-by-layer self-assembly. CdTe QD films were packed into a homemade cell and used as a recognizer
of the FI-ECL sensor to determine durabolin. The intensive anodic ECL emission was obtained at a starting potential of +1.3 V
(vs. Ag/AgCl) in a carbonate bicarbonate buffer solution with a pH of 9.93 at an ITO electrode. The ECL intensity was correlated
linearly with the concentration of durabolin over the range of 1.0 × 10−8–1.0 × 10−5 g mL−1, and the detection limit was 2.5 × 10−9 g mL−1. The relative standard deviation for the determination of 1.0 × 10−6 g mL−1 durabolin was 1.04% (n = 11). This simple and sensitive sensor revealed good reproducibility for ECL analysis. As a result, the new FI-ECL sensor
had been successfully applied to the determination of durabolin in food samples. This strategy could be easily realized and
opened new avenues for the applications of QDs in ECL biosensing. 相似文献
8.
Leveriza F. Arenas Benilda S. Ebarvia Fortunato B. Sevilla III 《Analytical and bioanalytical chemistry》2010,397(7):3155-3158
A piezoelectric quartz crystal (PQC) sensor based on a molecularly imprinted polymer (MIP) has been developed for enantioselective
and quantitative analysis of d-(+)-methamphetamine (d(+)-MA). The sensor was produced by bulk polymerization and the resulting MIP was then coated on the
gold electrode of an AT-cut quartz crystal. Conditions such as volume of polymer coating, curing time, type of PQC, baseline
solvent, pH, and buffer type were found to affect the sensor response and were therefore optimized. The PQC-MIP gave a stable
response to different concentrations of d(+)-MA standard solutions (response time = 10 to 100 s) with good repeatability (RSD = 0.03
to 3.09%; n = 3), good reproducibility (RSD = 3.55%; n = 5), and good reversibility (RSD = 0.36%; n = 3). The linear range of the sensor covered five orders of magnitude of analyte concentration, ranging from 10−5 to 10−1 μg mL−1, and the limit of detection was calculated as 11.9 pg d(+)-MA mL−1
. The sensor had a highly enantioselective response to d(+)-MA compared with its response to l(−)-MA, racemic MA, and phentermine.
The developed sensor was validated by applying it to human urine samples from drug-free individuals spiked with standard d(+)-MA
and from a confirmed MA user. Use of the standard addition method (SAM) and samples spiked with d(+)-MA at levels ranging
from 1 × 10−3 to 1 × 10−2 μg mL−1 showed recovery was good (95.3 to 110.9%). 相似文献
9.
The electrochemical behavior of the ofloxacin–copper complex, Cu(II)L2, at a mercury electrode, and the interaction of DNA with the complex have been investigated. The experiments indicate that
the electrode reaction of Cu(II)L2 is an irreversible surface electrochemical reaction and that the reactant is of adsorbed character. In the presence of DNA,
the formation of the electrochemically non-active complexes Cu(II)L2-DNA, results in the decrease of the peak current of Cu(II)L2. Based on the electrochemical behavior of the Cu(II)L2 with DNA, binding by electrostatic interaction is suggested and a new method for determining nucleic acid is proposed. Under
the optimum conditions, the decrease of the peak current is in proportional to the concentration of nucleic acids in the range
from 3 × 10−8 to 3 × 10−6 g · mL−1 for calf thymus DNA, from 1.6 × 10−8 to 9.0 × 10−7 g · mL−1 for fish sperm DNA, and from 3.3 × 10−8 to 5.5 × 10−7 g · mL−1 for yeast RNA. The detection limits are 3.3 × 10−9, 6.7 × 10−9 and 8.0 × 10−9 g · mL−1, respectively. The method exhibits good recovery and high sensitivity in synthetic samples and in real samples. 相似文献
10.
S. Schumacher R. Wüstneck B.-R. Paulke R. Cartier U. Pison 《Colloid and polymer science》2009,287(2):203-214
The binding of Gd3+ to two carboxylated polyglycidyl methacrylate latices was investigated. The latices differed in size (60 and 140 nm for CL6
and CL3, respectively) and surface charge density. The Gd3+ concentration in aqueous suspension was determined using an arsenazo (III) assay. Using 153Gd3+, the bound amount was determined directly. Because of the high binding affinity, ligand depletion became evident. The binding
was pH dependent, investigated in buffer solutions not influencing the arsenazo (III) assay. Optimal binding occurs by formation
of sodium salts of the carboxylic groups and replacement of Na+ and H+ by Gd3+. The dissociation constants of the particles were k
D ≈ 5 × 10−5 mol/L (CL3) and 10−4 mol/L (CL6), without cooperativity (Hill plot). Colloidal stability was investigated.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
11.
A fast and sensitive liquid chromatography–mass spectrometry method was developed for the determination of ursolic acid (UA)
in rat plasma and tissues. Glycyrrhetinic acid was used as the internal standard (IS). Chromatographic separation was performed
on a 3.5 μm Zorbax SB-C18 column (30 mm × 2.1 mm) with a mobile phase consisting of methanol and aqueous 10 mM ammonium acetate
using gradient elution. Quantification was performed by selected ion monitoring with (m/z)− 455 for UA and (m/z)− 469 for the IS. The method was validated in the concentration range of 2.5 − 1470 ng mL−1 for plasma samples and 20 − 11760 ng g−1 for tissue homogenates. The intra- and inter-day assay of precision in plasma and tissues ranged from 1.6% to 7.1% and 3.7%
to 9.0%, respectively, and the intra- and inter-day assay accuracy was 84.2 − 106.9% and 82.1 − 108.1%, respectively. Recoveries
in plasma and tissues ranged from 83.2% to 106.2%. The limits of detections were 0.5 ng mL−1 or 4.0 ng g−1. The recoveries for all samples were >90%, except for liver, which indicated that ursolic acid may metabolize in liver. The
main pharmacokinetic parameters obtained were T
max = 0.42 ± 0.11 h, C
max = 1.10 ± 0.31 μg mL−1, AUC = 1.45 ± 0.21 μg h mL−1 and K
a = 5.64 ± 1.89 h−1. The concentrations of UA in rat lung, spleen, liver, heart, and cerebellum were studied for the first time. This method
is validated and could be applicable to the investigation of the pharmacokinetics and tissue distribution of UA in rats. 相似文献
12.
2,5-Dimercapto-1,3,4-thiadiazole (DMTD) self-assembled monolayer on gold electrode was prepared and investigated by electrochemical
measurement. The DMTD/Au electrode exhibited a significantly increased sensitivity and selectivity for Pb(II) in acetate buffer
(pH 5.5) at a potential of −1.0 V (vs Ag/AgCl) for 4 min by anodic stripping voltammetry. The influence of various experimental
parameters on the voltammetric response was studied. Under the optimized working conditions, the dependence of the stripping
peak current response on concentration of Pb(II) was linear in the range of 1–45 μmol L−1 with a correlation coefficient of 0.9988, and the detection limit was 0.10 μmol L−1. The relative standard deviation of the results was 3.4% for six successive determinations of a 20 μmol L−1 Pb(II) solution. A study of interfering substances was also performed. The method was applied to the determination of Pb(II)
in water samples with satisfactory results.
Correspondence: Hong Qun Luo, School of Chemistry and Chemical Engineering, Southwest University, 400715 Chongqing, China 相似文献
13.
A novel and simple chemiluminescence (CL) method has been developed and validated for determination of metformin. This method
is based on hydroxyl radical chemiluminescence—the hydroxyl radical generated by reaction of Cu(II) and hydrogen peroxide
oxidizes rhodamine B (RhB) to produce weak CL which can be enhanced by metformin. At the same time, metformin molecularly
imprinted polymer (MIP) was synthesized. After enrichment based on the selectivity of metformin-MIP, the CL method was successfully
applied to the determination of metformin in human serum. The linear range was from 1.0×10−8 to 1.0×10−6 g mL−1 and the detection limit was 4×10−9 g mL−1. The relative standard deviation at 2.0×10−7 g mL−1 by use of MIP was 3.67% (n=7). 相似文献
14.
A rapid flow-injection method with chemiluminescence (CL) detection is described for the determination of glutathione (GSH).
The method is based on the CL reaction of luminol and hydrogen peroxide. GSH can greatly enhance the chemiluminescence intensity
in 0.1 mol/L borax–sodium hydroxide buffer solution (pH = 9.7). The maximum CL intensity was directly proportional to the
concentration of GSH in the range 3.0 × 10−7–2.0 × 10−5 mol/L, and the detection limit was 6.8 × 10−8 mol/L. The relative standard deviation was 3.4% for 5.0 × 10−6 mol/L of GSH (n = 11).
Received October 23, 2001; accepted June 18, 2002 相似文献
15.
Ahmad Soleymanpour Bahram Garaili S. Masoud Nabavizadeh 《Monatshefte für Chemie / Chemical Monthly》2008,139(12):1439-1445
Three platinum(II) complexes were synthesized and studied to characterize their ability as an anion carrier in a PVC membrane electrode. The polymeric membrane electrodes (PME) and also coated glassy carbon electrodes (CGCE) prepared with
one of these complexes showed excellent response characteristics to perchlorate ions. The electrodes exhibited Nernstian responses to ClO4
− ions over a wide concentration range from 1.5 × 10−6 to 2.7 × 10−1 M for PME and 5.0 × 10−7 to 1.9 × 10−1 M for CGCE with low detection limits (9.0 × 10−7 M for PME and 4.0 × 10−7 M for CGCE). The electrodes possess fast response time, satisfactory reproducibility, appropriate lifetime and, most importantly,
good selectivity toward ClO4
− relative to a variety of other common anions. The potentiometric response of the electrodes is independent of the pH of the test solution in the pH range 2.0–9.0. The proposed sensors were used in potentiometric determination of perchlorate ions in mineral water and urine
samples.
Correspondence: Ahmad Soleymanpour, Department of Chemistry, Damghan Basic Science University, Damghan, Iran. 相似文献
16.
Determination of the effective components in traditional Chinese medicine is one of the key steps for its identification.
In this paper a novel and sensitive chemiluminescence (CL) method for the determination of rhein coupled with flow-injection
analysis (FIA) is developed. It is based on the strong sensitizing effect on the weak CL reaction between luminol and ferricyanide
in alkaline solution. Under optimal experimental conditions, the relative CL intensity is proportional to the concentration
of rhein in the range of 7.0 × 10−12–7.0 × 10−10 mol L−1 and 1.0 × 10−9–4.0 × 10−5 mol L−1, the detection limit is 1.478 × 10−13 mol L−1, and the relative standard deviation (RSD) for 9 parallel measurements of 1.408 × 10−7 mol L−1 rhein is 3.4%. The method was successfully applied to the determination of rhein in pharmaceutical preparations. The possible
mechanism of CL is also briefly discussed. 相似文献
17.
Krzysztof Miecznikowski James A. Cox Adam Lewera Pawel J. Kulesza 《Journal of Solid State Electrochemistry》2000,4(4):199-204
We describe a sol-gel approach by which iron hexacyanoferrate is immobilized in silica in a manner suited to investigation
by electrochemistry in the absence of a contacting liquid phase. Such physicochemical parameters as concentration of redox
sites (C
o) and apparent (effective) diffusion coefficient (D
app) are estimated by performing cyclic voltammetric and potential step experiments in two time regimes, which are characterized
by linear and spherical diffusional patterns, respectively. Values of D
app and C
o thereby obtained are 2.0 × 10−6 cm2 s−1 and 1.4 × 10−2 mol dm−3. The D
app value is larger than expected for a typical solid redox-conducting material. Analogous measurements done in iron(III) hexacyanoferrate(III)
solutions of comparable concentrations, 1.0 × 10−2 and 5.0 × 10−3 mol dm−3, yield D
app on the level of 5–6 × 10−6 cm2 s−1. Thus, the dynamics of charge propagation in this sol-gel material is almost as high as in the liquid phase. The residual
water in the silica, along with the pore structure, are important to the overall mechanism of charge transport, which apparently
is limited by physical diffusion rather than electron self-exchange. Under conditions of a solid state voltammetric experiment
which utilizes an ultramicroelectrode, encapsulated iron hexacyanoferrate redox centers seem to be in the dispersed colloidal
state rather than in a form of the rigid polymeric film.
Received: 8 April 1999 / Accepted: 13 August 1999 相似文献
18.
Eduardo Marafon Lauro T. Kubota Yoshitaka Gushikem 《Journal of Solid State Electrochemistry》2009,13(3):377-383
SiO2/ZrO2/C carbon ceramic material with composition (in wt%) SiO2 = 50, ZrO2 = 20, and C = 30 was prepared by the sol–gel-processing method. A high-resolution transmission electron microscopy image
showed that ZrO2 and the graphite particles are well dispersed inside the matrix. The electrical conductivity obtained for the pressed disks
of the material was 18 S cm−1, indicating that C particles are also well interconnected inside the solid. An electrode modified with flavin adenine dinucleotide
(FAD) prepared by immersing the solid SiO2/ZrO2/C, molded as a pressed disk, inside a FAD solution (1.0 × 10−3 mol L−1) was used to investigate the electrocatalytic reduction of bromate and iodate. The reduction of both ions occurred at a peak
potential of −0.41 V vs. the saturated calomel reference electrode. The linear response range (lrr) and detection limit (dl)
were: BrO3
−, lrr = 4.98 × 10−5–1.23 × 10−3 mol L−1 and dl = 2.33 μmol L−1; IO3
−, lrr = 4.98 × 10−5 up to 2.42 × 10−3 and dl = 1.46 μmol L−1 for iodate. 相似文献
19.
Borges KB de Oliveira AR Barth T Jabor VA Pupo MT Bonato PS 《Analytical and bioanalytical chemistry》2011,399(2):915-925
The purpose of this study was the development and validation of an LC–MS–MS method for simultaneous analysis of ibuprofen
(IBP), 2-hydroxyibuprofen (2-OH-IBP) enantiomers, and carboxyibuprofen (COOH-IBP) stereoisomers in fungi culture medium, to
investigate the ability of some endophytic fungi to biotransform the chiral drug IBP into its metabolites. Resolution of IBP
and the stereoisomers of its main metabolites was achieved by use of a Chiralpak AS-H column (150 × 4.6 mm, 5 μm particle
size), column temperature 8 °C, and the mobile phase hexane–isopropanol–trifluoroacetic acid (95: 5: 0.1, v/v) at a flow rate of 1.2 mL min−1. Post-column infusion with 10 mmol L−1 ammonium acetate in methanol at a flow rate of 0.3 mL min−1 was performed to enhance MS detection (positive electrospray ionization). Liquid–liquid extraction was used for sample preparation
with hexane–ethyl acetate (1:1, v/v) as extraction solvent. Linearity was obtained in the range 0.1–20 μg mL−1 for IBP, 0.05–7.5 μg mL−1 for each 2-OH-IBP enantiomer, and 0.025–5.0 μg mL−1 for each COOH-IBP stereoisomer (r ≥ 0.99). The coefficients of variation and relative errors obtained in precision and accuracy studies (within-day and between-day)
were below 15%. The stability studies showed that the samples were stable (p > 0.05) during freeze and thaw cycles, short-term exposure to room temperature, storage at −20 °C, and biotransformation
conditions. Among the six fungi studied, only the strains Nigrospora sphaerica (SS67) and Chaetomium globosum (VR10) biotransformed IBP enantioselectively, with greater formation of the metabolite (+)-(S)-2-OH-IBP. Formation of the COOH-IBP stereoisomers, which involves hydroxylation at C3 and further oxidation to form the
carboxyl group, was not observed. 相似文献
20.
A simple, rapid and specific chemiluminescence (CL) method for the determination of glutathione has been developed. The method
is based on the enhanced CL of the reaction between Ru(phen)3
2+ (phen = 1,10-phenanthroline) and KMnO4 by glutathione in HCl medium. Under the optimum conditions, the response is linearly proportional to the concentration of
glutathione between 1.5 × 10−7 and 1.0 × 10−5 mol L−1. The dection limit for glutathione (5.8 × 10−8 mol L−1) is about 10 and 200 times better than those of the spectrophotometric method using Ellman regent and the Lucigenin – CL
method, respectively. The final procedure allows the determination of glutathione in human serum with recoveries of 92%–108%.
A satisfactory agreement was obtained with a mean relative difference of 2.5% compared to the HPLC method. 相似文献