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1.
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
2.
A simple flow injection chemiluminescence (CL) method was developed for the determination of atenolol using Eu3+ as the probe. It was found that the weak CL generated by the KMnO4-Na2SO3 reaction can be significantly enhanced by the atenolol-Eu3+ complex. The experimental conditions were optimized. The CL intensity was linearly related to atenolol concentration in the
range from 8.0 × 10−9 to 1.0 × 10−5 g mL−1. The detection limit (3s
b) was 3 × 10−9 g mL−1 and the relative standard deviation for 1.0 × 10−7 g mL−1 atenolol solution was 2.4% (n = 11). The method has high sensitivity, wide linear range, inexpensive instrumentation, and has been applied to the determination
of atenolol in spiked human urine and plasma samples with recoveries within the range 95.5–104.0%.
Supplementary material to this paper is available in electronic form at
Electronic supplementary material: Discussion of the reaction mechanism and additional figures are available online as electronic
supplementary material (ESM) at .
Correspondence: Jianxiu Du, 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 相似文献
3.
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
4.
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
5.
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
6.
Ashraf A. Mohamed Saleh A. Ahmed Mohamed F. El-Shahat 《Monatshefte für Chemie / Chemical Monthly》2002,133(1):31-40
Summary. A highly selective, sensitive, and simple catalytic method for the determination of molybdenum in natural and waste waters
was developed. It is based on the catalytic effect of Mo(VI) on the oxidation of 2-aminophenol with H2O2. The reaction is monitored spectrophotometrically by tracing the oxidation product at 430 nm after 10 min of mixing the reagents.
Addition of 800 μg · cm−3
EDTA conferred high selectivity; however, interfering effects of Au(III), Cr(III), Cr(VI), and Fe(III) had to be eliminated by
a reduction and co-precipitation procedure with SnCl2 and Al(OH)3. Mo(VI) shows a linear calibration graph up to 11.0 ng · cm−3; the detection limit, based on the 3S
b-criterion, is 0.10 ng · cm−3. The unique selectivity and sensitivity of the new method allowed its direct application to the determination of Mo(VI) in
natural and waste waters.
Received April 11, 2001. Accepted (revised) June 18, 2001 相似文献
7.
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
8.
Grabarczyk M 《Analytical and bioanalytical chemistry》2008,390(3):979-986
A simple and fast catalytic adsorptive stripping voltammetric procedure for trace determination of Cr(VI) in natural samples
containing high concentrations of humic substances has been developed. The procedure for chromium determination in the presence
of DTPA and nitrates was employed as the initial method. In order to enhance the selectivity vs. Cr(III) the measurements
were performed at 40°C. Interference from dissolved organic matter such as humic and fulvic acids was drastically decreased
by adding Amberlite XAD-7 resin to the voltammetric cell before the deaeration step. The whole procedure was applied to a
single cell, which allowed monitoring of the voltammetric scan. Optimum conditions for removing humic and fulvic acids due
to their adsorption on XAD-7 resin were evaluated. The use of XAD-7 resin also minimize interferences from various cationic,
anionic, and nonionic surfactants. The calibration graph for Cr(VI) for an accumulation time of 30 s was linear in the range
5 × 10−10 to 5 × 10−8 mol L−1. The relative standard deviation for determination of Cr(VI) at a concentration of 1 × 10−8 mol L−1 was 3.5% (n = 5). The detection limit estimated from 3 times the standard deviation for low Cr(VI) concentrations and an accumulation
time of 30 s was about 1.3 × 10−10 mol L−1. The proposed method was successfully applied to Cr(VI) determination at trace levels in soil samples. 相似文献
9.
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
10.
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
11.
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
12.
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
13.
A selective, sensitive and simple catalytic method is developed for the determination of vanadium in natural and highly polluted
waste waters. The method is based on the catalytic effect of VV and/or VIV on the bromate oxidative-coupling reaction of metol with phloroglucinol (PG). The reaction is followed spectrophotometrically
by tracing the oxidation product at 464 nm after 10 minutes of mixing the reagents. The optimum reaction conditions are metol
(8.0×10−3 M), PG (4.0×10−3 M) and bromate (2×10−2 M) at 35°C and in presence of an activator-b uffer mixture of 5×10−2 M of each of citric and monochloroacetic acids (pH 2.40). Following the recommended procedure, vanadium can be determined
with a linear calibration graph up to 8.0 ng mL−1 and a detection limit, based on the 3sb criterion, of 0.1 ng mL−1. Spectrophotometric determination of as little as 1.0 ng mL−1 of VV or VIV in aqueous solutions gave an average recovery of 98% with relative standard deviations of ?1.8% (n = 5). The proposed method
was directly applied to the determination of vanadium in Nile river water and highly polluted industrial wastes. Statistical
treatments of analytical results could not detect any systematic error and showed the high accuracy and precision of the developed
method.
Received November 25, 1999. Revision March 10, 2000. 相似文献
14.
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
15.
A novel procedure was developed for the determination of trace cerium on the basis of anodic adsorption voltammetry of the
Ce(III)–alizarin complexon (ALC) complex at a carbon paste electrode (CPE). The procedure is convenient to determine cerium
individually in the presence of other rare earths because there is a 100 mV difference between the peak potentials of Ce(III)–ALC
and other rare earth(III)–ALC complexes in a supporting electrolyte of 0.08 M HAc–NaAc and 0.012 M potassium biphthalate (pH
4.7) when performing linear-scanning from −0.2 to 0.8 V (vs. SCE) at 100 mV/s. The second-order derivative peak currents are directly proportional to the Ce(III) concentration over
a range of 6.0 × 10−9–3.0 × 10−7 M. The detection limit is as low as 2.0 × 10−9 M (S/N = 3) for a 120 s preconcentration. An RSD of 3.5% was obtained for 15 determinations of Ce(III) at a concentration of 4.0
× 10−8 M on the same CPE surface. The method was applied successfully to the determination of cerium in samples of rare earth nodular
graphite cast iron. 相似文献
16.
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
17.
An “off–on” rhodamine-based fluorescence probe for the selective signaling of Cr(III) has been designed by exploiting the
guest-induced structure transform mechanism. This system shows a sharp Cr(III)-selective fluorescence enhancement response
in 100% aqueous system under physiological pH value and possesses high selectivity against the background of environmentally
and biologically relevant metal ions including Cr(VI), Al(III), Fe(III), Cd(II), Co(II), Cu(II), Ni(II), Zn(II), Mg(II), Ba(II),
Pb(II), Na(I), and K(I). Under optimum conditions, the fluorescence intensity enhancement of this system is linearly proportional
to Cr(III) concentration from 5.0 × 10−8 to 7.0 × 10−6 mol L−1 with a detection limit of 1.6 × 10−8 mol L−1. 相似文献
18.
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
19.
In the presence of carbonate and uranine, the chemiluminescent intensity from the reaction of luminol with hydrogen peroxide
was dramatically enhanced in a basic medium. Based on this fact and coupled with the technique of flow-injection analysis,
a highly sensitive method was developed for the determination of carbonate with a wide linear range. The method provided the
determination of carbonate with a wide linear range of 1.0 × 10−10–5.0 × 10−6 mol L−1 and a low detection limit (S/N = 3) of carbonate of 1.2 × 10−11 mol L−1. The average relative standard deviation for 1.0 × 10−9–9.0 × 10−7 mol L−1 of carbonate was 3.7% (n = 11). Combined with the wet oxidation of potassium persulfate, the method was applied to the simultaneous determination
of total inorganic carbon (TIC) and total organic carbon (TOC) in water. The linear ranges for TIC and TOC were 1.2 × 10−6–6.0 × 10−2 mg L−1 and 0.08–30 mg L−1 carbon, respectively. Recoveries of 97.4–106.4% for TIC and 96.0–98.5% for TOC were obtained by adding 5 or 50 mg L−1 of carbon to the water samples. The relative standard deviations (RSDs) were 2.6–4.8% for TIC and 4.6–6.6% for TOC (n = 5). The mechanism of the chemiluminescent reaction was also explored and a reasonable explanation about chemical energy
transfer from luminol to uranine was proposed.
Figure Chemiluminescence profiles in batch system. 1, Injection of 100 μL of K2CO3 into 1.0 mL luminol-1.0 mL H2O2 solution; 2-3 and 4-5, Injection in sequence of 100 μL of K2CO3 and 100 μL of uranine into 1.0 ml luminol-1.0 mL H2O2 solution; Cluminol = 1.0 × 10−7 mol/L, CH2O2 = 1.0 × 10−5 mol/L, Curanine = 1.0 × 10−5 mol/L, CK2CO3 = 1.0 × 10−7 mol/L except for 4-5 where CK2CO3 = 1.0 × 10−4 mol/L 相似文献
20.
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