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1.
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
2.
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
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.
A novel approach to the detection of estriol using a flow injection system coupled to enhanced chemiluminescent immunoassay
was developed based on noncompetitive immunoassay formats. A conjugated estriol-ovalbumin immobilized immunoaffinity column
was inserted into the flow system to trap the unbound horseradish peroxidase (HRP)-labeled antibody after an off-line incubation
of estriol and HRP-labeled anti-estriol antibody. The trapped enzyme conjugate was detected by the injection of chemiluminescent
substrates to produce enhanced chemiluminescence. The linear range for the determination of estriol is 10.0 to 400 ng · mL−1 with a correlation coefficient of 0.996 and a detection limit of 5.0 ng · mL−1. The total time for sampling and chemiluminescent detection of one sample is 400 seconds after 30 min of pre-incubation.
The results for pregnancy serum samples obtained by this method are in good agreement with those obtained using ELISA. 相似文献
5.
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
6.
Ródenas-Torralba E Morales-Rubio A de la Guardia M 《Analytical and bioanalytical chemistry》2005,383(1):138-144
An automated and greener spectrophotometric procedure has been developed for the determination of phenol in water at 700 nm.
The method uses the reaction between phenol, sodium nitroprusside, and hydroxylamine hydrochloride in a buffered medium at
pH 12.3. The flow manifold comprises four solenoid micro-pumps employed for sample and reagent introduction into the reaction
coil and to transport the colored product formed to the detector. The linear dynamic range was 50–3,500 ng mL−1 (R = 0.99997; n = 6) and the method provided a limit of detection (3σ) of 13 ng mL−1. The sampling throughput was estimated to be 65 measurements per hour and the coefficient of variation was 0.5% (n = 10) for a 1.0 μg mL−1 phenol concentration. Recoveries of 92–105% were obtained for phenol determination in spiked water samples at concentration
levels from 50 to 5,000 ng mL−1. The use of multicommutation reduced the reagent consumption 25-fold, the sample consumption 225-fold, and the waste generation
30-fold compared with the batch procedure. The proposed method is an environmentally friendly alternative to the official
4-aminoantipyrine method since it avoids the use of chloroform. 相似文献
7.
Viñas P López-García I Bravo-Bravo M Briceño M Hernández-Córdoba M 《Analytical and bioanalytical chemistry》2012,403(4):1059-1066
A miniaturized dispersive liquid–liquid microextraction (DLLME) procedure coupled to liquid chromatography (LC) with fluorimetric
detection was evaluated for the preconcentration and determination of thiamine (vitamin B1). Derivatization was carried out by chemical oxidation of thiamine with 5 × 10−5 M ferricyanide at pH 13 to form fluorescent thiochrome. For DLLME, 0.5 mL of acetonitrile (dispersing solvent) containing
90 μL of tetrachloroethane (extraction solvent) was rapidly injected into 10 mL of sample solution containing the derivatized
thiochrome and 24% (w/v) sodium chloride, thereby forming a cloudy solution. Phase separation was carried out by centrifugation, and a volume of
20 μL of the sedimented phase was submitted to LC. The mobile phase was a mixture of a 90% (v/v) 10 mM KH2PO4 (pH 7) solution and 10% (v/v) acetonitrile at 1 mL min−1. An amide-based stationary phase involving a ligand with amide groups and the endcapping of trimethylsilyl was used. Specificity,
linearity, precision, recovery, and sensitivity were satisfactory. Calibration graph was carried out by the standard additions
method and was linear between 1 and 10 ng mL−1. The detection limit was 0.09 ng mL−1. The selectivity of the method was judged from the absence of interfering peaks at the thiamine elution time for blank chromatograms
of unspiked samples. A relative standard deviation of 3.2% was obtained for a standard solution containing thiamine at 5 ng mL−1. The esters thiamine monophosphate and thiamine pyrophosphate can also be determined by submitting the sample to successive
acid and enzymatic treatments. The method was applied to the determination of thiamine in different foods such as beer, brewer’s
yeast, honey, and baby foods including infant formulas, fermented milk, cereals, and purees. For the analysis of solid samples,
a previous extraction step was applied based on an acid hydrolysis with trichloroacetic acid. The reliability of the procedure
was checked by analyzing a certified reference material, pig’s liver (CRM 487). The value obtained was 8.76 ± 0.2 μg g−1 thiamine, which is in excellent agreement with the certified value, 8.6 ± 1.1 μg g−1. 相似文献
8.
Protein can greatly enhance the fluorescence of curcumin (CU) in the presence of sodium dodecyl benzene sulfonate (SDBS).
Experiments indicate that under the optimum conditions, the enhanced intensity of fluorescence is proportional to the concentration
of proteins in the range of 0.0050–20.0 μg mL−1 for bovine serum albumin (BSA), 0.080–20.0 μg mL−1 for human serum albumin (HSA), and 0.040–28.0 μg mL−1 for egg albumin (EA). Their detection limits (S/N=3) are 1.4 ng mL−1, 20 ng mL−1, and 16 ng mL−1, respectively. The method has been satisfactorily used for the determination of proteins in actual samples. In comparison
with most of fluorimetric methods, this method is quick and simple, has high sensitivity and good stability. The interaction
mechanism is also studied. 相似文献
9.
A sensitive catalytic method is developed for the spectrophotometric determination of oxalic acid. It is based on the catalytic
action of oxalic acid on a new indicator reaction – the oxidation of Bromophenol Blue by dichromate in dilute sulfuric acid
medium. The reaction rate is monitored spectrophotometrically by measuring the absorbance at 600 nm after quenching the reaction
with sodium hydroxide. A calibration graph from 0.1 to 8.0 μg mL−1 of oxalic acid and a detection limit of 0.04 μg mL−1 was obtained. The applicability of this method was demonstrated by the determination of oxalic acid in water extracts from
vegetables such as spinach, mushrooms and fresh kidney beans.
Received October 18, 1999. Revision June 14, 2000. 相似文献
10.
A simple, rapid, selective, sensitive and economical method has been developed for the simultaneous determination of trace
amounts of palladium and nickel in aqueous methanolic medium using 2-(2-thiazolylazo)-5-dimethylam inobenzoic acid as an analytical
reagent by first derivative spectrophotometr y. Palladium is determined by measuring base to peak distance at λ=695.0 nm while
nickel is estimated by zero crossing method in the mixture. The linearity is maintained between 0.12–1.75 μg mL−1 for palladium and 0.07–1.60 μg mL−1 for nickel in the pH range 2.8–7.2 and 3.4–8.8 respectively. Seven replicate determinations of 1.0 μ g mL−1 of palladium and 0.8 μg mL−1 of nickel in a mixture give a mean signal height of 0.391 for Pd and 0.541 for Ni with relative standard deviations of 0.9%
and 1.2%, respectively. The sensitivity of the proposed method is 0.391 (dA/dλ)/(μg mL−1) for palladium and 0.685 (dA/dλ)/(μg mL−1) for nickel. Various parameters have been optimised for the simultaneous determination of palladium and nickel in various
complex samples.
Received March 30, 1999. Revision November 25, 1999. 相似文献
11.
The use of olaquindox (OLA) as an additive in animal feedstuffs has been prohibited in the European Union and many other countries.
In this study, a highly sensitive and specific indirect competitive enzyme-linked immunosorbent assay (ELISA) for determination
of OLA in animal feed samples was developed. OLA was activated by N′N-carbonyldiimidazole and coupled with bovine serum albumin (BSA) and ovalbumin (OVA). It was found that the sensitivity and
specificity of the two antisera were very similar, with the IC50 values of 16 ng mL−1 and 19 ng mL−1, respectively. Cross-reactivity was less than 35% for four structurally related compounds and no recognition of five other
antibiotics was observed. The better antiserum I was selected for further experiments, for example testing stability, solvent
effect, accuracy, and precision. The IC50 value for eight standard curves was in the range 12–18 ng mL−1 and the LOD at a signal-to-noise ratio of 3 (S/N = 3) was 0.31 ± 0.11 ng mL−1. The ELISA tolerated 5% methanol without significant influence on IC50 value. The recoveries of spiked OLA in five different animal feed types including auxin, pig complex feed, fish complex feed,
broiler concentrated feed, and pig premix feed were in the range 88.3–119.0% and the intra-assay relative standard deviation
(RSD) was within 4.7–33.5% (n = 3). The ELISA for unspiked feed samples was confirmed by high-performance liquid chromatography (HPLC), with a high correlation
coefficient of 0.9862 (n = 5). The proposed ELISA could be a feasible quantitative/screening method for OLA analysis in feed samples with the properties
of high sensitivity, specificity, simplicity of sample pretreatment, high sample throughput, and low expense.
Figure Polyclonal antibody based ELISA for detection of olaquindox 相似文献
12.
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
13.
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
14.
Determination of eight penicillins in serum from cattle and pigs by generic HPLC method 总被引:1,自引:0,他引:1
Summary An HPLC method was developed for determination of amoxicillin, penicillin G, penicillin V, ampicillin, oxacillin, cloxacillin,
nafcillin and dicloxacillin in serum from pigs and cattle. Serum was cleaned up by solid-phase extraction (SPE), ultra-filtered
and derivatised. The method was linear in the range tested up to 2000 ng mL−1 of individual penicillins in serum. Limits of detection were 11–14 ng mL−1. Mean recoveries were 90–103% in the range 20–2000 ng mL−1. The relative repeatability, standard deviation was <10% at 20 ng mL−1 level and <6% in the range 100–2000 ng mL−1. 相似文献
15.
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
16.
Study of a toxin–alkaline phosphatase conjugate for the development of an immunosensor for tetrodotoxin determination 总被引:2,自引:0,他引:2
This paper describes a direct competitive immunoenzymatic spectrophotometric assay (ELISA) for tetrodotoxin (TTX) determination
and the adaptation of this method for use in an electrochemical assay format. The novelty of this work involves the use of
the antigen labelled with alkaline phosphatase (AP); this conjugate was prepared in our laboratory as there is no commercially
available conjugate of any kind for TTX. The new conjugate was characterized in terms of its affinity for the specific antibody
as well as the residual concentration and the residual activity of the enzyme (AP) incorporated as label. The proposed method
based on the new conjugate showed satisfactory results for TTX determination: for the spectrophotometric method the dynamic
range was 4–15 ng mL−1 with a limit of detection (LOD) of 2 ng mL−1 (R=0.9247), whereas for the electrochemical protocol the dynamic range was 2–50 ng mL−1 and the LOD was1 ng mL−1. 相似文献
17.
Summary A high-performance liquid chromatographic method with amperometric detection has been developed for the determination of levels
of clozapine (CLZ) and its active metabolite N-desmethylclozapine (DMC) in human plasma. The analysis was performed on a 5
μm C8 reversed phase column (150×4.6 mm i.d.), with acetonitrile-phosphate buffer (pH 3.5), as the mobile phase. The detection
voltage was +800 mV and the cell and column temperature were 50°C. Linear responses were obtained between 2 ng mL−1 and 100 ng mL−1. Absolute recovery for both clozapine and desmethylclozapine exceeded 88% and the detection limit was 1 ng mL−1. Repeatability, intermediate precision and accuracy were satisfactory. The method, which is rapid, sensitive and selective,
has been applied to therapeutic drug monitoring in schizophrenic patients following administration of Leponex? tablets. In 21 patients in steady state at a mean daily clozapine dosage of 358 mg (ranging from 150 to 500 mg day−1), clozapine levels averaged 379 ng mL−1 (ranging from 102 to 818 ng mL−1) and DMC levels averaged 233 ng mL−1 (ranging from 70 to 540 ng mL−1). The method requires only a very small amount of plasma (100 μL), and thus it is suitable for pharmacokinetic studies, as
well as for therapeutic drug monitoring. 相似文献
18.
A novel method for the determination of proteins at nanogram levels was proposed based on the decrease of resonance light
scattering (RLS) signal resulting from the interaction of dibromo-o-nitrophenylfluorone (DBONPF)-sodium lauroyl glutamate
(SLG) with proteins. At pH 2.97, the decrease RLS intensity was proportional to the concentration of proteins in the range
of nanogram levels with 3σ detection limits being 3.4 ng mL−1 for bovine serum albumin (BSA), 1.7 ng mL−1 for human serum albumin (HSA), 4.1 ng mL−1 for γ-globulin (γ-IgG), 4.4 ng mL−1 for egg albumin, 6.2 ng mL−1 for pepsin (Pep) and 3.7 ng mL−1 for α-chymotrypsin (Chy). The method is no protein-to-protein variability, simple, rapid, practical and relatively free
from interference from coexisting substance, as well as much more sensitive than most of the reported methods. The proposed
method was successfully applied to determine total protein in human serum samples. 相似文献
19.
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
20.
A sensitive chemiluminescence method, based on the enhancive effect of norfloxacin on the reaction between luminol and dissolved
oxygen in a flow injection system, was proposed for the determination of norfloxacin. The increment of the chemiluminiscence
intensity was proportional to the concentration of norfloxacin, giving a calibration graph linear over the concentration from
0.4 ng mL−1 to 400.0 ng mL−1 (r
2 = 0.9988) with the detection limit of 0.1 ng mL−1 (3 × σ
noise). At the flow rate of 2.0 mL min−1, a complete determination of norfloxacin, including sampling and washing, could be accomplished in 30 s with the relative
standard deviation lower than 3.0 %. The proposed method was applied successfully to determine norfloxacin in pharmaceuticals,
human urine, and serum. Possible mechanism of the reaction was also discussed. 相似文献