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1.
A linear sweep adsorptive stripping voltammetric method for the determination of netilmicin in the presence of formaldehyde
has been proposed for the first time. In the presence of 3.0×10−3 g ml−1 formaldehyde, netilmicin exhibits a sensitive cathodic peak at −1.30 V (vs. the saturated calomel electrode, SCE) in a medium
of Britton–Robinson buffer (pH 8.7) with a scan rate of 100 mV s−1 after a preconcentration period of 120 s at −1.10 V (vs. SCE). The peak current showed a linear dependence on the netilmicin
concentration over the range 4.2×10−9–1.0×10−7 g ml−1. The achieved limits of detection and quantitation were 1.0×10−10 and 3.3×10−10 g ml−1 netilmicin, respectively. It was deduced from the experiments that the amine–aldehyde condensation product formed between
netilmicin and formaldehyde is mainly responsible for the appearance of the peak. The electrochemical behavior of netilmicin
in the presence of formaldehyde has been studied. The method was applied to the direct determination of netilmicin in injectable
formulations and spiked human urine and serum samples.
相似文献
2.
A sensitive adsorptive anodic stripping procedure for the determination of trace zirconium at a carbon paste electrode (CPE)
has been developed. The method is based on adsorptive accumulation of the Zr(IV)-alizarin red S(ARS) complex onto the surface
of the CPE, followed by oxidation of adsorbed species. The optimal experimental conditions include the use of 0.10 mol · L−1 ammonium acetate buffer (pH 4.3), ARS, an accumulation potential of 0.20 V (versus SCE), an accumulation time of 2 min, a
scan rate of 200 mV · s−1 and a second-order derivative linear scan mode. The oxidation peak for the complex appears at 0.69 V. The peak current is
proportional to the concentration of Zr(IV) over the range of 1.0 × 10−9–2.0 × 10−7 mol · L−1, and the detection limit is 3 × 10−10 mol · L−1 for a 2 min adsorption time. The relative standard deviations (n = 8) for 5.0 × 10−8 and 5.0 × 10−9 mol · L−1 Zr(IV) are 3.3 and 4.8%, respectively. The proposed method was applied to the determination of zirconium in ore samples with
satisfactory results. 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 very sensitive electrochemical stripping procedure for azinphos-methyl (Guthion) is reported. Accumulation is achieved by adsorption of the compound on a hanging mercury drop electrode. The adsorptive stripping response was evaluated with respect to accumulation time and potential, concentration dependence, electrolyte and other variables. The determination limit is 0.2 ng ml?1 after 300 s accumulation and 0.4 ng ml?1 after 180 s accumulation. The procedure was applied to spiked river water. 相似文献
5.
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
6.
A very sensitive and selective catalytic adsorptive cathodic stripping procedure for trace measurements of cobalt is presented. The method is based on adsorptive accumulation of the cobalt-MTB (methyl thymol blue) complex onto a hanging mercury drop electrode, followed by reduction of the adsorbed species by voltammetric scan using differential pulse modulation. The reduction current is enhanced catalytically by nitrite. The optimum conditions for the analysis of cobalt include pH 9.0 (ammonia buffer), 2.0 μM methyl thymol blue, 0.8 M sodium nitrite and an accumulation potential of −0.5 V (versus Ag/AgCl). The peak current is proportional to the concentration of cobalt over the entire concentration range tested (0.02–500 ng ml−1) with a detection limit of 0.005 ng ml−1 for an accumulation time of 60 s. The method was applied to determination of cobalt in a mineral water sample and some analytical grade salts with satisfactory results. 相似文献
7.
R. Cornelis J. Versieck L. Mees J. Hoste F. Barbier 《Journal of Radioanalytical and Nuclear Chemistry》1980,55(1):35-43
Vanadium in serum has been investigated by the aid of neutron activation analysis (8 min irradiation at 8·1013 n·cm−2·s−1 in the reactor FR-II of the Kernforschungszentrum in Karlsruhe). The lyophilized samples were dry-ashed before irradiation
and the52V activity extracted after irradiation. The values for V in the sera of 22 healthy males ranged from 0.029–0.939 ng V·ml−1. There is a real assumption that some of the high figures are due to persons being contaminated with V. The 18 healthy females
yielded a mean value of 0.033±0.012 ng V·ml−1 for 17 of them and one additional value of 0.139 ng V·ml−1. These V-data are the lowest ever reported in the literature. The analyses of two packed blood cell samples yielded 0.031
and 0.020 ng·g−1, indicating that about 68% of the total V in blood is present in serum. There was no correlation between the V-content and
age, nor between the V-content and the cholesterol, triglycerides or the lipoprotein fractions in serum. 相似文献
8.
Zenovia Moldovan 《Chemical Papers》2009,63(4):385-390
A simple, selective and sensitive kinetic method for the determination of nitrite in water was developed. The method is based
on the catalytic effect of nitrite on the oxidation of methylene blue (MB) with bromate in a sulfuric acid medium. During
the oxidation process, absorbance of the reaction mixture decreases with the increasing time, inversely proportional to the
nitrite concentration. The reaction rate was monitored spectrophotometrically at λ = 666 nm within 30 s of mixing. Linear
calibration graph was obtained in the range of 0.005–0.5 μg mL−1 with a relative standard deviation of 2.09 % for six measurements at 0.5 μg mL−1. The detection limit was found to be 0.0015 μg mL−1. The effect of different factors such as acidity, time, bromate concentration, MB concentration, ionic strength, and order
of reactants additions is reported. Interference of the most common foreign ions was also investigated. The optimum experimental
conditions were: 0.38 mol L−1 H2SO4, 5 × 10.4 mol L−1 KBrO3, 1.25 × 10.5 mol L−1 MB, 0.3 mol L−1 sodium nitrate, and 25°C. The proposed method was conveniently applied for the determination of nitrite in spiked drinking
water samples. 相似文献
9.
Adsorption and reduction of lovastatin were investigated by cyclic and square-wave voltammetry on a hanging mercury drop electrode
in aqueous solutions over a wide pH range (4–9). The electroreduction of lovastatin proceeds via a surface EC mechanism in
the whole pH range investigated. Using adsorptive stripping voltammetry, the drug yielded a well-defined voltammetric response
in Britton-Robinson buffer, pH 6 at −1.49 V which can be used to determine trace amount of lovastatin. The linear concentration
range of application was 1.0 × 10−8–1.0 × 10−7 M by using an accumulation potential of −0.5 V and a 90 s pre-concentration time. The method has been successfully applied
for the determination of lovastatin in a spiked human serum sample. 相似文献
10.
A facile, sensitive and rapid spectrophotometric method for the determination of nitrite is presented. The method involves
the reaction of nitrite with 4-aminoazobenzene under acidic conditions in the presence of a bromide ion allowing to complete
the diazotization reaction almost instantaneously. The formed diazonium ion is then coupled with acetyl acetone to give bisazo
dye in an aqueous alkaline medium having maximum absorption at 500 nm. The molar absorptivity and Sandell’s sensitivity of
the method were found to be 4.2 × 104 dm3 mol−1 cm−1 and 1.1 ng cm−2, respectively. The system obeys the Beer’s law within the concentration range of 0.1–9 μg of nitrite in the final sample
volume of 10 cm3. Optimum reaction conditions were evaluated and the influence of ionic interference on the determination of nitrite has been
studied. The developed method has been applied in the determination of nitrite in water and soil samples, and the results
were statistically evaluated. 相似文献
11.
Xin Li Houyong Liu Xili He Zhenghua Song 《Applied biochemistry and biotechnology》2010,160(4):1065-1073
It was found that the complex of cytochrome c (Cyt c) and hydrogen peroxide could significantly catalyze the chemiluminescence (CL) reaction from luminol–hydrogen peroxide, and
a sensitive, rapid, and simple CL procedure was proposed for the determination of Cyt c in a flow injection system for the first time. The increment of CL intensity was linear over the concentration of Cyt c ranging from 5 to 700 ng ml−1, with a detection limit of 2 ng ml−1 (3σ). At a flow rate of 2.0 ml min−1, a complete analytical process could be performed in 30 s with a relative standard deviation of less than 4.0%. The proposed
method was applied successfully for the assay of Cyt c in pharmaceutical injections and human serum, and the recoveries were from 98.0% to 108.8% and 92.5% to 109.0%. The possible
mechanism of Cyt c enhanced CL reaction was also discussed. 相似文献
12.
Ali Z. Abu Zuhri Nidal A. Zatar Raqi M. Shubietah Hala H. Arafat 《Mikrochimica acta》2000,134(3-4):153-160
Two methods are described for quantitative determination of nizatidine. The first is a cathodic stripping voltammetric method
which is based on the accumulation of the compound at the hanging mercury drop electrode. The adsorptive stripping response
was evaluated with respect of accumulation time, potential, concentration, pH and other variables. A linear calibration graph
was obtained over the range 3.0×10−8–1.0×10−6 M with a detection limit 3.0×10−8 M after a 20s accumulation time at −0.2 V accumulation potential. On the other hand, it was found that the detection limit
could be lowered to 1.0×10−8 M after 180s accumulation time at −0.2 V accumulation potential. The relative standard deviation was in the range 1.2−2.0%
for six measurements. The tolerance amounts of the common excipients have also been reported.
The second is a spectrophotometric method which is based on the formation and extraction of the ion-pair complex formed between
nizatidine and either bromocresol green or bromothymol blue. The extracted colored ion-pair complexes absorb at 416 nm. The
effect of different factors such as: type of organic solvent, pH, reagent concentration, number of extraction times, shaking
time, temperature and the tolerance amount of the common excipients have been reported. The calibration graph was linear in
the range 6.0×10−7–1.8×10−5 M with a detection limit of 6.0×10−7 M and molar absorptivity of 2.1×104 lċmol−1ċcm−1 when using bromocresol green, while the calibration graph was linear in the range 3.0×10−7–1.1×10−5 M with a detection limit of 3.0×10−7 M and molar absorptivity of 3.2×104 lċmol−1ċcm−1 when using bromothymol blue. The spectrophotometric methods offer alternative methods with reasonable sensitivity, selectivity
and accuracy with relative standard deviation in the range 2.1−6.0% and 1.2−4.7% (for six measurements) when using bromothymol
blue and bromocresol green, respectively. The proposed two methods were applied for the determination of nizatidine in commercially
available dosage forms. A comparison between the voltammetric and the extraction-spectrophotometric methods was also reported.
Received April 19, 1999. Revision August 30, 1999. 相似文献
13.
Sánchez-Martínez ML Aguilar-Caballos MP Eremin SA Gómez-Hens A 《Analytical and bioanalytical chemistry》2006,386(5):1489-1495
The potential of long-wavelength fluorimetry when used as the detection system in immunoaffinity chromatography is assessed
for the first time by applying this approach to the analysis of water and sludge samples. Nile blue (NB) was used to synthesize
a long-wavelength fluorescent tracer for linear alkylbenzenesulfonates (LASs) using the carbodiimide method, in which the
amino group of NB is covalently coupled to the activated carboxylic acid group of a LAS mimic with N-hydroxysuccinimide and dicyclohexylcarbodiimide. The method consists of the injection of a pre-incubated mixture containing
linear sodium 4-dodecylbenzenesulfonate (LDS; used as the LAS model), anti-LAS antibodies, and the long-wavelength tracer
into a commercial Protein G column. Free and bound tracer fractions are separated in the column, and the peak height of the
immunochromatogram (corresponding to the free tracer) is directly measured at 626 nm (λ
ex) and 674 nm (λ
em), and then correlated to the analyte concentration. It is not necessary to perform an elution step immediately after every
sample application. The dynamic range of the method is 0.05–2.5 μg ml−1 LDS, and the detection limit is 15 ng ml−1. The precision, expressed as the relative standard deviation, is 4.8–6.4%. Other surfactants (sodium dodecylsulfate and Triton
X-100) do not cause interference. The recoveries obtained by applying the method to the analysis of water (ground- and wastewater)
and sludge (primary and activated) samples ranged from 86.0 to 111.3%. Water sample analysis included an initial solid-phase
extraction step, which cleaned up the samples and improved the detection limit fivefold. 相似文献
14.
Nigović B 《Analytical and bioanalytical chemistry》2006,384(2):431-437
The electrochemical reduction and adsorptive voltammetric behaviour of pravastatin have been studied by means of cyclic and
square-wave voltammetry at a hanging mercury-drop electrode in electrolytes of different pH. Within the entire pH range (2.0–9.0)
in Britton–Robinson buffer, pravastatin gave rise to a single voltammetric peak in the potential interval from −1.22 to −1.44
V, depending on pravastatin concentration. It was found that the reduction of pravastatin proceeds via a relatively stable
intermediate, which is transformed to the final electroinactive product by a coupled chemical reaction or can be re-oxidized
back to pravastatin. The rate of chemical transformation is controlled by the proton concentration. The electrode mechanism
has the properties of a surface redox reaction. A sensitive analytical method for trace analysis of pravastatin based on the
adsorptive stripping technique has been developed. The calibration plot was linear in the range 8×10−8–5×10−7 mol L−1. Application of the square-wave voltammetric method to determination of pravastatin in a pharmaceutical dosage form, without
sample pretreatment, resulted in acceptable deviation from the stated concentration. 相似文献
15.
Chen HQ Wang L Liu Y Wu WL Liang AN Zhang XL 《Analytical and bioanalytical chemistry》2006,385(8):1457-1461
A new fluorescence method for the detection of proteins with novel composite nanoparticles (CdS/PPA) has been developed. The
composite nanoparticles have been prepared through an in-situ polymerization method under ultrasonic irradiation. The surface
of the composite nanoparticles was covered with functional groups (-COOH). These groups may play a major role in the improving
the water solubility and biocompatibility of the nanoparticles. The composite particles is combined with proteins in NaAc-HCl
buffer solution (pH=1.99), which can result in strong fluorescence, and the response is linearly proportional to the concentration
of proteins. In λem/λex=650 nm/365 nm place (the stoke’ shift is 285 nm), its fluorescent strength reaches the maximum. Under
the optimum conditions, the linear range is 0.10–20.0 μg·ml−1 with the detection limit of 41 ng·ml−1 for HSA, and 0.10–15.0 μg·ml−1 with the detection limit of 35 ng·ml−1 for Human γ-IgG . The method has been applied to the determination of the total protein in human serum samples collected
from the hospital and the results are satisfactory. 相似文献
16.
Li C Wen D Zhang J Chen Z Cong W Rao Z Liu H 《Analytical and bioanalytical chemistry》2006,386(7-8):1985-1993
Metabolism of four tobacco-specific N-nitrosamines (TSNAs), N′-nitrosonornicotine (NNN), N′-nitrosoanatabine (NAT), N′-nitrosoanabasine (NAB), and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) has been studied by solid-phase extraction
(SPE) and liquid chromatography–tandem mass spectrometry (LC–MS–MS). 4-(Methylnitrosamino)-4-(3-pyridyl)-1-butanol (iso-NNAL)
was used as internal standard. SPE and LC–MS–MS was found to be a rapid, simple, sensitive, and selective method for analysis
of TSNAs in rabbit serum. The relative standard deviation (R.S.D., n = 6) for analysis of 5 ng mL−1 and 0.5 ng mL−1 standards and of serum sample spiked with 5 ng mL−1 standards of five TSNAs was 2.1–11% and recovery of 5 ng mL−1 standards from serum was 100.2–112.9%. A good linear relationship was obtained between peak area ratio and concentration
in the range of 0.2–100 ng mL−1 for NNAL and 0.5–100 ng mL−1 for other four TSNAs, with correlation coefficients (R
2) >0.99 (both linear and log–log regression). Detection limits for standards in solvent were between 0.04 and 0.10 ng mL−1. Doses of TSNAs administered to rabbits via the auricular vein were 4.67 μg kg−1 and 11.67 μg kg−1, in accordance with the different levels in cigarettes. Metabolic curves were obtained for the four TSNAs and for 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol
(NNAL), a metabolite of NNK; on the basis of these curves we modeled metabolic kinetic equations for these TSNAs by nonlinear
curve fitting. 相似文献
17.
K. K. Verma A. J. H. Louter A. Jain E. Pocurull J. J. Vreuls U. A. Th. Brinkman 《Chromatographia》1997,44(7-8):372-380
Summary On-line solid-phase extraction-gas chromatographyion-trap tandem mass spectrometry (SPE-GC-MS/MS) has been used for the trace-level
determination of polar and apolar pesticides. The SPE-GC interface, an Autoloop 2000, was operated at an injection temperature
of 90°C which permitted the determination of thermolabile pesticides such as carbofuran and carbaryl. Rectilinear calibration
curves were obtained for the analytes tested over a range of 0.1–500 ng L−1, using a sample volume of 10–100 mL for enrichment on an SPE cartridge packed with styrene-divinylbenzene copolymer. The
detection limits for the pesticides were in the 0.01–4 ng L−1 range. For a number of pesticides acceptable tandem mass spectra were obtained at levels as low as 0.1 ng L−1 level in real-life water samples.
As a demonstration of the applicability of this technique for inorganic anions, bromide and nitrite were converted into 4-bromoacetanilide
and 2-phenylphenol, respectively. The reaction products were pooled and subjected to simultaneous analysis by the present
method using full-scan mass spectrometric detection. The detection limits were 0.3 and 2 ng L−1, respectively. 相似文献
18.
Design of a field flow system for the on-line spectrophotometric determination of phosphate, nitrite and nitrate in natural water and wastewater 总被引:1,自引:0,他引:1
Ioannis A. Tsoulfanidis George Z. Tsogas Dimosthenis L. Giokas Athanasios G. Vlessidis 《Mikrochimica acta》2008,160(4):461-469
This study describes the design and optimisation of a field flow system for the in-situ collection and on-line determination
of phosphate, nitrate and nitrite by flow injection analysis-spectrophotometry. The method is based on the initial determination
of phosphate as its phosphoantimonylmolybdenum blue complex which is then oxidized on-line by nitrite and the decrease in
absorbance is monitored at 880 nm. Nitrate is determined as the difference between total and initial nitrite content in a
separate flow after reduction to nitrite in a cadmium reductive column. The calibration curves were linear in the range 0–2.00 mg L−1 P-phosphate, 0–10.00 mg L−1 nitrite and 0–7.00 mg L−1 nitrate with correlation coefficients of 0.9979, 0.9993 and 0.9995, respectively. The detection limits, calculated as 3S/N,
were 0.15 mg L−1 for P-phosphate, 0.17 mg L−1 for nitrite and 0.09 mg L−1 for nitrate. The reproducibility was below 3.0% (n = 7). Method validation in the analysis of natural water and wastewater samples revealed that it can efficiently be applied
to the determination of the target analytes, with recoveries in the range of 92–108%.
Correspondence: Athanasios G. Vlessidis, Laboratory of Analytical Chemistry, Department of Chemistry, University of Ioannina,
Ioannina 45110, Greece 相似文献
19.
Qiong He Tian Gan Dongyun Zheng ShengShui Hu 《Journal of Solid State Electrochemistry》2010,14(6):1057-1064
Simple and sensitive electrochemical method for the determination of nitrite, based on a nano-alumina-modified glassy carbon
electrode (GCE), is described. Nitrite yields a well-defined oxidation peak whose potential is 0.74 V at the nano-alumina-coated
GCE in 0.1 mol L−1 phosphate buffer (pH 5.0). Compared with bare GCE, the nano-alumina-modified GCE has evident catalytic effect towards the
oxidation of nitrite, and its peak current can be significantly enhanced. Some of the experimental parameters were optimized
for the determination of nitrite. The oxidation peak current was proportional to nitrite concentration in the range of 5.0 × 10−8–1.1 × 10−3 mol L−1, and a detection limit of 1.0 × 10−8 mol L−1 was obtained. This method has been successfully used to the determination of nitrite in sausage sample. Furthermore, results
obtained by the method have been compared with spectrophotometric method. 相似文献
20.
A high-performance liquid chromatography–UV method for determining DCJW concentration in rat plasma was developed. The method
described was applied to a pharmacokinetics study of intramuscular injection in rats. The plasma samples were deproteinized
with acetonitrile in a one-step extraction. The HPLC assay was carried out using a VP-ODS column and the mobile phase consisting
of acetonitrile–water (80:20, v/v) was used at a flow rate of 1.0 mL min−1 for the effective eluting DCJW. The detection of the analyte peak area was achieved by setting a UV detector at 314 nm with
no interfering plasma peak. The method was fully validated with the following validation parameters: linearity range 0.06–10 μg mL−1 (r > 0.999); absolute recoveries of DCJW were 97.44–103.46% from rat plasma; limit of quantification, 0.06 μg mL−1 and limit of detection, 0.02 μg mL−1. The method was further used to determine the concentration–time profiles of DCJW in the rat plasma following intramuscular
injection of DCJW solution at a dose of 1.2 mg kg−1. Maximum plasma concentration (C
max) and area under the plasma concentration–time curve (AUC) for DCJW were 140.20 ng mL−1 and 2405.28 ng h mL−1. 相似文献