共查询到20条相似文献,搜索用时 31 毫秒
1.
R. S. Das P. S. Chakraborty S. N. Bhattacharyya 《Journal of Radioanalytical and Nuclear Chemistry》1976,34(2):249-259
Gold was determined in some selected rock samples by neutron activation analysis. The analysis was carried out both in destructive
and non-destructive ways followed by γ-ray spectrometry. The amounts of gold that were determined in the respective rock samples
varied in the range 10−4–10−6%. Besides gold, some other trace constituents such as As, Ag, Sb, W, Se, La, Sm, etc. were also detected and their approximate
order of occurrence was determined. 相似文献
2.
V. G. Torgov T. M. Korda M. G. Demidova E. A. Gus’kova G. L. Bukhbinder 《Journal of Analytical Chemistry》2009,64(9):877-885
A procedure is developed for determining all platinum-group metals (PGM) and gold (10−7 to 10−4%). It includes the autoclave digestion of samples with the transfer of metals into a hydrochloric acid medium without losing
osmium and ruthenium, group 10- to 20-fold extraction preconcentration of precious metals with the removal of matrix interfering
elements to a factor of 105–106, and the analysis of the group back extract of PGM and gold by ICP AES. A method is proposed for the quantitative back extraction
of all PGM and gold from a group extract in two steps of consecutively washing the extract with ammonia solutions and thiourea.
The procedure is tested on seven GSO samples and technological objects. It is shown that ICP MS can be used for the analysis
of group back extracts of PGM and gold. 相似文献
3.
D. I. Leipuskaya V. I. Drynkin D. M. Voinkov I. F. Brovchuk K. I. Ilyasova B. V. Belenki 《Journal of Radioanalytical and Nuclear Chemistry》1980,57(2):407-416
A method has been worked out of multi-elemental instrumental neutron-activation analysis INAA of small weights some mg of
monomineral fractions of sulfide minerals pyrites, galenites, chalcopyrites, arsenopyrites, bornites, chalcosines and quartzes.
The samples were irradiated in a nuclear reactor under a flux of 1.3·1013 n·cm−2·s−1. For measuring the gamma radiation of the exposed samples Ge(Li) gamma-spectrometers with semiconductor detectors were used.
Determined in sulfide monofractions were the elements: Co, Sc, Ag, Se, Sb, Cr, Fe, Zr; rare-earth elements: Ce, Sm, Eu and
others at content levels of 10−1−10−4%. In quartzes they were: Mn, Na, Sb, Cr, Sc, Fe, Co at content levels of 10−5−10−7% and Au to n×10−9%. A special method has been worked out for the determination of In in sulfides with the irradiation of samples in a cadmium
screen. An example is cited of using the method for studying some peculiar features of the genetics of copper pyrite deposits.
The data on the distribution of admixture elements in sulfide monofractions produced in this work made it possible to conclude
that the oreformation in the deposits has a stage-by-stage character. 相似文献
4.
A collimated neutron beam capable of providing a thermal neutron flux of 4.75·107 n·cm−2·sec−1 has been used to analyze alloy samples of 1–5 g during relatively short irradiation times of 30 min by the use of neutron
capture gamma-ray spectrometry. The analyses were performed by using a mathematical treatment that relates the count ratio
of every constituent present in the matrix with the concentration and thus it requires no standards. The technique was applied
to the analysis of steel and gold alloy samples. Errors ranged from 0.8%–10%. 相似文献
5.
An amperometric sensor for the determination of indole-3-acetic acid (IAA) based on the CeCl3-DHP film modified gold electrode was developed. CeCl3 was dissolved into water in the presence of dihexadecyl hydrogen phosphate (DHP). The IAA sensor was prepared via evaporating
solvent of the CeCl3-DHP dispersion on the gold electrode surface. The amperometric response of IAA on the CeCl3-DHP film modified gold electrode was investigated. The experimental results indicate that the passivation of the electrode
due to the adsorption of the oxidation product of IAA decreases significantly at the CeCl3-DHP film modified gold electrode, in contrast to that at the bare and the DHP modified gold electrode. The experimental parameters
were optimized and an electrochemical method for the determination of IAA was established. The oxidation peak current is linearly
with the concentration of IAA from 1 × 10−7 to 2 × 10−5 mol l−1 and the detection limit is 3 × 10−8 mol l−1. The relative standard deviation of eight measurements is 3.2% for 5 × 10−7 mol l−1 IAA. The IAA in plant leaves were extracted and determined by the IAA sensor. 相似文献
6.
There is an increasing need to assess the harmful effects of heavy-metal-ion pollution on the environment. The ability to
detect and measure toxic contaminants on site using simple, cost effective, and field-portable sensors is an important aspect
of environmental protection and facilitating rapid decision making. A screen-printed gold sensor in a three-electrode configuration
has been developed for analysis of lead(II) by square-wave stripping voltammetry (SWSV). The working electrode was fabricated
with gold ink deposited by use of thick-film technology. Conditions affecting the lead stripping response were characterised
and optimized. Experimental data indicated that chloride ions are important in lead deposition and subsequent analysis with
this type of sensor. A linear concentration range of 10–50 μg L−1 and 25–300 μg L−1 with detection limits of 2 μg L−1 and 5.8 μg L−1 were obtained for lead(II) for measurement times of four and two minutes, respectively. The electrodes can be reused up to
20 times after cleaning with 0.5 mol L−1 sulfuric acid. Interference of other metals with the response to lead were also examined to optimize the sensor response
for analysis of environmental samples. The analytical utility of the sensor was demonstrated by applying the system to a variety
of wastewater and soil sample extracts from polluted sites. The results are sufficient evidence of the feasibility of using
these screen-printed gold electrodes for the determination of lead(II) in wastewater and soil extracts. For comparison purposes
a mercury-film electrode and ICP–MS were used for validation. 相似文献
7.
V. G. Lambrev V. V. Nekrasov G. G. Akalaev N. N. Rodin I. C. Dneprovsky 《Journal of Radioanalytical and Nuclear Chemistry》1970,6(2):431-436
A procedure for the instrumental neutron activation analysis of micro-ingots of alloys containing In, Sb, Au, Ga, Ni, Sn and
Bi is proposed. The non-destructive analysis of the irradiated samples is performed by γ-spectrometry techniques including
one-crystal scintillation detectors, dual-crystal sum-coincidence scintillation detectors and Ge(Li) semiconductor detectors.
As a result, the cumbersome operations of radiochemical separation can be eliminated. The sensitivity of quantitative determinations
using scintillation detectors in alloys of the above composition is 10−10 g for indium, gold, antimony and gallium and 10−6 g for nickel and tin. The use of semiconductor detectors yields sensitivities of 10−10 g for indium and gold and 10−9 g for gallium and antimony. 相似文献
8.
Klaus-Michael Ochsenkühn Theopisti Lyberopoulou G. Koumarianou Maria Ochsenkühn-Petropoulou 《Mikrochimica acta》2008,160(4):485-492
In the time period from June 2005 to May 2006 in 42 sampling campaigns 84 filter samples of airborne particulate matter, coarse
(PM10–2.5) and fine (PM2.5), were collected using a Gent stacked filter unit in the coastal industrial area of Aspropyrgos in Attica, Greece. The average
PM10 (PM10–2.5 + PM2.5) concentration was found to be 66 μg · m−3, exceeding more than 1.6 times the annual limit of 40 μg · m−3. The samples were analysed for Cl−, NO3
−, SO4
2−, Ca2+, Mg2+, Na+, K+ and NH4
+ using ion chromatography. The data were compared with results obtained with other spectrometric methods, such as inductively
coupled plasma-atomic emission spectrometry, atomic absorption spectrometry, energy dispersive X-ray fluorescence and reflectometry.
The determined average ionic content comprised about 44% of the PM10 mass. The ionic composition, as well as the possible matrix compounds in both fractions were evaluated by dividing the sampling
period into summer and winter season. In the PM10–2.5/PM2.5 fraction in summer time the concentrations of Ca2+, Mg2+ and NO3
− were enriched in the coarse fraction. In winter time all species were enriched in the coarse fraction, especially Ca2+, Cl− and NO3
−. NH4
+ was constantly higher in the fine fraction in summer as well as in winter time. Factor analysis was applied to obtain correlations
between cations and anions leading to matrix compounds in both fractions. From the evaluation of the results obtained, some
of the local air pollution sources could be identified.
Correspondence: Klaus-Michael Ochsenkühn, Laboratory for Trace Element Studies, Institute of Physical Chemistry, NCSR “Demokritos”,
Aghia Paraskevi 15310, Athens, Greece 相似文献
9.
Zhaoyang Wu Xiaolei Zhang Yunhui Yang Guoli Shen Ruqin Yu 《Frontiers of Chemistry in China》2006,1(2):183-187
A sensitive nicotine sensor based on a molecularly imprinted electropolymer of o-aminophenol is proposed and its configuration
and performance are studied in detail. On the condition of weak acidity, the sensitive layer was prepared by electropolymerization
of o-aminophenol on a gold electrode in the presence of the template (nicotine). The sensor exhibits good selectivity and
sensitivity to nicotine. The determination limit is 2.0×10−7 mol/L and a linear relationship between the current and concentration is found in the range of 4.0×10−7 ∼ 3.3 ×10−5 mol/L. The sensor has also been applied to the analysis of nicotine in tobacco samples with recovery rates ranging from 99.0%
to 102%.
__________
Translated from Journal of Hunan university (Nature Science), 2005, 32(3) (in Chinese) 相似文献
10.
Jun Yue Bai Liang Wang Hong Jing Wang Peng Fei Huang Yu Qing Zhao Sheng Di Fan 《Mikrochimica acta》2006,156(3-4):321-326
The electrochemical behavior of epinephrine (EP) at a mercaptoacetic acid (MAA) self-assembled monolayer modified gold electrode
was studied. The MAA/Au electrode is demonstrated to promote the electrochemical response of epinephrine by cyclic voltammetry.
The possible reaction mechanism is also discussed. The diffusion coefficient D of EP is 6.85 × 10−6 cm2 s−1. In 0.1 mol L−1 phosphate buffer (pH 7.20), a sensitive oxidation peak was observed at 0.177 V, and the peak current is proportional to the
concentration of EP in the range of 1.0 × 10−5–2.0 × 10−4 mol L−1 and 1.0 × 10−7–1.0 × 10−6 mol L−1. The detection limit is 5 × 10−8 mol L−1. The modified electrode is highly stable and can be applied to the determination of EP in practical injection samples. The
method is simple, quick, sensitive and accurate. 相似文献
11.
de la Escosura-Muñiz A González-García MB Costa-García A 《Analytical and bioanalytical chemistry》2006,384(3):742-750
A new electroactive label has been used to monitor immunoassays in the determination of human serum albumin (HSA) using glassy-carbon
electrodes as supports for the immunological reactions. The label was a gold(I) complex, sodium aurothiomalate, which was
bound to rabbit IgG anti-human serum albumin (anti-HSA-Au). The HSA was adsorbed on the electrode surface and the immunological
reaction with gold-labelled anti-HSA was then performed for one hour by non-competitive or competitive procedures. The gold(I)
bound to the anti-HSA was electrodeposited in 0.1 mol L−1 HCl at −1.00 V for 5 min then oxidised in 0.1 mol L−1 H2SO4 solution at +1.40 V for 1 min. Silver electrodeposition at −0.14 V for 1 min followed by anodic stripping voltammetry were
then performed in aqueous 1.0 mol L−1 NH3–2.0×10−4 mol L−1 AgNO3. For both non-competitive and competitive formats, calibration plots in the ranges 5.0×10−10 to 1.0×10−8 mol L−1 and 1.0×10−10 to 1.0×10−9 mol L−1 HSA, respectively, with estimated detection limits of 1.5×10−10 mol L−1 (10 ng mL−1) and 1.0×10−10 mol L−1 (7 ng mL−1), respectively, were obtained. Levels of HSA in two healthy volunteer urine samples were also evaluated, using both immunoassay
formats. 相似文献
12.
A polyclonal antibody against ochratoxin A (OTA) was produced from rabbits immunized with the OTA–BSA conjugate. A competitive
direct enzyme-linked immunosorbent assay (cdELISA) and a membrane-base colloidal gold immunoassay in flow-through format were
developed for the rapid detection of OTA in various food matrices. In the cdELISA, the concentration causing 50% inhibition
was 0.07 ng mL−1, and the effects of different chemical conditions (ionic strength, pH value, and organic solvent) were studied. The sensitivity
of the assay was higher than those previously reported. A simple, rapid, and efficient extraction method was developed and
74–110% recoveries of spiked samples were obtained. Fifty percent methanol extracts of some food samples such as barley, wheat,
oat, corn, rice, and raisins could be analyzed directly by immunoassay after dilution in PBS; grape juice and beer samples
could be analyzed directly after dilution with PBS; for coffee samples, a more complex method was used to remove the matrix
effect effectively. Membrane-based colloidal gold immunoassays had a visual detection limit of 1.0 ng mL−1 for OTA with a detection time of less than 10 min. For the validation of the cdELISA and membrane-based colloidal gold immunoassay,
samples were analyzed by high-performance liquid chromatography. The correlation between data obtained using the microwell
assay and HPLC was good (R
2 = 0.984). The developed immunoassay methods are suitable for the rapid quantitative or qualitative determination of OTA in
food samples. 相似文献
13.
To determine sulphamethazine (SMZ) residues in edible animal foods (pig muscle, chicken muscle, egg, fish, milk and liver),
a competitive direct enzyme-linked immunosorbent assay (ELISA) and a colloidal gold immunoassay were established. The limits
of detection of the ELISA and the colloidal gold immunoassay were 0.02 and 0.5 μg kg−1, respectively. The specificity of the ELISA developed to the SMZ was high according to the results of cross-reactivity testing
with 14 kinds of sulphonamides. To obtain a more sensitive immunoassay, buffer solution (30 mmol L−1 phosphate-buffered saline with 0.05% Tween 20, pH 8.5) was optimized through the whole test procedure. A simple and efficient
extraction method for the rapid detection of SMZ residues in foods was developed, with recoveries between 74 and 117.5%. Matrix
effects can be avoided by 1:10 dilution of pig muscle, chicken muscle, egg, fish, milk and liver with optimal buffer. The
detection limit of SMZ was 5 μg kg−1 in liver and 2 μg kg−1 in the other five samples. For the validation of the ELISA tests, sample extracts were analysed by ELISA and high-performance
liquid chromatography. The results obtained by these two methods showed a good correlation (r
2) which was greater than 0.9. The colloidal gold immunoassay presented in this assay was successfully applied to determine
SMZ in pig muscle, milk and fish below or equal to the maximum residue level (20 μg kg−1). 相似文献
14.
The fabrication and electrochemical characteristics of a penicillamine (PCA) self-assembled monolayer modified gold electrode
were investigated. The electrode can enhance the electrochemical response of uric acid (UA), and the electrochemical reaction
of UA on the PCA electrode has been studied by cyclic voltammetry and differential pulse voltammetry. Some electrochemical
parameters, such as diffusion coefficient, standard rate constant, electron transfer coefficient and proton transfer number
have been determined for the electrochemical behavior on the PCA self-assembled monolayer electrode. The electrode reaction
of UA is an irreversible process, which is controlled by the diffusion of UA with two electrons and two protons transfer at
the PCA/Au electrode. In phosphate buffer (pH 5.0), the peak current is proportional to the concentration of UA in the range
of 6.0 × 10−5–7.0 × 10−4 mol L−1 and 2.0 × 10−5–7.0 × 10−4 mol L−1 for the cyclic voltammetry and differential pulse voltammetry methods with the detection limits of 5.0 × 10−6 and 3.0 × 10−6 mol L−1, respectively. The method can be applied to determine UA concentration in real samples. 相似文献
15.
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
16.
M. Soledad García Joaquín Ortuño M. Isabel Albero María Cuartero 《Analytical and bioanalytical chemistry》2009,394(6):1563-1567
A trazodone-selective electrode for application in pharmaceutical quality control and urine analysis was developed. The electrode
is based on incorporation of a trazodone-tetraphenylborate ion exchanger in a poly(vinyl chloride) membrane. The electrode
showed a fast, stable and Nernstian response over a wide trazodone concentration range (5 × 10−5−1 × 10−2 M) with a mean slope of 59.3 ± 0.9 mV/dec of concentration, a mean detection limit of 1.8 × 10−5 ± 2.2 × 10−6 M, a wide working pH range (5–7.5) and a fast response time (less than 20 s). The electrode also showed good accuracy, repeatability,
reproducibility and selectivity with respect to some inorganic and organic compounds, including the main trazodone metabolite.
The electrode provided good analytical results in the determination of trazodone in pharmaceuticals and spiked urine samples;
no extraction steps were necessary. Dissolution testing of trazodone tablets, in different conditions of pH and particle size,
based on a direct potentiometric determination with the new selective electrode is presented as well. 相似文献
17.
Parviz Norouzi Mohammad Reza Ganjali Rassoul Dinarvand Mohammad Hasan Eshraghi Hassan Ali Zamani 《Russian Journal of Electrochemistry》2010,46(9):999-1006
The determination of prilocain, used to manage tonic-clonic seizures, has been carried out at micro gold electrode (Au UME)
using continuous fast Fourier transform square wave voltammetry. The Au UME electrode exhibited an effective response towards
prilocaine adsorption. The peak current was also found to be significantly increased. The determination was carried out in
phosphate containing electrolyte in the pH of 2.0 and a well-defined change on the peak current were noticed. The peak current
was found to be linearly dependent on concentration of prilocain in the concentration range 5.0 × 10−7–1.0 × 10−11 M with a detection limit of 5.0 × 10−12 M. This paper describes development of a new analysis system to determine of prilocain by a novel square wave voltammetry
method to perform a very sensitive method. The method used for determination of prilocain by measuring the changes in admittance
voltammogram of a gold ultramicroelectrode (in 0.05 M H3PO4 solution) caused by adsorption of the prilocain on the electrode surface. Variation of admittance in the detection process
is created by inhibition of oxidation reaction of the electrode surface, by adsorbed of prilocain. Furthermore, signal-to-noise
ratio has significantly increased by application of discrete Fast Fourier Transform (FFT) method, background subtraction and
two-dimensional integration of the electrode response over a selected potential range and time window. Also in this work some
parameters such as SW frequency, eluent pH, and accumulation time were optimized. The relative standard deviation at concentration
5.0 × 10−8 M is 5.8% for 5 reported measurements. 相似文献
18.
Summary A capillary electrophoretic method for the determination of Cu(II) and Co(III) chelates with ethylenediamine in electroless
copper plating baths has been developed. The influence of carrier electrolyte parameters such as nature of counter-ion and
pH were studied and discussed. The optimised separations were carried out in a fused silica capillary (57 cm × 75 μm I.D.)
filled with an ethylenediamine sulfate electrolyte (20 mol L−1 ethylendiamine, pH7.0 with H2SO4; applied voltage, +25 kV) using direct UV detection at 214 nm. The detection limits for a signalto-noise ratio of 3 and 10s
hydrodynamic injection were 5×10−6 mol L−1 for Cu(II) and 1×10−6 mol L−1 for Co(III). The relative standard deviations of the peak areas for Cu(II) and Co(III) were found to be 1.5% and 2.4%, respectively,
with five consecutive injections of standard solution containing 5×10−5 mol L−1 of each metal ion. Application of the method to the speciation of Cu(II) and Co(III) complexes in copper plating bath samples
is also demonstrated. 相似文献
19.
Acetylcholinesterase-based biosensors for quantification of carbofuran, carbaryl, methylparaoxon, and dichlorvos in 5% acetonitrile 总被引:1,自引:0,他引:1
Valdés-Ramírez G Cortina M Ramírez-Silva MT Marty JL 《Analytical and bioanalytical chemistry》2008,392(4):699-707
Amperometric acetylcholinesterase biosensors have been developed for quantification of the pesticides carbofuran, carbaryl,
methylparaoxon, and dichlorvos in phosphate buffer containing 5% acetonitrile. Three different biosensors were built using
three different acetylcholinesterase (AChE) enzymes—AChE from electric eel, and genetically engineered (B394) and wild-type
(B1) AChE from Drosophila melanogaster. Enzymes were immobilized on cobalt(II) phthalocyanine-modified electrodes by entrapment in a photocrosslinkable polymer
(PVA-AWP). Each biosensor was tested against the four pesticides. Good operational stability, immobilisation reproducibility,
and storage stability were obtained for each biosensor. The best detection limits were obtained with the B394 enzyme for dichlorvos
and methylparaoxon (9.6 × 10−11 and 2.7 × 10−9 mol L−1, respectively), the B1 enzyme for carbofuran (4.5 × 10−9 mol L−1), and both the B1 enzyme and the AChE from electric eel for carbaryl (1.6 × 10−7 mol L−1). Finally, the biosensors were used for the direct detection of the pesticides in spiked apple samples. 相似文献
20.
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