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1.
Zhang De-qiang Ni Zhe-ming Sun Han-wen 《Fresenius' Journal of Analytical Chemistry》1997,358(5):641-645
Parts-per-billion levels of germanium can be determined directly by graphite furnace atomic absorption spectrometry (GFAAS)
using palladium plus strontium as a mixed modifier resulting in pyrolysis temperatures up to 1400 °C without loss of germanium.
At this temperature the matrix effect including the most troublesome sulfate interference can be eliminated. Palladium plus
strontium nitrate is advantageous compared to palladium alone or palladium plus magnesium nitrate; an amount of 15 μg of sulfate
does not show any interference on the determination of 1 ng of germanium. The method was successfully applied to the determination
of ng/g levels of germanium in botanical samples and coal fly ash after thermal decomposition of the samples in a mixture
of acids using a pressure bomb. The results were consistent with the reference values given for botanical samples and coal
fly ash with a recovery range of 96.4∼103.4%
Received: 16 September 1996/Revised: 10 December 1996/Accepted: 14 January 1997 相似文献
2.
Sharma S Vandana Ghoshal SK Arora P Dilbaghi N Chaudhury A 《Applied biochemistry and biotechnology》2009,159(2):310-316
In the present frame of work, Macrophomina phaseolina is encapsulated in silica matrices at various concentrations by low temperature sol-gel technique using tetraethylorthosilicate
(TEOS) as precursor. The optical and photophysical properties of these samples have been studied by second harmonics of Nd:YAG
laser at 532 nm. UV-visible absorption spectra of samples have been recorded and it is found that the absorption increases
with increase in concentration of fungus. Further, a decrease in output transmission intensity of the laser has been observed
with increase in fungus concentration. The temporal response of these samples has also been examined. The results show that
the fungus concentration can be measured within ∼15–20 min. This method of optical sensing of fungus in test sample is faster
than other techniques, such as the conventional colorimetric method which takes about 1 h. 相似文献
3.
Ralf Eiden Ralf Falter Barbara Augustin-Castro Heinz Friedrich Sch?ler 《Fresenius' Journal of Analytical Chemistry》1997,357(4):439-441
Distillation as a way of sample digestion has been combined with on-line RP C18 preconcentration and HPLC-UV-PCO-CVAAS (high
performance liquid chromatography — ultra violet — post column oxidation — cold vapour atomic absorption spectrometry) for
the determination of methylmercury at back-ground levels in sediments, soils and fish tissue. To prove the accuracy of this
method, it was applied to sediment and fish tissue reference materials. The results correspond with the reference values within
their error ranges. Excellent recoveries (92–95%) were obtained for the sediment samples by means of the standard addition
method. The standard deviations of the sediment samples were within an acceptable range (7.2–12.5%), those of the fish samples
were substantially lower (3.4–5.0%). The detection limit is 0.04 ng/g for 1 g sample weight. 相似文献
4.
The vaporization of sulfur containing samples in graphite vaporizers for atomic absorption spectrometry is accompanied by modification of sulfur by carbon and, respectively, appearance at high temperature of structured molecular absorption in 200-210 nm wavelength range. It has been proposed to employ the spectrum for direct determination of sulfur in coal; soundness of the suggestion is evaluated by analysis of coal slurry using low resolution CCD spectrometer with continuum light source coupled to platform or filter furnace vaporizers. For coal in platform furnace losses of the analyte at low temperature and strong spectral background from the coal matrix hinder the determination. Both negative effects are significantly reduced in filter furnace, in which sample vapor efficiently interacts with carbon when transferred through the heated graphite filter. The method is verified by analysis of coals with sulfur content within 0.13-1.5% (m/m) range. The use of coal certified reference material for sulfur analyte addition to coal slurry permitted determination with random error 5-12%. Absolute and relative detection limits for sulfur in coal are 0.16 μg and 0.02 mass%, respectively. 相似文献
5.
The technique of gamma-ray analysis of light elements (GRALE) is extended to measure the concentration of carbon, nitrogen,
oxygen, sulfur and silicon in coal samples. The composition of the sample is determined by analyzing the spectrum of gamma
rays emitted following inelastic scattering of protons bombarding the target. A large volume lithium drifted germanium detector
is used as a gamma-ray detector in this work. Coal samples are irradiated with 9.5 MeV protons in a helium atmosphere for
1000 sec. Results with standard coal samples indicate that the method has an accuracy of ∼5% of the concentration of each
element and a precision of ∼4% for elements constituting at least 1% of the coal by weight. 相似文献
6.
M. D. Lechner Helmut Cölfen Vikas Mittal Antje Völkel Wendel Wohlleben 《Colloid and polymer science》2011,289(10):1145-1155
Analytical ultracentrifugation is one of the most powerful methods for the characterization of nanoparticles since the days
of its invention due to its high resolution and statistical significance. Latexes with different sizes and their mixtures
have been measured by sedimentation with the analytical ultracentrifuge (AUC) OPTIMA XL-I (Beckman Coulter, Palo Alto, CA,
USA) with interference optics at λ
0 = 675 nm and absorption optics at λ
0 = 546 and 263 nm. Additionally, a blue pigment with high absorption characteristic at visible light has been investigated.
A large influence of Mie scattering and Mie absorption on the particle size distribution with respect to absorption optics
and samples with moderate or broad size distribution is observed. Therefore, the consideration of the Mie scattering effect
is compulsory for most AUC measurements of nanoparticles with absorption optics. 相似文献
7.
In this paper, a novel method has been established to determine tiopronin using potassium ferricyanide as spectroscopic probe
reagent. It has been demonstrated that Fe(III) is reduced to Fe(II) by tiopronin, and the in situ formed Fe(II) reacts with
potassium ferricyanide to form soluble Prussian blue. Beer’s law is obeyed in the range of tiopronin concentration of 0.040–9.00
μg/mL at the maximal absorption wavelength of 735 nm. The linear regression equation is A = 0.0153 + 0.1605c (μg/mL) with a correlation coefficient of 0.9997 and the apparent molar absorption coefficient of 2.6 × 104 L/mol cm. The detection limit is 0.030 μg/mL and RSD is 1.3%. The parameters with regard to determination have been optimized
and the reaction mechanism has been discussed. This method has been successfully applied to determine tiopronin in pharmaceutical
and urine samples with satisfactory results. 相似文献
8.
Ralf Eiden Ralf Falter Barbara Augustin-Castro Heinz Friedrich Schöler 《Analytical and bioanalytical chemistry》1997,357(4):439-441
Distillation as a way of sample digestion has been combined with on-line RP C18 preconcentration and HPLC-UV-PCO-CVAAS (high
performance liquid chromatography – ultra violet – post column oxidation – cold vapour atomic absorption spectrometry) for
the determination of methylmercury at background levels in sediments, soils and fish tissue. To prove the accuracy of this
method, it was applied to sediment and fish tissue reference materials. The results correspond with the reference values within
their error ranges. Excellent recoveries (92–95%) were obtained for the sediment samples by means of the standard addition
method. The standard deviations of the sediment samples were within an acceptable range (7.2–12.5%), those of the fish samples
were substantially lower (3.4–5.0%). The detection limit is 0.04 ng/g for 1 g sample weight.
Received: 23 November 1995/Revised: 16 April 1996/Accepted: 20 April 1996 相似文献
9.
Zhang De-qiang Yang Li-li Sun Jian-min Sun Han-wen 《Analytical and bioanalytical chemistry》1999,363(4):359-363
A method has been proposed for the determination of mercury by cold vapor generation graphite furnace atomic absorption spectrometry
(CV-GFAAS) with Pd-Rh as coating and chemical modifier. The trapping efficiency for mercury with Pd-Rh was higher than with
Pd alone. The characteristic mass of the method, which gives an integrated absorbance of 0.0044 s, was found to be 55 pg and
the absolute detection limit (3 σ) of 37 pg was obtained with the proposed modifier. The method was successfully applied to
the determination of mercury in standard reference water samples, wastewater samples and cosmetics with a recovery range of
95–104%.
Received: 10 April 1998 / Revised: 20 August 1998 / Accepted: 23 September 1998 相似文献
10.
Zhang De-qiang Yang Li-li Sun Jian-min Sun Han-wen 《Fresenius' Journal of Analytical Chemistry》1999,363(4):359-363
A method has been proposed for the determination of mercury by cold vapor generation graphite furnace atomic absorption spectrometry
(CV-GFAAS) with Pd-Rh as coating and chemical modifier. The trapping efficiency for mercury with Pd-Rh was higher than with
Pd alone. The characteristic mass of the method, which gives an integrated absorbance of 0.0044 s, was found to be 55 pg and
the absolute detection limit (3 σ) of 37 pg was obtained with the proposed modifier. The method was successfully applied to
the determination of mercury in standard reference water samples, wastewater samples and cosmetics with a recovery range of
95–104%.
Received: 10 April 1998 / Revised: 20 August 1998 / Accepted: 23 September 1998 相似文献
11.
?zlem Aksu D?nmez Abdürrezzak Bozdo?an G?nül Kunt 《Monatshefte für Chemie / Chemical Monthly》2006,35(6):1163-1168
A partial least-squares calibration (PLS) method has been developed for simultaneous quantitative determination of escin (ES) and diethylamine salicylate (DAS) in pharmaceutical preparations. The resolution of these mixtures has been accomplished without prior separation or derivatisation,
by using partial least-squares (PLS-2) regression analysis of electronic absorption spectral data. The experimental calibration
matrix was constructed with 9 samples. The concentration ranges considered were 10, 20, 30 (ES) and 40, 50, 60 (DAS) μg cm−3. The absorbances were recorded between 200 and 325 nm every 5 nm. Proposed method was compared with conventional spectrophotometric
method. The results show that PLS-2 is a simple, rapid, and accurate method applied to the determination of these compounds
in pharmaceuticals. 相似文献
12.
Özlem Aksu Dönmez Abdürrezzak Bozdoğan Gönül Kunt 《Monatshefte für Chemie / Chemical Monthly》2006,137(9):1163-1168
Summary. A partial least-squares calibration (PLS) method has been developed for simultaneous quantitative determination of escin (ES) and diethylamine salicylate (DAS) in pharmaceutical preparations. The resolution of these mixtures has been accomplished without prior separation or derivatisation,
by using partial least-squares (PLS-2) regression analysis of electronic absorption spectral data. The experimental calibration
matrix was constructed with 9 samples. The concentration ranges considered were 10, 20, 30 (ES) and 40, 50, 60 (DAS) μg cm−3. The absorbances were recorded between 200 and 325 nm every 5 nm. Proposed method was compared with conventional spectrophotometric
method. The results show that PLS-2 is a simple, rapid, and accurate method applied to the determination of these compounds
in pharmaceuticals. 相似文献
13.
A new Schiff base, N,N′-bis-(2-hydroxy-5-bromobenzyl)-2-hydroxy-1,3-diiminopropane, has been synthesized for the very sensitive
determination of iron(III) and iron(II) in natural water samples. It enabled a very selective and rapid method for iron determination
to be developed. The method has also been applied to total iron determination in sediment samples. In the preconcentration
system, the Schiff base reagent is mixed with the samples and chelates containing iron(III). The complexes are then adsorbed
on silica gel within a column system. Elution of the adsorbed chelate from the silica gel was performed with a small volume
of acetone containing 2.5% nitric acid. The iron is measured off-line by flame atomic absorption spectrometry. The method
can be applied to the preconcentration, separation and speciation of iron. The effects of parameters such as pH, sample flow
rate, eluent flow rate, foreign ions and ligand concentration have been investigated. The effect of humic acid that can produce
complexes with metal ions in natural systems has also been investigated. The results obtained indicate that the method is
not affected by the presence of up to 10 ppm humic acid, which would be a very high concentration to be present in natural
systems. The solid phase extraction method developed has been applied to the determination of iron in both natural water samples
and sediment samples. The LOD was found to be 0.17 mg L−1 when no preconcentration was used, although preconcentration factors of 100 could be achieved. The recovery values for spiked
samples were between 100 and 104%. The results were compared statistically with those from the standard 1,10 phenanthroline
method used for iron speciation in water systems. A Student’s t-test indicated no significant difference between the two methods. In addition, this method was applied to the analysis of
a certified sediment sample, LGC 6156. Generally, a 10-fold preconcentration factor was required for the analysis of natural
water samples. 相似文献
14.
Domínguez-Lledó FC Galindo-Riaño MD Díaz-López IC García-Vargas M Granado-Castro MD 《Analytical and bioanalytical chemistry》2007,389(2):653-659
In this work, a bulk liquid membrane method has been applied for Ni enrichment and separation from natural waters. The carrier-mediated
transport was accomplished by pyridine-2-acetaldehyde benzoylhydrazone dissolved in toluene as a complexing agent. The preconcentration
was achieved through pH control of source and receiving solutions via a counterflow of protons. The main variables were optimized
by using a modified simplex technique. High transport efficiencies (101.2 ± 1.8–99.7 ± 4.2%) were provided by the carrier
for nickel ions in a receiving phase of 0.31 mol L−1 nitric acid after 9–13 h depending on sample salinity. The precision of the method was 2.05% (without a saline matrix) and
4.04% (with 40 g L−1 NaCl) at the 95% confidence level and the detection limit of the blank was 0.015 μg L−1 Ni for detection by atomic absorption spectroscopy. The applicability of the method was tested on certified reference and
real water samples with successful results, even for saline samples. The relative errors were −0.60% for certified reference
materials and ranged from −0.39 to 2.90% and from 0.3 to 11.05% for real samples, obtained by comparison of inductively coupled
plasma mass spectrometry and adsorptive cathodic stripping voltammetry measurements, respectively. 相似文献
15.
Dimosthenis L. Giokas Evangelos K. Paleologos Panayotis G. Veltsistas Miltiades I. Karayannis 《Mikrochimica acta》2002,140(1-2):81-86
A simple spectrophotometric method for the determination of copper is described herewith, based on the formation of colored
species of Cu (II) with 5-mercapto-3-phenyl-1,3,4-thiadiazole-2-thione (Bismuthiol II) in the presence of a neutral surfactant,
Triton X-114. The yellow colored complex of Cu (II)–Bismuthiol-II–Triton X-114 shows maximum absorbance at 395 nm in water.
The detection limit of the method is 0.03 mg/l while the Beer’s law is obeyed up to 1.2 mg/l of the analyte in an aqueous
medium. The validity of the method has been examined for the determination of copper in wines, food supplements and raisins.
The results obtained were in good agreement with those obtained using flame atomic absorption spectrometry (FAAS). The method
thus constitutes a handy alternative for the determination of copper (II) in nutritional samples.
Received May 16, 2001; accepted December 10, 2001; published online June 24, 2002 相似文献
16.
Javier Galbán Vanesa Sanz Susana de Marcos 《Analytical and bioanalytical chemistry》2010,398(5):2117-2124
Peracetic acid (PAA) is selectively determined in the presence of hydrogen peroxide (H2O2) by using the self-indicating UV–Vis molecular absorption properties of catalase. The PAA reacts with the protein giving
an intermediate (Cat-I) which is reduced back by the aminoacid core surrounding the hemegroup. Since the original form of
the enzyme and the Cat-I have different UV–Vis absorption properties, the absorbance changes can be used for PAA determination.
The H2O2/catalase reaction is extremely fast so that neither Cat-I compound nor kinetic interferences are observed. The method permits
PAA determination in the 5 × 10−7 to 1.5 × 10−5 M range, the reproducibility being between 1% and 10%. Using this method, PAA has been successfully determined in water samples
treated with commercial PAA/H2O2 biocides. A theoretical study has also been carried out for obtaining a mathematical model able to analytically describe
the process. 相似文献
17.
Summary GC-MS analysis of hydrocarbons, thermally mobilized from rock and coal samples (“thermodesorption”) at 320°C, provides valuable
and readily available information of organic geochemical significance. Two oil shale and three coal samples of different rank
have been selected for this study. The molecular patterns of compound classes of various saturated and aromatic hydrocarbons
are recorded here by employing mass chromatography of selected ions. The method described is of particular importance for
the detection of those volatile constituents in coals and sedimentary rocks, which are usually not recovered during elaborate
workup procedures (i.e. solvent extraction, liquid chromatography) due to evaporation losses. 相似文献
18.
Citric acid was thermochemically esterified onto defatted cotton fibre to produce a carboxyl cotton chelator (CCC), which
had been used for extraction of copper prior to its determination by flame atomic absorption spectrometry. The extraction
of copper has been studied under both batch and column methods. Quantitative extraction of copper was achieved in the pH range
4–7. The time needed to extract each sample was less than 30 min by the batch method. The copper extraction capacity of CCC
was found to be 22.7 mg g−1 at optimal pH value. The elution was quantitative with 1 mol L−1 hydrochloric acid. The feasible flow rate of copper-containing solution for quantitative extraction onto the column packed
with CCC was 0.5–4.0 mL min−1, whereas for elution it was less than 1.5 mL min−1. A 100-fold extraction factor could be achieved under the optimal column conditions. The tolerance limits for common metal
ions on the extraction of copper and the time of column reuse were investigated. The proposed method has been successfully
applied for extraction and determination of copper in industrial wastewater and natural water samples. 相似文献
19.
Elena Belluso Donata Bellis Elisa Fornero Silvana Capella Giovanni Ferraris Sergio Coverlizza 《Mikrochimica acta》2006,154(1-2):95-100
A method based on cloud point extraction (CPE) separation/preconcentration of trace cadmium as a prior step to its determination
by graphite furnace atomic absorption spectrometry (GFAAS) has been developed. If the system temperature is higher than the
cloud point temperature (CPT) of the nonionic surfactant of p-octyl polyethyleneglycolphenyether (Triton X-100), the complex
of Cd2+ with 1-(2-pyridylazo)-2-naphthol (PAN) could be extracted into surfactant-rich phase. The chemical variables affecting CPE
were evaluated and optimized. Under the optimum conditions, preconcentrating 10.0 mL of water samples permitted a limit of
detection of 5.9 ng · L−1 (3σ) for cadmium with an enhancement factor of 50 and a relative standard deviation of 2.1% (n = 11, c = 2.0 ng · mL−1). The method was applied to the determination of cadmium in reference material and water samples with satisfactory results. 相似文献
20.
铕-结晶紫缔合物分光光度法测定痕量铕 总被引:1,自引:0,他引:1
在碱性(pH10.10)条件下,铕(Ⅲ)与结晶紫形成缔合物,表观摩尔系数为=1.8×105L/(mol.cm),铕的浓度在0.15~1.2mg/l范围内遵守比耳定律,组成摩尔比为Eu∶CV=1∶2. 相似文献