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1.
The problem with toxic metal ion determination in blood is the adsorption of organic compounds on the electrode surface and the formation of complexes between metal ions and organic constituents of blood. This is the reason why usually preliminary acid digestion or other sample pretreatment is used. Two kinds of electrodes have been used: “Ultra-Trace Electrode”, made from impregnated graphite (I), and thick film graphite disposable electrodes (II). The analysis of whole blood with different sample preparation methods shows, that chemical digestion is not necessary for the analysis. Electrochemical two-stage sample preparation provides the possibility for analysing whole blood with the mentioned electrodes. Thick film disposable electrodes are less sensitive to the interference of organic constituents of blood. These electrodes give the possibility to determine total cadmium, lead and copper concentration in whole blood without special sample pretreatment. The application of “Ultra-Trace Electrode” for blood analysis is possible only after preliminary pretreatment of blood by chemical digestion or electrochemical sample preparation. 相似文献
2.
An anodic stripping voltammetric method has been developed for determination of cadmium, lead, copper and zinc in acetic acid extract of glazed ceramic surfaces. An aliquot of 4% (v/v) acetic acid solution was kept in a ceramic ware for 24 h in the dark, then 10 mL of the extracted solution was placed in a voltammetric cell. The solution was purged with oxygen free nitrogen gas for 3 min before deposition of the metals was carried out by applying a constant potential of −1.20 V versus Ag/AgCl to the hanging mercury drop electrode (HMDE) for 45 s. A square wave waveform was scanned from −1.20 to 0.15 V and a voltammogram was recorded. A standard addition procedure was used for quantification. Detection limits of 0.25, 0.07, 2.7 and 0.5 μg L−1 for cadmium, lead copper and zinc, respectively, were obtained. Relative standard deviations for 11 replicate determinations of 100 μg L−1 each of all the metals were in the range of 2.8-3.6%. Percentage recoveries obtained by spiking 50 μg L−1 of each metal to the sample solution were in the range of 105-113%. The method was successfully applied to ceramic wares producing in Lampang province of Thailand. It was found that the contents of cadmium, lead, copper and zinc released from the samples were in the range of <0.01-0.16, 0.02-0.45, <0.14 and 0.28-10.36 μg dm−2, respectively, which are lower than the regulated values of the Thai industrial standard. The proposed method is simpler, more convenient and more sensitive than the standard method based on FAAS. 相似文献
3.
An evaluation of the non-boiling evaporation technique for the preconcentration of Pb, Cd, Cu, Zn at the pg g?1 level in water samples is presented. Various improvements were made to allow efficient control of contamination problems at these extremely low concentrations. They include the choice of FEP Teflon for the evaporation containers and the use of sophisticated cleaning, ageing and pre-conditionning procedures. Detailed calibration graphs were obtained down to the sub-pg g?1 level by processing ultra-low concentration standards. This technique was then applied to the determination of these four metals in snow samples collected in Greenland and Antarctica. 相似文献
4.
Luiz Frederico Rodrigues Julio Cezar Paz de Mattos Valderi Luiz Dressler Dirce Pozebon Érico Marlon de Moraes Flores 《Spectrochimica Acta Part B: Atomic Spectroscopy》2007
Trace impurities of Cd, Cu and Pb were determined in alumina based catalysts using direct solid sampling graphite furnace atomic absorption spectrometry (DSS-GF AAS). The analyzed catalysts are widely used in petrochemical processes. The following analytical parameters were evaluated: pyrolysis and atomization temperatures, feasibility of calibration with aqueous solutions, the necessity for palladium as chemical modifier and the sample mass introduced into the atomizer. Test samples between 0.05 and 8.5 mg were used. Palladium was investigated as chemical modifier but no improvement in analytical performance was obtained and its use was considered unnecessary for all elements. The results obtained by DSS-GF AAS were compared with those of inductively coupled plasma optical emission spectrometry (ICP OES) and also with conventional solution analysis by GF AAS (Sol-GF AAS). Characteristic masses were 1.4, 9 and 20 pg, for Cd, Cu and Pb, respectively. Using DSS-GF AAS the relative standard deviation was always less than 10% and the results agreed with those obtained by Sol-GF AAS and ICP OES. Calibration using aqueous solutions showed good linearity within the working range (R2 better than 0.99). Limits of detection (3σ, n = 10) for Cd, Cu and Pb using the proposed procedure were 0.2, 22, and 1.2 ng g− 1, respectively. 相似文献
5.
Using octadecyl functional groups (C18) bonded to silica gel as sorbent and methanol as eluent, the flow injection sorbent extraction features of dialkyldithiophosphates (RO)2P(S)S− as the chelating agent for cadmium, copper and lead was investigated in respect of the effects of pH, alkyl substituent group, reagent concentration and masking agent, with flame atomic absorption spectrometric detection. The elements are quantitatively extracted with the short-alkyl-chain reagents (R up to propyl) in acidic medium. The extractability decreases with the number of carbon atoms in the alkyl groups of the reagents and with the reagent concentration when the alkyl groups are larger than butyl, but masking agents increase the extractability. An explanation proposed for this effect is the formation of polynuclear chelates. Diethyldithiophosphate can be used for the selective determination of cadmium, copper and lead in digested solid environmental samples. With 20 s sample loading at 8.7 ml min−1, the enhancement factors are 35 for cadmium and copper or 26 for lead; the detection limits (3σ) are 0.8, 1.4 and 10.0 μg 1−1 for cadmium, copper and lead, respectively. 相似文献
6.
I. Papadakis Christophe R. Quétel Philip D. P. Taylor Paul De Bièvre 《Accreditation and quality assurance》2000,5(5):198-204
Metrological certification through a primary method of measurement and how it can be achieved is demonstrated in this paper,
using the example of re-certification of cadmium and lead content in a biological material, the Bureau Communataire de Reference,
reference material CRM-278R mussel tissue. The measurement method used was isotope dilution in combination with inductively
coupled plasma mass spectrometry. Microwave digestion was applied to the samples prior to the measurements. A detailed uncertainty
budget was evaluated according to the International Organisation of Standardisation, Guide to the Expression of Uncertainty
and EURACHEM Guide, resulting in an expanded uncertainty.
Received: 20 August 1999 / Accepted: 3 January 2000 相似文献
7.
Introducing the concept of uncertainty of measurement in testing in association with the application of the standard ISO/IEC 17025 总被引:1,自引:0,他引:1
N. Mueller 《Accreditation and quality assurance》2002,7(2):79-80
ISO/IEC 17025 requests laboratories to estimate the overall uncertainty associated with a test result. In many cases this
means a new requirement to laboratories. It is essential to understand the importance of the knowledge of the uncertainty
of measurements as well as the principle that not always the smallest possible uncertainty is needed, but fitness for purpose
has to be achieved. The paper suggests a policy on the implementation of the concept of uncertainty and guidance on how to
proceed, taking into account the present state of the art of understanding the problem. 相似文献
8.
Preparation of silicon-doped ferrihydrite for adsorption of lead and cadmium: Property and mechanism
《中国化学快报》2021,32(10):3169-3174
In this study, Si-doped ferrihydrite (Si-Fh) was successfully synthesized by a simple coprecipitation method for removal of heavy metals in water. Subsequently, the physicochemical properties of Si-Fh before and after adsorption were further studied using several techniques. The Si-Fh exhibited good adsorption capacity for heavy metal ions such as Pb(II) and Cd(II). The maximum adsorption capacities of lead and cadmium are respectively 105.807, 37.986 mg/g. The distribution coefficients of the materials for Pb(II) and Cd(II) also showed a great affinity (under optimal conditions). Moreover, it was found that the adsorption fit well with the Freundlich isotherm and pseudo-second-order kinetic model which means this was a chemical adsorption process. It can be conducted from both characterization and model results that adsorption of Pb(II) and Cd(II) was mainly through the complexation interaction of abundance oxygen functional groups on the surface of Si-Fh. Overall, the Si-Fh adsorbents with many superiorities have potential for future applications in the removal of Pb(II) and Cd(II) from wastewater. 相似文献
9.
The preparation and analysis of the oxygen mass fraction of three pure copper reference materials (BAM-379/1, BAM-379/2, BAM-379/3)
intended for the calibration of spark emission spectrometry are described here. Data of homogeneity testing and round robin
certification in collaboration with 12 independent laboratories from metalworking industry and research are reported. Problems
with the establishment of traceability in this special case are discussed.
Received: 20 July 2001 Accepted: 13 October 2001 相似文献
10.
Keith Jewell 《Accreditation and quality assurance》2001,6(4-5):154-159
The author considers the fundamental differences between analyses in microbiology and those in chemistry and physics, deducing
special issues for microbiological proficiency testing. He concludes that the variability and uncertainty implicit in microbiological
analysis requires a broader range of proficiency scheme providers providing a broader range of services than in chemistry
and physics.
Received: 10 November 2000 Accepted: 3 December 2000 相似文献
11.
A method for the accurate determination of Cd and Pb isotope compositions in sediment samples is presented. Separation of Cd and Pb was designed by using an anionic exchange chromatographic procedure. Measurements of Cd isotopic compositions were carried out by multi-collector inductively coupled plasma mass spectrometer (MC-ICPMS), by using standard-sample bracketing technology for mass bias correction and Pb isotopic ratios were determined by thermal ionization mass spectrometry (TIMS). The factors that affect the accurate and precise Cd isotope compositions analysis, such as instrumental mass fractionation and isobaric interferences, were carefully evaluated and corrected. The Cd isotopic results were reported relative to an internal Cd solution and expressed as the δ114/110Cd. Five Cd reference solutions and one Pb standard were repeatedly measured in order to assess the accuracy of the measurements. Uncertainties obtained were estimated to be lesser than 0.11‰ (2s) for the δ114/110Cd value. Analytical uncertainties in 2s for Pb isotopic ratios were better than 0.5‰. The method has been successfully applied to the investigation of Cd and Pb isotope compositions in sediment samples collected from North River in south China. 相似文献
12.
High-sensitivity determination of lead and cadmium based on the Nafion-graphene composite film 总被引:1,自引:0,他引:1
Graphene nanosheets, dispersed in Nafion (Nafion-G) solution, were used in combination with in situ plated bismuth film electrode for fabricating the enhanced electrochemical sensing platform to determine the lead (Pb2+) and cadmium (Cd2+) by differential pulse anodic stripping voltammetry (DPASV). The electrochemical properties of the composite film modified glassy carbon electrode were investigated. It is found that the prepared Nafion-G composite film not only exhibited improved sensitivity for the metal ion detections, but also alleviated the interferences due to the synergistic effect of graphene nanosheets and Nafion. The linear calibration curves ranged from 0.5 μg L−1 to 50 μg L−1 for Pb2+ and 1.5 μg L−1 to 30 μg L−1 for Cd2+, respectively. The detection limits (S/N = 3) were estimated to be around 0.02 μg L−1 for Pb2+ and Cd2+. The practical application of the proposed method was verified in the water sample determination. 相似文献
13.
In the present paper, a simultaneous pre-concentration procedure for the sequential determination of cadmium and lead in table salt samples using flame atomic absorption spectrometry is proposed. This method is based on the liquid-liquid extraction of cadmium(II) and lead(II) ions as dithizone complexes and direct aspiration of the organic phase for the spectrometer. The sequential determination of cadmium and lead is possible using a computer program. The optimization step was performed by a two-level fractional factorial design involving the variables: pH, dithizone mass, shaking time after addition of dithizone and shaking time after addition of solvent. In the studied levels these variables are not significant. The experimental conditions established propose a sample volume of 250 mL and the extraction process using 4.0 mL of methyl isobutyl ketone. This way, the procedure allows determination of cadmium and lead in table salt samples with a pre-concentration factor higher than 80, and detection limits of 0.3 ng g−1 for cadmium and 4.2 ng g−1 for lead. The precision expressed as relative standard deviation (n = 10) were 5.6 and 2.6% for cadmium concentration of 2 and 20 ng g−1, respectively, and of 3.2 and 1.1% for lead concentration of 20 and 200 ng g−1, respectively. Recoveries of cadmium and lead in several samples, measured by standard addition technique, proved also that this procedure is not affected by the matrix and can be applied satisfactorily for the determination of cadmium and lead in saline samples. The method was applied for the evaluation of the concentration of cadmium and lead in table salt samples consumed in Salvador City, Bahia, Brazil. 相似文献
14.
The nucleation process of Pb and Cu onto indium-tin oxide electrodes was studied by single potentiostatic steps using 0.1×10–4 mol L–1 Cu(NO3)2 and 2×10–2 mol L–1 Pb(NO3)2 solutions in aqueous 1.0 mol L–1 NaNO3. The current, Imax, and the time, tmax, corresponding to the maximum, were evaluated by 3D nucleation with a diffusion-controlled growth model for instantaneous and progressive nucleation. The non-dimensional plots of (I/Imax)2 vs. t/tmax showed that Cu and Pb nucleation closely followed the response predicted for instantaneous nucleation. Other parameters, such as I vs. t1/2 and I2maxtmax, as well as nuclei micrographs, were analyzed, corroborating the results obtained. 相似文献
15.
J. Forstén 《Accreditation and quality assurance》1998,3(7):285-288
This article mainly focuses on the testing of products, materials, etc., but the general principles are applicable in a broader
perspective. Quality of testing should be judged based on fitness for purpose. This judgement includes both objective and
subjective elements. The possibility to make decisions and other professional judgements based on test results alone is discussed
and compared with the decisions and judgements being made through the certification and inspection process. Quality, including
the uncertainty of the test results, depends on many factors, and in order to make necessary improvements in the testing procedures
based on the customers' needs, the right issues should be addressed. The question arises as to whether, in laboratories' quality
systems and in the accreditation and certification process, attention is really paid to those factors that are crucial to
obtaining reliable results. 相似文献
16.
17.
《Journal of Coordination Chemistry》2012,65(3):459-472
A new tridentate ligand 2-((quinolin-8-yloxy)methyl)benzimidazole (L) and three coordination compounds, [CuLCl2] (1), [CuL(H2O)(SO4)?· 2H2O] n (2), and {[Cd2L2Cl4][CdLCl2(H2O)]2}?·?H2O (3), have been synthesized and characterized. Single crystal structure analyses reveal extensive intermolecular hydrogen bonding, resulting in generation of 1-D–3-D supramolecular networks. Compounds 1 and 2 constitute the first examples of Cu complexes containing both 8-hydroxyquinoline and benzimidazole, while 3 represents the first Cd complex bearing this ligand. Complexes 1–3 show similar quasi-reversible electrochemical behaviors. Complex 2 exhibits a predominantly ferromagnetic interaction between copper centers, and 3 has good fluorescence and can be used as an optical material. 相似文献
18.
Oto Mestek Kateřina Mališová Richard Koplík Jan Polák Miloslav Suchánek 《Accreditation and quality assurance》2008,13(6):305-310
The postulated uncertainty of many commercially available standard solutions is estimated on the basis of uncertainties of
individual preparation steps. The declared concentration of Cu standard solution (1000 ± 2) mg/L was verified by gravimetric
analysis (found (1000.7 ± 0.4) mg/L), isotope dilution with commercial and laboratory-prepared isotope-enriched solutions
(found (1000.6 ± 16.8) mg/L and (1002.4 ± 3.6) mg/L, respectively), and by atomic absorption spectrometry (found (1001.4 ± 5.3)
mg/L). Uncertainty budgets of all used methods are given and the procedures of uncertainty estimation are fully documented. 相似文献
19.
M. Golze 《Accreditation and quality assurance》1998,3(6):227-230
The general requirement of Quality Management standards to include in test reports a statement of the uncertainty of the
results reflects the fact that a test result is rather useless without a knowledge of its accuracy. After an outline of the
basic concepts of uncertainty, the need for uncertainty statements is illustrated for different ranges of applications.
Received: 23 December 1997 · Accepted: 3 March 1998 相似文献
20.
S. S. Tahir Rauf Naseem Anwar ul Haq Khalid Saeed 《Accreditation and quality assurance》2005,10(7):362-368
This inter-laboratory comparison study was arranged for 28 laboratories from different public and private sector organizations
in Pakistan having wastewater testing capabilities aimed at improving the quality and comparability of test results. This
national inter-laboratory study was started in December 2003 and completed in July 2004. Laboratories were invited to analyze
the wastewater collected from printed circuit board (PCB) industry for lead and copper contamination. The samples fulfill
the criteria for homogeneity and stability as done by the reference laboratory. The results obtained from participating laboratories
were analyzed in terms of Hampel Test for outliers, while the performance evaluation of the participating laboratories was
done on the basis of Z-score. An assigned value derived from the participant's results was compared with a reference value provided by a reference
laboratory. Overall >50% of the participating laboratories have shown good performance in this PT-program 相似文献