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1.
Eduardo de Almeida Paulo Rogério Massoni Amauri Antonio Menegário Laudi Cunha Leite Dante Pazzanese Duarte Lanna Virgílio Franco do Nascimento Filho 《X射线光谱测定》2011,40(6):424-426
This article describes a comparison of conventional energy‐dispersive X‐ray fluorescence (EDXRF) and synchrotron radiation total‐reflection X‐ray fluorescence (SRTXRF) for Co determination in ruminal fluid from Holstein cow. This element is used as marker for animal nutrition studies. For EDXRF, 200 µl of the sample were dried on 6.35 µm Mylar film at 60 °C. The excitation was carried out using an X‐ray tube with Mo target and Zr filter operated at 30 kV/20 mA. For SRTXRF, 10 µl of the sample were pipetted on a Lucite carrier and dried at 60 °C. In both the techniques, Ga was used as internal standard and the acquisition time was 200 s. The trueness of both techniques was evaluated through the standard addition method, the recoveries obtained by SRTXRF and EDXRF were 76 and 99%, and the limits of detection, 13 and 240 µg l?1, respectively. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
2.
Pedro R. Aranda Leandro Colombo Ernesto Perino Irma E. De Vito Julio Raba 《X射线光谱测定》2013,42(2):100-104
A novel and simple method was developed for the preconcentration and determination of mercury(II) from hydrochloric acid solutions through their adsorption on Aliquat 336 (tri‐octylmethylammonium chloride)‐activated carbon. The determinations were made directly on the solid by X‐ray fluorescence spectrometry, which had the advantage of eliminating the step of elution of the mercury retained. This preconcentration system enabled the determination of Hg(II) in drinking water samples at µg l?1 levels. A 1700‐fold enrichment factor was obtained. The described methodology showed excellent reproducibility, accuracy, and detection limits improvement by eliminating the step of elution of the analyte, replacing those methods based on cold vapor generation, reducing reagent consumption, and handling of samples. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
3.
Fábio de Souza Dias Lucylia S. Alves Walter Nei Lopes dos Santos Roy E. Bruns Marcos Almeida Bezerra 《光谱学快报》2013,46(6):388-392
ABSTRACT This paper applies statistical simplex-centroid design to mixture modeling for optimization of the liquid phase composition of cassava slurry leaves in the development of an analytical procedure for iron determination using flame atomic absorption spectrometry (FAAS). This procedure is based on a slurry formation from powdered cassava leaves and a liquid mixture composed of HNO3, HCl, and H2O2 after an ultrasonication process. A quadratic model fitted to the analytical response shows the existence of an experimental region, characterized by low proportions of H2O2, for which higher responses are obtained. The proposed procedure allows the determination of iron in the cassava leaves with a detection limit of 1.1 µg g?1. The precision expressed as relative standard deviation (%RSD, n = 10) was 1.5% for iron concentrations of 25 µg g?1. The developed procedure was validated by the comparison of results obtained from the application of the digestion procedure and the analysis of certified reference materials: Apple leaves (NIST 1515). Results found were in agreement with the certified values. The proposed method was applied for the determination of iron in four samples of cassava leaves acquired in markets of Feira de Santana City, Brazil. The concentration of iron found in the cassava leaves varied from 250.8 ± 0.7 to 283.4 ± 0.7 µg g?1. 相似文献
4.
Abstract Selenium determination in samples with a high copper content by hydride generation–inductively coupled plasma optical emission spectrometry (HG‐ICP‐OES) after online copper removal and selenium (VI) reduction is described. An activated carbon minicolumn was used for the retention of copper and its subsequent separation of Se. Se(VI) was then online reduced by heating into a PTFE coiled reactor with 12 M HCl. The analyte was introduced into a water stream containing sodium tetrahydroborate (NaBH4) in order to generate selenium hydride (H2Se). The detection limit (DL) obtained was 0.8 µg L?1, and the precision, expressed by the relative standard deviation (RSD), was 2.5% (n=10; 10 µg L?1 selenium level). The current method was applied to the Se determination in two copper reference materials, MBH‐39DK 3601 (with a Se content of 90 mg kg?1) and MBH‐39 DK 3604 (with a Se content of 15 mg kg?1). 相似文献
5.
G. D. Matos 《光谱学快报》2013,46(6):755-768
Abstract Thermospray flame furnace atomic absorption spectrometry (TS‐FF‐AAS) was employed for Cd(II) determination after online preconcentration. In this system, Cd(II) ions were adsorbed onto a minicolumn packed with grape bagasse. The elution of the metal ions was made with 1 mol L?1 HCl. Various parameters, such as pH, eluent type, concentration, volume, flow rate for preconcentration, and effect of interfering ions on the retention of the metal ions have been studied. The optimum pH for the adsorption was 3.0. The enrichment factor was 33.7. The limits of detection and quantification for Cd(II) were 0.03 and 0.11 µg L?1, respectively. The repetitivity and precision were 5.0 (5 minicolumns) and 4.6% (n=18). The stability of the minicolumns was evaluated from successive preconcentration/elution cycles (80 cycles, RSD 3.9%). The proposed method was applied for cadmium determination from certified reference materials, and good agreement was obtained at the 95% confidence level. 相似文献
6.
《X射线光谱测定》2005,34(3):207-212
An EDXRF technique with polarized (P) excitation has been introduced into geochemical analysis research in China. Preliminary work on a Spectro X‐Lab 2000 spectrometer showed that, in a total analysis time of 600 s per sample, over 30 elements can be quantified with detection limits of 0.5–30 µg g?1, comparable to internationally published values. To test the capability of the method for practical sample analysis, about 100 unknown samples were measured. Also, a comparison of P‐EDXRF and WDXRF with respect to results and performance was made. Both methods gave satisfactory results for over 30 elements. As P‐EDXRF has the advantages of higher throughput, lower purchase price, lower running costs and full spectra collection, it is more competitive for geochemical mapping analysis whereas WDXRF is advantageous for more precise analysis. However, the relatively smaller detection area with a polarized target may present some problems when analyzing light elements in pressed pellet samples or when the samples are not homogeneous enough. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
7.
D. Guimarães M. L. Carvalho M. Becker A. von Bohlen V. Geraldes I. Rocha J. P. Santos 《X射线光谱测定》2012,41(2):80-86
Measurements made in feces and urine of Wistar rats exposed to lead acetate (n = 20) in drinking water since the fetal period were compared with those obtained from a control group (n = 20) in order to assess the age influence on Pb excretion. The measurements were made in different collections of rats aging between 1 and 11 months. To determine the Pb content of the samples, total reflection X‐ray fluorescence (TXRF) and electrothermal atomic absorption spectrometry (ETAAS) were used for the urine samples and energy dispersive X‐ray fluorescence (EDXRF) was used for the feces. The results show high concentrations of Pb being eliminated from the organism by urine and feces in contaminated rats. Values vary from (600 ± 140) µg l?1 to (5 460 ± 115) µg l?1 in urine and from (4 500 ± 300) µg g?1 to (11 400 ± 3 300) µg g?1 in dry feces. The control rats show, in general, low lead concentrations or below detection limits. The fecal/urinary ratio was studied. It was shown to be about three to four orders of magnitude and positively correlated with time. It was verified in feces and urine that excretion decreases with the animal age and that this decrease is made by different levels of excretion. The excretions of Pb in urine and in feces are positively correlated. A good agreement was found between the results obtained with TXRF and ETAAS for urine samples. This work also stresses the suitability of these techniques in the study of Pb intoxication. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
8.
Yinhai Zhu Xiaoxia Xiang Enhui Liu Yuhu Wu Hui Xie Zhilian Wu Yingying Tian 《Ionics》2013,19(3):409-414
A microporous carbon material with large surface area was prepared by carbonizing and activating of phenol–melamine–formaldehyde resin, using K2CO3 as activation reagent. The textural characteristics of the carbon materials were characterized by scanning electron microscope, X-ray diffraction, Raman spectra, Brunauer–Emmett–Teller, elemental analyses, respectively. Results showed that the surface area and pore diameter of the activated carbon were 1,610 m2 g?1 and less than 2 nm. Electrochemical lithium insertion properties were also investigated. At a current density of 100 mA g?1, the activated carbon showed an enormous first-discharge capacity of 2,610 mAh g?1 and the first charge capacity of 992 mAh g?1. From the second cycle, the coulombic efficiency went up rapidly to above 95 %. The results indicated it may be a promising candidate as an anode material for lithium secondary batteries. 相似文献
9.
Abstract An automated sequential‐injection online preconcentration system was developed for the determination of lead by inductively coupled plasma–atomic emission spectrometry (ICP‐AES). The preconcentration of lead was performed with a minicolumn containing a lead‐selective resin, Analig Pb‐01, which was installed between a selection and a switching valve. In an acidic condition (pH 1), lead could be adsorbed on the resin. The concentrated lead was afterward eluted with 25 µL of 0.06 M nitrilotriacetic acid (NTA) solution (pH 9) and was subsequently transported into the nebulizer of ICP‐AES for quantification. The selectivity of the resin toward lead was examined using a solution containing a mixture of 61 elements. When a sample volume of 5 mL was used, the quantitative collection of lead (≥97%) was achieved, along with an enrichment factor of 19, a sampling frequency of 12 samples hr?1, a detection limit of 70 pg mL?1, and a lowest quantification limit of 100 pg mL?1. The linear dynamic range was 0.1 to 5 ng mL?1, and the relative standard deviation (n=9) was 0.5% at a 5 ng mL?1 Pb level. The detection limit of 30 pg mL?1 and lowest quantification limit of 50 pg mL?1 could be achieved when 10 mL of sample volume was used. The accuracy of the proposed method was validated by determining lead in the standard reference material of river water (SLRS‐4), and its applicability to the determination of lead in environmental river water samples was demonstrated. 相似文献
10.
Shayessteh Dadfarnia Ali Mohammad Haji Shabani Golnaz Shiralian Esfahani Elahe Kazemi 《光谱学快报》2013,46(2):140-145
ABSTRACTA simple and fast dispersive liquid–liquid microextraction based on solidification of floating organic drop has been developed for the separation and preconcentration of malachite green in water samples prior to its determination by flow injection spectrophotometry. Sodium lauryl sulfate, an anionic surfactant, was used for the ion-pair formation with malachite green. The factors affecting the ion-pair formation and extraction were optimized. Under the optimized conditions (volume of 1-undecanol as the extraction solvent, 40 μL; the volume of ethanol as the disperser solvent, 100 μL; sodium lauryl sulfate concentration, 7.5 × 10?7 mol L?1, and the pH of the sample, ~3.0), the calibration graph was linear over the range of 0.8–25 µg L?1 with the detection limit of 0.3 µg L?1 and the preconcentration factor of 750. The relative standard deviation at 7 µg L?1 (n = 6) was found to be 2.1%. The developed method was successfully applied to the determination of malachite green in river water and fish farming water samples. 相似文献
11.
ABSTRACT Rhizoma cyperi (tuberal part of Cyperus rotundus Linn) obtained from 15 different zones of China was studied to determine the contents of 16 trace elements such as 4 minor (Ca, K, Mg, and Na), 9 trace (Co, Cr, Cu, Fe, Mn, Mo, Ni, V, and Zn), and 3 toxic (Ag, Cd, and Pb) elements. The concentration determination of 16 elements was performed by atomic absorption spectrophotometry (AAS) after microwave-assisted digestion. A microwave-assisted digestion procedure based on the mixture nitric acid–hydrogen peroxide was evaluated. The method was successfully validated with the good recoveries (97–105%) against CRM GBW07603 (bush twigs and leaves). The calibration curve furnished good linear correlation coefficients (r = 0.9956–0.9999), excellent recoveries (99.35–103.7%), and limits of detection (LOD = 1–50 ng·mL?1) suitable to determine in Rhizoma cyperi. The results showed that K, Ca, Mg, and Na were the most abundant of the major elements in Rhizoma cyperi with average concentrations of K, 26,221 µg·g?1; Ca, 1097 µg·g?1; Mg, 714 µg·g?1, and Na, 293 µg·g?1, respectively. K element was determined for the first time in this plant. 相似文献
12.
Yang Gao Junfeng Li Yuqing Liu Liangzhao Zhong Chaozhu Shu Bo Yue Wentao Zhang 《Ionics》2017,23(9):2301-2310
Porous carbon nanosheets (PCNSs), porous carbon nanofibers (PCNFs), and flowerlike porous carbon microspheres (FPCMs) were successfully synthesized through a carbonization method combined with a simple acid pickling treatment using calcium citrate as the precursor. The as-prepared products show uniform morphologies, in which the FPCMs are self-assembled from PCNSs. As anodes of lithium-ion (Li-ion) batteries, these carbon materials deliver a stable reversible capacity above 515 mAh g?1 after 50 cycles at 100 mA g?1. Compared with PCNSs and PCNFs, FPCMs demonstrate preferable rate capability (378 mAh g?1 at 1 A g?1) and cyclability (643 mAh g?1 at 100 mA g?1). These results suggest that an appropriate select of morphology and structure will significantly improve the lithium storage capacity. The study also indicates that the novel shape-controlled porous carbon materials have potential applications as electrode materials in electronic devices. 相似文献
13.
Using a miniature X‐ray tube and silicon PiN diode detector, an approach to measuring lead (Pb) in bone phantoms was tested. The X‐ray tube was used to excite L‐line X‐ray fluorescence (L‐XRF) of lead in bone phantoms. The bone phantoms were made from plaster of Paris and dosed with varying quantities of lead. Phantoms were made in two sets with different shapes to model different bone surfaces. One set of bone phantoms was circular in cross‐section (2.5‐cm diameter), the other square in cross‐section (2.2 cm × 2.2 cm). Using an irradiation time of 180 s (real time), five trials were run for each bone phantom. Analysis was performed for both Lα and Lβ lead X‐rays. Based on these calibration trials, (3σ0/slope) minimum detection limits of 7.4 ± 0.3 µg Pb g?1 (circular cross‐section) and 8.6 ± 0.6 µg Pb g?1 (square cross‐section) were determined for the bare bone phantoms. To simulate a more realistic in vivo scenario with soft tissue overlying bone, further trials were performed with a resin material placed between the experimental system and the bone phantom. For the square cross‐section bone phantoms, a layer of resin with a thickness of 1.2 mm was used, and a minimum detection limit of 17 ± 3 µg Pb g?1 determined. For the circular cross‐section phantoms, a layer of resin with an average thickness of 2.7 mm was used. From these, a more realistic minimum detection limit for in vivo applications (43 ± 7 µg Pb g?1) was determined. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
14.
Preconcentration of mercury on polyaniline expands the horizon for energy dispersive X‐ray fluorescence determination
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P. S. Remya Devi S. Suvarna M. Ghosh G. Kiran Kumar R. Verma A. V. R. Reddy 《X射线光谱测定》2016,45(3):162-168
Hg(II) was sorbed on polyaniline from aqueous solutions, followed by determination using energy dispersive X‐ray fluorescence spectrometry. Distribution coefficient of Hg(II) on polyaniline was about 4 × 103 in water, whereas distribution coefficient was 1.2 × 104 at 0.1 M HCl and decreased drastically with increase in HCl concentration. Rapid kinetics of sorption was evinced by the 80% uptake within the initial 1 min and quantitative sorption within 5 min of equilibration. The sorption was found to follow Langmuir isotherm model, and the Langmuir capacity was calculated as 19.7 mg g?1. The ability of polyaniline to form stable and homogeneous pellets facilitated the energy dispersive X‐ray fluorescence determination without recourse to elution. Detection limit of Hg was found to be 22 ng, considering 100 mg pellet of polyaniline. The apparent detection limit was 6 pg, as the preconcentration factor of Hg(II) on polyaniline was 4 × 103. The developed method is at par with the established method for mercury determination, namely, cold vapor atomic absorption spectrometry. Accuracy of the method was established by the analysis of the International Atomic Energy Agency reference materials, namely, hair and lichen, for Hg(II). Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
15.
LiFePO4/C composite cathode material has been synthesized by a carbothermal reduction method using β-FeOOH nanorods as raw materials and glucose as both reducing agent and carbon source. The results indicate that the content of carbon and the morphology of raw material have effect on the electrochemical performance of the final LiFePO4/C material. Sample LFP14 with a carbon content of 2.79 wt.% can deliver discharge capacities of 158.8, 144.3, 111.0, and 92.9 mAh g?1 at 0.1, 1, 10, and 15 C, respectively. When decreasing the current from 15 C back to 0.1 C, a discharge capacity of 157.5 mAh g?1 is recovered, which is 99.2 % of its initial capacity. Therefore, as a kind of cathode material for lithium ion batteries, this LiFePO4/C material synthesized via a carbothermal reduction method is promising in large-scale production, and has potential application in upcoming hybrid electric vehicles or electric vehicles. 相似文献
16.
《光谱学快报》2013,46(5-6):515-529
A simple method has been developed for the determination of Chlorsulfuron in pesticide formulations by Fourier Transform Infrared (FTIR). Samples were diluted with CHCl3? , and the FTIR spectra of the samples and standards were obtained at a nominal resolution of 4 cm? 1 from 4000 to 900 cm? 1 with the accumulation of 25 scans. Chlorsulfuron determination was based on the measurement of peak area values from 1373 to 1363 cm? 1 which were corrected by use of a two points baseline defined from 1401 to 1302 cm? 1. The limit of detection achieved, which was of the order of 6 µg g? 1, was appropriate for the determination of Chlorsulfuron in commercially available formulations. FTIR results were statistically comparable with those found by High Performance Liquid Chromatography (HPLC). The procedure reduces organic solvent consumption per sample to less than 3 ml CHCl3, reduces waste generation and increases the sample measurement frequency up to 60 h? 1. 相似文献
17.
For Li-S batteries, commercial application was hindered by the insulating nature of S and the solubility of polysulfide. Porous carbon materials had proven themselves to be an ideal immobilizer host for S impregnation. Herein, carbon aerogels (CAs) with tunable pore microstructure were synthesized from resorcinol-formaldehyde reaction with increasing catalyst concentration and pyrolysis under high temperature. The results demonstrated that the catalyst concentration played a key role in tuning the porous microstructure of the CAs. In addition, potassium hydroxide (KOH) was introduced to activate the obtained CAs. The activated carbon aerogels (A-CAs) with hierarchical porous structure exhibited the highest specific surface area (1837.4 m2 g?1) and the largest total pore volume (2.276 cm3 g?1), which combined the advantages of both mesoporous and microporous. The effects of porous microstructure, specific surface area, and pore volume of the CAs and A-CAs on S incorporation were studied. The S/A-CAs exhibited significantly improved reversible capacity (1260 mAh g?1 at a rate of 0.1 C), enhanced high-rate property, and excellent cycling performance (229 mAh g?1 after 500 cycles at 1 C) as a cathode for Li-S batteries. 相似文献
18.
《X射线光谱测定》2003,32(1):57-59
A simple and fast method was developed for the determination of traces of Fe, Mn, Cu, Cr, Ni, Zn and Mo in endive using wavelength‐dispersive x‐ray fluorescence spectrometry. Plants were grown in different sewage sludge compositions for 60 days in greenhouse conditions. Samples were compacted and analyzed after drying, milling and homogenization. The method was validated using certified standard reference materials. The results were compared with those obtained by atomic absorption spectrometry. Good agreement for all elements was obtained. The detection limits were found to be Fe 1, Mn 3, Cu 2, Cr 5, Ni 1, Zn and Mo 3 µg g?1. These results permitted the evaluation of the potential use of sewage sludge as an agricultural amendment. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
19.
Zhewei Yang Yang Yang Huajun Guo Zhixing Wang Xinhai Li Yu Zhou Jiexi Wang 《Ionics》2018,24(11):3405-3411
Compact-structured silicon/carbon composites consisting of silicon, graphite, and coal tar pitch pyrolysis carbon are prepared via two heating procedures after liquid solidification. The first heating procedure plays a key role in the formation of compact-structured silicon/carbon composites, in which the coal tar pitch has a good fluidity at 180 °C above the softening temperature, and it is easy to form a uniform coating on the surface of materials. At the same time, the fluidic coal tar pitch could also fill the voids between particles to form compact-structured silicon/carbon composites. As-prepared silicon/carbon composites exhibit moderate reversible capacity of 602.4 mAh g?1, high initial charge-discharge efficiency of 82.3%, and good cycling stability with the capacity retention of 93.4% at 0.1 A g?1 after 50 cycles. It is noteworthy that the synthetic method is scalable which is suitable for mass production. 相似文献
20.
A high specific surface area (2798.8 m2 g?1) of nanoporous carbon microsphere (NPCM) is prepared by activated carbon microsphere in hot CO2 atmosphere, which is used as matrix material of sulfur to prepare NPCM/sulfur composite cathode material by a melt-diffusion method. The NPCM/sulfur composite cathode material with the sulfur content of 53.5% shows high discharge capacity; the initial discharge capacity is 1274 mAh g?1 which maintains as high as 776.4 mAh g?1 after 50 cycles at 0.1 C current. At high current density of 1 C, the NPCM/sulfur cathode material still shows initial discharge capacity of 830.3 mAh g?1, and the reversible capacity retention is 78% after 50 cycles. To study the influence of different sulfur content of NPCM/sulfur cathode material to the performance of Li–S battery, the different sulfur content of NPCM/sulfur composite cathode materials is prepared by changing the thermal diffusion time and the ratio of sulfur powder to NPCM. The performance of NPCM/sulfur cathode material with different sulfur content is studied at a current of 0.1 C, which will be very important to the preparation of high-performance sulfur/carbon cathode material with appropriate sulfur content. 相似文献