Determination of aluminium in silicon by electrothermal atomic absorption spectrometry

The sample is decomposed with hydrofluoric and nitric acids and the diluted solution is injected into the graphite furnace. For a 100-mg sample, the detection limit (3 σ) is 1.2 μg AI g^-1. The coefficient of variation is 3–13% for 9–7000 μg Al g^-1 in silicon.     

Determination of silicon in aluminium by 14 MeV neutron activation analysis

A method has been developed for determining silicon in aluminium by fast neutron activation. It is based on the separation of two gamma lines by a Ge(Li) detector: the 1.73 MeV line from the product of²⁷Al(n, α)²⁴Na and the 1.78 MeV line from the²⁸Si(n, p)²⁸Al reaction. In the case of aluminium-silicon alloys 100 μg silicon can be determined, with an error of 10% in an aluminium sample of 1 g. This work was supported in part by the International Atomic Energy Agency.     

Determination of vanadium in animal tissues by PIXE and AAS

Proton induced X-ray emission (PIXE) and atomic absorption spectroscopy (AAS) were used for vanadium determination in animal tissues. The vanadium concentration levels were determined in blood, kidneys and livers taken from rats. Two groups of the animals were treated with different diets. The diet for the first group was supplemented with vanadium compounds while the diet for the second one was assumed to be a normal diet. The second group was treated as control. In order to achieve the best minimum detectable limit (MDL)¹ the samples were subject to a special sample preparation procedure. Blood and kidneys were mineralized with an APDC compound. The mineralization process was performed according to the procedure described previously.² The application of PIXE³ is very useful for different types of samples. PIXE measurements were performed with a proton beam at the Institute of Nuclear Physics in Cracow, Poland while the AAS measurements were done at the Institute of Molecular Biology, Jagiellonian University, Poland. The concentration levels of vanadium in blood and kidneys are compared and discussed. There were no significant statistical differences between results of vanadium concentration levels determined by the abovementioned techniques. The PIXE technique had the advantage over the AAS technique of giving a broad spectrum of trace elements analyzed in a single measurement. Therefore with the help of sample preparation procedure the application of the PIXE method seems to be suitable for such analyzes.     

Isomorphous substitution of framework silicon by aluminium in silicalite: factors determining resolution of 29Si magic-angle-spinning NMR spectra of pentasil zeolites

The hypothesis that the resolution of ²⁹Si magic-angle-spinning NMR spectra of zeolite ZSM-5/silicalite is governed by tetrahedral Al content is questioned by showing that the introduction of substantial amounts of framework Al into silicalite does not impair spectral resolution. Possible alternative mechanisms are discussed.     

Toluene disproportionation over decationized and aluminium deficient zeolites

The activities of aluminium deficient HL, HY, HX, H-mordenite zeolites are predominantly higher in comparison with those of normal H-zeolites. The increase in acid strength with dealumination of these zeolites enhances the catalytic activity.

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- HL, HY, HX, , -. .

     

Determination of trace elements in zeolites by laser ablation ICP-MS

Laser ablation inductively coupled plasma mass spectrometry using a quadrupole-based mass spectrometer (LA-ICP-QMS) was applied for the analysis of powdered zeolites (microporous aluminosilicates) used for clean-up procedures. For the quantitative determination of trace element concentrations three geological reference materials, granite NIM-G, lujavrite NIM-L and syenite NIM-S, from the National Institute for Metallurgy (South Africa) with a matrix composition corresponding to the zeolites were employed. Both the zeolites and reference materials were fused with a lithium borate mixture to increase the homogeneity and to eliminate mineralogical effects. In order to compare two different approaches for the quantification of analytical results in LA-ICP-MS relative sensitivity coefficients (RSCs) of chemical elements and calibration curves were measured using the geostandards. The experimentally obtained RSCs are in the range of 0.2-6 for all elements of interest. Calibration curves for trace elements were measured without and with Li or Ti as internal standard element. With a few exceptions the regression coefficients of the calibration curves are better than 0.993 with internal standardization. NIM-G granite reference material was employed to evaluate the accuracy of the technique. Therefore, the measured concentrations were corrected with RSCs which were determined using lujavrite reference material NIM-L. This quantification method provided analytical results with deviations of 1-11% from the recommended and proposed values in granite reference material NIM-G, except for Co, Cs, La and Tb. The relative standard deviation (RSD) of the determination of the trace element concentration (n = 5) is about 1% to 6% using Ti as internal standard element. Detection limits of LA-ICP-QMS in the lower microg/g range (from 0.03 microg/g for Lu, Ta and Th to 7.3 microg/g for Cu, with the exception of La) have been achieved for all elements of interest. Under the laser ablation conditions employed (lambda: 266 nm, repetition frequency: 10 Hz, pulse energy: 10 mJ, laser power density: 6 x 10(9) W/cm2) fractionation effects of the determined elements relative to the internal standard element Ti were not observed.     

Determination of major and trace elements in bones by simultaneous PIXE/PIGE analysis

The training process and training programs in both commercial nuclear plants and Department of Energy (DOE) nuclear facilities have improved significantly in the years following the Three-Mile Island (TMI) accident. This article describes some of these changes, including the reasons behind the change, the affected population, the training accreditation process and performance-based training, and the benefits of the changes.     

Determination of water in zeolites by a neutron reflection method

Water content in zeolites has been determined by an improved neutron reflection method using a Pu-Be neutron source of 10⁶ n·s^–1 intensity and a BF₃ counter. It was found that the water content of different types of zeolites collected in Hungary varies between 9 and 12 wt.%. The standard deviation of the determination does not exceed 0.5 wt.%. The matrix effect on the sensitivity and accuracy was also studied. An approximate relation is given between the count rate and the neutron physical parameters of the samples.     

Determination of trace elements in zeolites by laser ablation ICP-MS

Laser ablation inductively coupled plasma mass spectrometry using a quadrupole-based mass spectrometer (LA-ICP-QMS) was applied for the analysis of powdered zeolites (microporous aluminosilicates) used for clean-up procedures. For the quantitative determination of trace element concentrations three geological reference materials, granite NIM-G, lujavrite NIM-L and syenite NIM-S, from the National Institute for Metallurgy (South Africa) with a matrix composition corresponding to the zeolites were employed. Both the zeolites and reference materials were fused with a lithium borate mixture to increase the homogeneity and to eliminate mineralogical effects. In order to compare two different approaches for the quantification of analytical results in LA-ICP-MS relative sensitivity coefficients (RSCs) of chemical elements and calibration curves were measured using the geostandards. The experimentally obtained RSCs are in the range of 0.2-6 for all elements of interest. Calibration curves for trace elements were measured without and with Li or Ti as internal standard element. With a few exceptions the regression coefficients of the calibration curves are better than 0.993 with internal standardization. NIM-G granite reference material was employed to evaluate the accuracy of the technique. Therefore, the measured concentrations were corrected with RSCs which were determined using lujavrite reference material NIM-L. This quantification method provided analytical results with deviations of 1–11% from the recommended and proposed values in granite reference material NIM-G, except for Co, Cs, La and Tb. The relative standard deviation (RSD) of the determination of the trace element concentration (n = 5) is about 1% to 6% using Ti as internal standard element. Detection limits of LA-ICP-QMS in the lower μg/g range (from 0.03 μg/g for Lu, Ta and Th to 7.3 μg/g for Cu, with the exception of La) have been achieved for all elements of interest. Under the laser ablation conditions employed (λ: 266 nm, repetition frequency: 10 Hz, pulse energy: 10 mJ, laser power density: 6 × 10⁹ W/cm²) fractionation effects of the determined elements relative to the internal standard element Ti were not observed. Received: 7 April 2000 / Revised: 25 May 2000 / Accepted: 31 May 2000     

碱消解-电感耦合等离子体光谱测定铝灰中铝

建立了电感耦合等离子体光谱法测定铝灰中铝含量的方法。针对铝灰样品中铝含量高,难消解的特点,研究了酸溶法和碱熔法对铝灰样品的消解方法,并对熔融时间进行了试验,确定采用碳酸钠,碳酸钾,硼酸在900℃高温下熔融20min消解铝灰样品。同时采用传统滴定法和电感耦合等离子体光谱法对实验结果进行了比对,确定测定结果的准确性。方法检出限为0.017 mg/L,测定下限为0.028 mg/L,3个样品的相对标准偏差在1.46%~3.85%之间,加标回收率在96.63%~98.40%之间。该方法样品消解完全,流程短,操作简单,快速,测定准确度高,可以满足铝灰样品中铝含量的测定。     

XRF induced by PIXE: Comparison with PIXE

Two different modes of sample excitation have been used for elemental analysis of thin standard reference materials and of chemical standards with known composition. PIXE /2.5 MeV protons/ and XRF induced by PIXE, will be called XRF-PIXE /2.5 MeV protons on Mo primary target/. The same samples were alternatively exposed to protons and X-ray beams. The sensitivities under standard running conditions are determined for both an XRF-PIXE and a PIXE analysis system. It is shown that the sensitivity of the PIXE spectrometer depends strongly on the sample matrix, whereas the XRF-PIXE sensitivity is rather constant with respect to different kinds of samples. In addition, the advantages of one mode of excitation on the other are discussed. It is shown that XRF-PIXE can be a useful complement to PIXE analysis.     

Prepolymer film growth by adsorption out of solution on silicon and aluminium

A cyanurate prepolymer has been applied to smooth silicon wafers or to distinctly structured aluminium coatings. The surface composition of the substrates has been investigated by X-ray Photoelectron Spectroscopy (XPS), Auger Electron Spectroscopy (AES) and ellipsometry. The application methods, spin coating and dip coating represent adsorption by a technical process exerting significant shear stresses or nearly equilibrated conditions, respectively. The mean tickness of the prepolymer film has been adjusted by variation of the concentration of the solution and checked by ellipsometry. Atomic Force Microscopy (AFM) monitored the development of the respective film morphologies of all 4 systems (silicon/aluminium, spin/dip coating) in the mean film thickness range from 1 to 50 nm.     

Determination of aluminium in aerosols by flameless atomic-absorption spectrometry

A method is reported for the determination of aluminium in aerosols collected on Whatman 41 cellulose filters. In the destruction procedure, provision was made to eliminate silica by hydrofluoric acid treatment. Analysis of the solutions was performed by the flameless atomic-absorption technique. The accuracy was checked by using data from instrumental neutron-activation analysis (INAA) and standard reference materials. An analogue integrator gave a better linearity and detection limit than conventional peak-reading.     

Prepolymer film growth by adsorption out of solution on silicon and aluminium

A cyanurate prepolymer has been applied to smooth silicon wafers or to distinctly structured aluminium coatings. The surface composition of the substrates has been investigated by X-ray Photoelectron Spectroscopy (XPS), Auger Electron Spectroscopy (AES) and ellipsometry. The application methods, spin coating and dip coating represent adsorption by a technical process exerting significant shear stresses or nearly equilibrated conditions, respectively. The mean tickness of the prepolymer film has been adjusted by variation of the concentration of the solution and checked by ellipsometry. Atomic Force Microscopy (AFM) monitored the development of the respective film morphologies of all 4 systems (silicon/aluminium, spin/dip coating) in the mean film thickness range from 1 to 50 nm.     

X射线荧光光谱法测定不同类型分子筛中氧化物的含量

扫描电子显微镜是一种常用的表征工具,可直观观察样品表面微观形貌. 由于分子筛样品中的硅铝成分而造成的二次电子产率低、耐电子束程度差、导电性不佳等特性,采用扫描电子显微镜进行形貌表征时会出现信号弱、荷电效应、表面细微结构损失等问题. 扫描电子显微镜表征时,加速电压、束斑尺寸、工作距离等是普遍的调节参数. 通过优化上述参数,对ZSM-5分子筛的扫描电子显微镜成像质量进行研究. 结果表明,低加速电压、束斑尺寸为3.0、工作距离小于5 mm时,对样品测试即可获得高质量扫描电子显微镜图像. 对比发现,镀膜后成像质量反而变差.     

Determination of aluminium and sodium in tungsten by non-destructive activation analysis

The sodium and aluminium content of tungsten has been measured by thermal neutron activation analysis. The concentration of aluminium was evaluated from the 1.78 MeV, and that of sodium from the 2.76 MeV full energy peaks. The minimum detectable concentrations of impurities were 0.04 microg of aluminium and 0.07 microg of sodium per 100 mg of tungsten.     

铝(Ⅲ)-氧氟沙星-十二烷基硫酸钠荧光体系测定微量铝的研究

在NaAc HAc介质中,溶液中的铝(Ⅲ)能与氧氟沙星和十二烷基硫酸钠(SDS)反应生成一稳定的络合物,使氧氟沙星的内源性荧光显著增强,据此建立了铝(Ⅲ) 氧氟沙星 SDS体系测定铝(Ⅲ)的荧光分析新方法。该体系的最大激发波长λex=365nm,最大发射波长λem=480nm,铝(Ⅲ)浓度在2.0×10-7～5.0×10-5mol L范围内,与荧光增强程度成正比。该方法可直接用于水样和食品中微量铝(Ⅲ)的测定。     

Determination of aluminium and chromium in serum by atomic absorption spectrometry

Summary The optimal conditions for the determination of aluminium and chromium in blood serum are proposed. Several sample pretreatment procedures for the purpose are compared. The best results are obtained by sample dilution with nitric acid (0.1 mol/l) and addition of Mg(NO₃)₂ as modifier with a magnesium concentration of 0.2 mg/ml. This procedure has been used for studying the intestinal intake of aluminium by patients after oral administration of aluminium compounds.