金属材料分析国内外标准中波长色散X射线荧光光谱法的应用

对国内外金属材料分析方法标准(包括ASTM、JIS、EN和GB)中应用波长色散X射线荧光光谱法(XRF)的现状,从方法所涵盖的测定元素及其测定的含量范围以及谱线重叠和基体效应的校正等几个方面,并以钢铁分析中的应用为例作了评述。美国材料与试验协会在2012-2016年间先后发布了3个XRF标准方法,分别应用于铸铁、不锈钢、合金钢和低合金钢的分析,测定元素达13项,根据相关钢材的技术规格确定了各元素含量的测定范围。日本工业标准调查会于1997年并于2010年和2013年经修订公布了钢铁XRF分析法JIS标准,可测定各类钢材中主量、次量以及痕量元素达31项,其中镍、铁、钴和测定下限分别延伸至99.5%,50%和60%,从而使此方法有可能扩展应用于镍基、铁镍基和钴基高温合金的分析。我国先后于2007年和2018年由国家标准经主管部门颁布了XRF分析钢铁和高合金钢的两个标准,可测定这2类钢材中的元素为13项和11项,其测定含量范围系根据材料的技术规格确定。关于谱线重叠和基体效应的校正,各标准中在相关部分作了说明,而ASTM有两则独立标准专门论述这两个问题。在此评述对其他金属材料的XRF分析标准也作了介绍(引用文献15篇)。     

Trace analysis of high-purity graphite by LA-ICP-MS

Laser-ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) has been established as a very efficient and sensitive technique for the direct analysis of solids. In this work the capability of LA-ICP-MS was investigated for determination of trace elements in high-purity graphite. Synthetic laboratory standards with a graphite matrix were prepared for the purpose of quantifying the analytical results. Doped trace elements, concentration 0.5 microg g(-1), in a laboratory standard were determined with an accuracy of 1% to +/- 7% and a relative standard deviation (RSD) of 2-13%. Solution-based calibration was also used for quantitative analysis of high-purity graphite. It was found that such calibration led to analytical results for trace-element determination in graphite with accuracy similar to that obtained by use of synthetic laboratory standards for quantification of analytical results. Results from quantitative determination of trace impurities in a real reactor-graphite sample, using both quantification approaches, were in good agreement. Detection limits for all elements of interest were determined in the low ng g(-1) concentration range. Improvement of detection limits by a factor of 10 was achieved for analyses of high-purity graphite with LA-ICP-MS under wet plasma conditions, because the lower background signal and increased element sensitivity.     

Recent developments in assessment of bio-accessible trace metal fractions in airborne particulate matter: A review

In the last years a great deal of research has been focused on the determination of harmful trace metals such as Cd, Co, Cr, Cu, Ni or Pb in airborne particulate matter (APM). However, the commonly applied determination of total element concentrations in APM provides only an upper-end estimate of potential metal toxicity. For improved risk assessment it is important to determine bio-accessible concentrations instead of total metal contents. The present review gives an overview of analytical procedures reported for measurement of bio-accessible trace metal fractions in APM. The different approaches developed for extraction of soluble trace metals in APM are summarized. Furthermore the analytical techniques applied for accurate determination of dissolved trace metals in the presence of complex sample matrix are presented. Finally a compilation of published results for bio-accessible trace metals in APM is included.     

Calibration of laser-ablation ICP-MS. Can we use synthetic standards with pneumatic nebulization?

An approach for the determination of trace element concentrations in high purity metals, using an inductively coupled plasma mass spectrometer (ICP-MS) with a laser-ablation system for direct solid sample introduction after calibration with nebulized liquid standards was made. Due to the inherent differences in the rate of sample introduction with laser-ablation and pneumatic nebulization, a matrix element must be used as an internal standard. This is problematical for elements that have no isotope with a relative abundance of less than 0.1 %, since the ion signals would be too high for direct measurement, and reduction of the ablation rate would compromise the sensitivity for trace elements. Due to the high stability of ICP-unit and mass filter of the instrument used, it was found that the tail of a mass-peak of the matrix element could be used as an internal standard. Therefore, a position at –0.5 amu from the matrix-isotope (e.g. ^62.5Cu in copper samples) was used for internal standardization. The standard deviation of this signal in a period of 2.5 h was 3.6% RSD with no notable drift when the laser ablation was used for sample introduction. The calibration of the matrix-element by nebulizing liquid standards showed that the ion signal measured on the peak-tail is directly proportional to the element concentration in the ICP. This indicates that the peak shape is not only stable, but also independent of the peak height. The advantages of this method lie in the easy preparation of calibration standards for quantitative measurements with a laser-ablation system and access to homogeneous standards for materials, that are difficult to homogenize in the solid state. The calibration of the traces is performed relatively to a fixed concentration of the matrix element. Calibrations were carried out for trace concentrations in high purity copper and good recoveries were obtained for high-purity reference standards. Received: 23 February 1998 / Revised: 20 July 1998 / Accepted: 25 July 1998     

Suspensions of biological tissues in alkaline medium for the determination of copper, manganese and cobalt by electrothermal atomic absorption spectrometry

Electrothermal atomic absorption spectrometry was applied to the determination of copper, manganese and cobalt in biological tissues of which small amounts are available only. The samples (10 mg of mice tissue) were suspended in 1 mL of water containing tetramethylammonium hydroxide, Triton X-100 and silicone antifoam. The sample was homogenized by heating to 60 °C for 5 min, submitted to dilution if necessary, and injected into the atomizer. Wall atomization was used for Cu and Mn, and platform atomization for Co. Calibration was carried out using aqueous standards for copper and manganese determination. The determination of cobalt suffered from a matrix effect and, in this case, calibration was enabled by using a suspension of a cobalt-free muscle sample. The detection limits are 25, 20 and 62 ng?g^?1. The results obtained for five certified reference materials demonstrated the reliability of the procedures for the determination of the three analytes in normal and dystrophic mice tissue.     

Calibration of laser-ablation ICP-MS. Can we use synthetic standards with pneumatic nebulization?

An approach for the determination of trace element concentrations in high purity metals, using an inductively coupled plasma mass spectrometer (ICP-MS) with a laser-ablation system for direct solid sample introduction after calibration with nebulized liquid standards was made. Due to the inherent differences in the rate of sample introduction with laser-ablation and pneumatic nebulization, a matrix element must be used as an internal standard. This is problematical for elements that have no isotope with a relative abundance of less than 0.1 %, since the ion signals would be too high for direct measurement, and reduction of the ablation rate would compromise the sensitivity for trace elements. Due to the high stability of ICP-unit and mass filter of the instrument used, it was found that the tail of a mass-peak of the matrix element could be used as an internal standard. Therefore, a position at –0.5 amu from the matrix-isotope (e.g. ^62.5Cu in copper samples) was used for internal standardization. The standard deviation of this signal in a period of 2.5 h was 3.6% RSD with no notable drift when the laser ablation was used for sample introduction. The calibration of the matrix-element by nebulizing liquid standards showed that the ion signal measured on the peak-tail is directly proportional to the element concentration in the ICP. This indicates that the peak shape is not only stable, but also independent of the peak height. The advantages of this method lie in the easy preparation of calibration standards for quantitative measurements with a laser-ablation system and access to homogeneous standards for materials, that are difficult to homogenize in the solid state. The calibration of the traces is performed relatively to a fixed concentration of the matrix element. Calibrations were carried out for trace concentrations in high purity copper and good recoveries were obtained for high-purity reference standards. Received: 23 February 1998 / Revised: 20 July 1998 / Accepted: 25 July 1998     

Determination of trace elements in semiconductor materials by neutron activation analysis using the radioisotope addition technique

The determination of trace elements in highly activated matrix components was carried out by neutron activation analysis using the radioisotope addition technique. The method is based on the addition to the irradiated test sample of a radioisotope which is a diffeent nuclide of the element to be determined. After separation, the chemical yield is calculated from the radioactivity added and the element is determined by an ordinary technique. Twelve elements in indium phosphide and eight elements in gallium arsenide could be determined by the method.     

A proposed sampling constant for use in geochemical analysis

The error in a determination of an element in a rock or mineral sample depends on the analytical error, the weight of sample analysed, and the nature and history of the laboratory sample. The most probable result is not independent of the weight of sample analysed. This is due to the fact that trace constituents often reside in isolated mineral grains. The chance of such mineral grains appearing in any one analysed sample becomes more remote as the sample weight decreases, even when rock or mineral samples are reduced to fine powders. Such subsampling errors can be controlled through the use of sampling constants. These may be estimated by several procedures, including repetitive determination of a constituent and physical measurement of relevant sample characteristics. Sampling constants can be usefully employed during the establishment and certification of reference samples or standards. When subsampling is deficient, analytical results may yield erroneously low values, sometimes with high precision. High precision never implies high accuracy; it may be a symptom of gross error.     

电弧制样-电感耦合等离子体光谱分析法直接测定合金钢中的痕量元素

本文提出了电弧制样与电感耦合等离子体(ICP)相结合光谱直接测定合金钢中痕量元素的新方法。采用高压/低电流直流电弧放电作为试样蒸发的蒸发源,由于阴极弧斑在金属表面上方作快速均匀的移动,使试样剥离形成金属气溶胶,它在载气流(Ar)的作用下引入ICP。研究了试样的蒸发行为、放电气体介质、基体组成变化的影响及ICP工作参数等。用本法测定Co、Ni、Cr、Mn、Mo、Nb、Ta、Ti、V、W和Zr的检出限为0。x至xμg/g。分析了低、高合金钢试样,结果与NBS标准值吻合。     

Sequential flow analysis coupled with ACSV for on-line monitoring of cobalt in the marine environment

The development of a compact instrument for on-line measurement of trace metals in seawater is described. The system is based on adsorptive cathodic stripping voltammetry (ACSV), and on the concept of sequential flow analysis, to perform on-line measurements with controlled perturbation of natural equilibria of the element. The design combines a low volume flow cell with a miniature solenoid pump and valves to achieve low power consumption. The flow segmentation is time-controlled and the detection step takes place in a well-defined part of the flow stream where reagent and sample occur mixed. The system was tested on the determination of cobalt in seawater but it is likely that the same technique can be used to determine other metals detectable by CSV. The determination range was 6–1050 pmol/L cobalt with a detection limit (3σ) of 6 pmol/L. The measurement rate was about 60 h^–1. Comparative measurements were carried out using continuous flow analysis. The apparatus was used continuously on board a ship to determine the distribution pattern of cobalt in surface waters off the coast of California.     

Microwave-assisted versus conventional decomposition procedures applied to a ceramic potsherd standard reference material by inductively coupled plasma atomic emission spectrometry

Inductively coupled plasma atomic emission spectrometry (ICP-AES) is a powerful, sensitive analytical technique with numerous applications in chemical characterization including that of ancient pottery, mainly due to its multi-element character, and the relatively short time required for the analysis. A critical step in characterization studies of ancient pottery is the selection of a suitable decomposition procedure for the ceramic matrix. The current work presents the results of a comparative study of six decomposition procedures applied on a standard ceramic potsherd reference material, SARM 69. The investigated decomposition procedures included three microwave-assisted decomposition procedures, one wet decomposition (WD) procedure by conventional heating, one combined microwave-assisted and conventional heating WD procedure, and one fusion procedure. Chemical analysis was carried out by ICP-AES. Five major (Si, Al, Fe, Ca, Mg), three minor (Mn, Ba, Ti) and two trace (Cu, Co) elements were determined and compared with their certified values. Quantitation was performed at two different spectral lines for each element and multi-element matrix-matched calibration standards were used. The recovery values for the six decomposition procedures ranged between 75 and 110% with a few notable exceptions. Data were processed statistically in order to evaluate the investigated decomposition procedures in terms of recovery, accuracy and precision, and eventually select the most appropriate one for ancient pottery analysis.     

Application of RF GDMS for trace element analysis of nonconducting La0.65Sr0.3MnO3 ceramic layers

Radio-frequency glow discharge mass spectrometry (RF GDMS) has been applied to the determination of trace elements in ceramic perovskite layers (La_0.65Sr_0.3MnO₃) using synthetic standards. For the preparation of these standards high-purity powder of the basic material (La_0.65Sr_0.3MnO₃) was doped with trace elements in concentrations from 20 to 500 μg/g and the mixture was pressed to compact samples. The resulting calibration curves and the calculated relative sensitivity factors (RSF) differed only from 0.4 to 2 for different elements. For nearly all elements the standard deviations in the determination of trace elements in La_0.65Sr_0.3MnO₃ were better than 15% and detection limits (using the 3σ-criterion) were below 10 μg/g. Changes of the discharge parameters (RF power, pressure of the discharge gas (Ar) in the RF glow discharge) have no significant influence on the sensitivity to elements.     

Speciation of trace elements in biological materials: trends and problems.

In the determination of trace elements in biological materials, speciation is of particular importance as the essential effects or toxicity of an element and its metabolic behaviour depend to a large extent on the chemical forms in which it is present in the organism. Speciation is relatively easy if a property of a particular compound can be measured directly in the sample without interference from the other components of the material, e.g., the enzymic activities of the metallo-enzymes. Another possibility for speciation is immunoassay, which likewise allows direct determination of a particular trace element. At present, however, with most trace elements both fractionation methods and analytical procedures have to be combined and speciation has to be carried out by determining the elemental content in the separated fractions. The methods and apparatus used in taking, storing and preparing the samples can, therefore, not be selected solely according to the requirements of trace element determination, but it is also essential to ensure that the biological structures of the components to be separated remain intact. In this work the need for speciation in the investigation of the toxic and essential effects of trace elements is shown with the help of some examples, and the problems that can occur in the various steps of sampling, storage and sample preparation are discussed.     

辉光放电质谱法测定核级石墨粉中痕量杂质

建立了直流辉光放电质谱法(DC-GDMS)测定核级石墨粉中痕量杂质元素的方法。用一定的压力将石墨粉镶嵌在高纯铟片上,形成一个直径约为5 mm的圆形石墨薄层,用铟片辅助石墨粉放电,实现了粉状样品直接检测。优化的实验条件为放电电流0.8 mA,放电电压1.2 kV,放电气体流速0.437 mL/min。用石墨粉标准样品(19J T61029)单点校准了仪器相对灵敏度因子,消除基体效应,实现15个关键杂质元素定量分析。方法检出限为5.0 ng/g,在单侧0.05显著性水平下,利用Student's t检验,方法测定结果t值均小于临界值,与标准值无显著性差异。相对标准偏差(RSD)均小于10%。本方法与电感耦合等离子体光谱法测定结果比较,相对误差在2.4%~17.4%之间。     

Sample digestion procedures for trace element determination

A survey is given of both dry and wet procedures for matrix dissolution for the purpose of trace element determination in all kinds of materials. Various methods are compared and evaluated. With wet digestion methods special attention is paid to mixtures of strong acids and oxidants. Emphasis is laid on the completeness of these digestions, for which the use of HF is a prerequisite.     

Trace elements in soil: Their determination and speciation

Summary The different types of soil analysis are reviewed in-outline and some recent developments and methodologies are discussed.For the determination of the total trace element content of soils, conventional, multi-element, solid sample methods including d.c. arc optical emission and spark source mass spectrometric procedures are briefly considered together with the potential of current X-ray fluorescence, solid sample graphite furnace atomic absorption and glow discharge mass spectrometry.The use of strong acid digestion, with for example aqua regia, for the determination of pseudo-total concentrations of heavy or toxic metal accumulations in soil is described.The limitations of solution methods for multi-element analysis of soils are outlined together with the prospects for the use of soil slurries to eliminate the sample preparation and dilution problems associated with the dissolution of soils. The difficulties in taking reproducible and representative samples of inhomogeneous materials such as soils are highlighted.Trace element speciation can be defined as the identification and quantification of the different forms or phases in which they occur in soils. Some examples of such procedures and extractants for both essential and toxic elements in soils are presented. The difficulties of trace element speciation in soils as distinct from soil extracts or soil solutions are illustrated briefly.     

Chemical separation and inductively coupled plasma–atomic emission spectrometric determination of seventeen trace metals in thorium oxide matrix using a novel extractant – Cyanex-923

Comprehensive studies have been carried out on the extraction behaviour of thorium matrix vis-a-vis 17 trace metallic elements using a novel extractant viz. Cyanex-923. The near total extraction of thorium and quantitative separation of these metals has been established using inductively coupled argon plasma–atomic emission spectrometry (ICP–AES). The recovery of few representative elements has been confirmed by radio-active tracer studies. The studies carried out here have enabled determination of μg/l amounts of all analyte elements with a precision of better than 1% RSD with prior chemical separation from as low as 1 g thorium sample in just five chemical extractions.     

Beer Digestions for Metal Determination by Atomic Spectrometry and Residual Organic Matter

Many standard and official sample digestion procedures for trace metal determination are carried out in open vessels on hot plates. A new procedure for the determination of trace metals by flame atomic absorption spectrometry or inductively coupled plasmaatomic emission spectrometry in beer samples was developed to be performed in closed reactors assisted by microwaves. The results are compared with the ones obtained by other procedures by means of the analysis of the variance. The differences between the procedures are attributed to residual organic matter. Voltammetry, absorption molecular spectrophotometry and high pressure liquid chromatography with a photodiode array detector are used to study the nature of these residues. Nitrobenzoic acids, phenolic acids and other organic compounds are often present after digestion. The results obtained are related to the precision in metal determination by atomic spectrometry. The need for elaboration of certified reference materials for trace metals in beer is suggested.     

Spectrophotometric Determination of Trace Amounts of Molybdenum in Steel and Pure Iron with a New Chromogenic Reagent Dimethoxyhydroxyphenylflurone

ABSTRACT

A simple method for the direct determination of trace molybdenum in low alloy steel and pure iron with selectivity and sensitivity is reported. In the presence of TritonX-100 and sulphuric-phosphoric acid medium, a new chromogenic reagent dimethoxyhydroxyphenyl-flurone (DMHPF) forms a red complex with molybdenum(VI). The molar absorptivity is obeyed from the range of 0? 8 μg/25 ml for molybdenum(VI). Most of metal ions and 35000-fold amounts of iron do not interfere with the determination of molybdenum. The proposed method has been successfully used for the determination of trace amounts of molybdenum in steel and pure iron specimens.     

Steel surface processing by a continuous optical discharge plasma

The influence of a continuous optical discharge (COD) plasma generated in flowing argon and argon-nitrogen mixture on alloy and carbon steel surfaces has been investigated. Changes in the structure, element composition, and microhardness of steel surface layers under the action of a COD plasma and laser beam were observed. In the presence of a COD plasma the microhardness distribution in hardened zone reaches its maximum at the metal surface and is different from that measured for samples processed by laser beam only.