Characterization of high-purity aluminium

Summary The state of the art in characterization of high-purity aluminium, including activation analysis, glow discharge mass spectrometry (GDMS) and wet chemical multistep procedures has been described. It has been shown on the basis of comparative tests, in which laboratories in Europe, Japan and USA have participated, that with regard to power of detection as well as reproducibility even at levels below 500 ng/g neutron activation analysis (INAA, RNAA), wet chemical multistep procedures and GDMS can contribute to the characterization of high-purity aluminium. The measurement of the resistivity ratio have proved as a suitable test for the integral content of dissolved impurities. H at levels of 0.3 g/g can be measured by vacuum solid extraction or carrier gas fusion. For a complete and optimal characterization of high-purity aluminium all these methods are needed and should periodically be checked against each other.

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Charakterisierung von hochreinem Aluminium

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Thanks are expressed to VAW High-Purity Metal Division for allowing of publishing the foregoing results and financial support.     

Extraction-spectrophotometric determination of thallium in high-purity indium

Trace amounts of thallium in high-purity indium are separated from the matrix by extraction from 6M hydrochloric acid by di-isopropyl ether. On shaking the extract with Brilliant Green in 0.15M hydrochloric acid, an ion-association complex is formed in the organic phase. Interference of other elements is removed by their reduction with metallic copper and scrubbing. The proposed method permits determination of 10(-5)-10(-6)% thallium in high-purity indium with good precision and accuracy.     

Development of certified reference materials of high-purity volatile organic compounds: purity assay by the freezing-point depression method

For accurate measurement of concentrations of substances by instrumental analysis, reliable calibration standards are needed. In Japan, national reference materials are supplied under the national standards dissemination system named the Japan Calibration Service System (JCSS). In JCSS, calibration standards for the analysis of environmental pollutants are supplied. For the traceability to the SI of reference materials for calibration in JCSS, the National Metrology Institute of Japan (NMIJ) is developing high-purity reference materials of volatile organic compounds (VOCs) as NMIJ CRMs. The freezing-point depression method, which has potential as a primary method of measurement, is employed for the determination of property value. In this paper, a development scheme of certified reference materials of high-purity VOCs is described. Presented at BERM-11, October 2007, Tsukuba, Japan.     

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.     

Substoichiometric and non-destructive determination of trace impurities in high-purity optical glasses by neutron activation analysis

A method of radioactivation analysis has been developed for the determination of 17 elements as impurities in high-purity optical glasses. The substoichiometric extraction of platinum with dithizone was studied and a simple procedure was proposed for the determination of platinum. Copper and manganese were also determined substoichiometrically by the extractions with dithizone and with thenoyltrifluoracetone, respectively. The non-destructive γ-ray spectrometry using a Ge(Li) detector has been applied for the determination of the other 14 elements (Ag, Co, Cr, Eu, Fe, Ir, Sc, Zn, Cs, Hf, Rb, Sb, Ta and Tb). Impurity elements at the ppb level were analysed by the proposed method and it is shown that the method is reliable for the determination of trace impurities in high-purity optical glasses.     

Analysis of high-purity material—A comparison of photon activation analysis with other instrumental methods

Photon activation analysis (PAA) has been a well-established analytical method for about two decades. In this paper, its particular features are outlined in comparison with other modern instrumental techniques, especially radioanalytical methods, e.g. activation analysis with thermal or fast neutrons (NAA) or charged particles (CPA). Emphasis is placed upon the determination of trace components of high-purity material; iron, copper and lead matrix were selected as examples. In PAA, both instrumental and radiochemical procedures were applied. The results are presented in comparison with those obtained by other laboratories using a large variety of different techniques.     

Determination of the main component in high-purity organic substances: Current status and prospects

The current status of the determination of the purity of high-purity organic substances using direct and indirect chromatographic methods is discussed. It is shown that the results of the chromatographic determination of the main component in high-purity organic materials are generally ambiguous and unreliable. The possibility of determining the purity of organic compounds using an elemental analyzer of C, H, and N without involving standard samples of analytes is examined; the advantages and drawbacks of this approach are discussed. It is demonstrated experimentally by the example of several nitrogenated compounds that the main component can be determined with an error no worse than 0.6 rel. %, whereas the error of element (nitrogen) determination in the molecule does not exceed the permissible error of elemental analysis.     

Chromatographic behavior of epirubicin and its analogues on high-purity silica in hydrophilic interaction chromatography

Hydrophilic interaction chromatography has been applied for the separation of epirubicin and its analogues using high-purity silica column with aqueous-organic mobile phase. Parameters affecting the chromatographic behavior of the solutes such as organic modifier, buffer pH, ionic strength and sample size, have been investigated. Of utmost importance for successful separation of these analogues is the choice of organic modifier, since it impacts both the solvent selectivity and the ionization of silica silanols as well as buffer solution, and consequently the retention behavior of solutes. Acetonitrile was shown to offer superior separation of these analogues to methanol, isopropanol or tetrahydrofuran. Results of the effects of organic modifier, buffer pH and ion strength indicate that the retention mechanism is a mixed-mode of adsorption and ion exchange. In addition, an irreversible adsorption of these compounds was found on silica in the weakly acidic or neutral mobile phases, and the effect of various factors on irreversible adsorption was also preliminarily discussed. More significantly, these basic compounds have exhibited peaks with a slanted front and a sharp tail, a typical overloading peak profile belonging to the behavior of competitive anti-Langmuir isotherm by increasing the sample size at the experimental conditions.     

Trace analysis of high-purity iron by total reflection X-ray fluorescence spectrometry

Summary A combined procedure enabling simultaneous multielement analysis of trace impurities in high-purity iron is presented. After removal of the iron matrix by solvent extraction with methyl isobutyl ketone, the trace elements Ti, V, Cr, Mn, Ni, Cu, Pb and Bi are determined by means of total reflection X-ray fluorescence analysis. Detection limits are found in the range of 100 ng/g. The reliability of the method is verified by the analysis of commercial high-purity iron and by the comparison of analytical data obtained by ICP-AES.     

Isotope dilution mass spectrometry of microelectronically relevant heavy metal traces in high-purity cobalt

Summary Because cobalt and its silicides are increasingly used in microelectronic devices, an isotope dilution mass spectrometric (IDMS) method has been developed for trace analysis of relevant heavy metals (U, Th, Fe, Zn, Tl, and Cd) in high-purity cobalt. The measurements of the isotope ratios were carried out with a small thermal ionization quadrupole mass spectrometer by producing positive thermal ions in a single- or double-filament ion source. For the trace/matrix separation and the isolation of the different heavy metals, anion-exchange chromatography and an extraction method for iron were applied. The detection limits obtained were (in ng/g): U=0.007, Th=0.017, Tl=0.06, Cd=1, Zn=8, and Fe=11, which demonstrates that the particularly critical radioactive impurities uranium and thorium could be analysed down to the low pg/g range. Three cobalt samples of different purity were analysed with concentrations ranging from about 0.1 ng/g for U and Th in an ultra high-purity material produced for microelectronic purposes, up to about 70 g/g for Cd in a cobalt sample with declared purity of 99.8%. Because IDMS usually results in accurate analytical results, it can be used in the future for calibration of other methods like glow discharge mass spectrometry, as could be shown by analysing one cobalt sample by both methods. IDMS can also be applied for the production of urgently needed certified standard reference materials in this important field of high technology.Presented at the ANAKON '93 conference     

Instrumental neutron activation analysis of high-purity gallium,arsenic, and gallium arsenide

Instrumental neutron activation analysis (INAA) has been applied to obtain useful data on impurity concentrations in ultra-pure materials whose matrix elements are strongly activated and create severe interference for several weeks after irradiation. An analytical procedure has been developed and used to determine Sc, Fe, Co, Zn, Se, Zr, Ag, In, Sn, Sb, Te, and Hg in high-purity gallium, arsenic, and gallium arsenide. Detection limits ranged from 50 ng/g for iron to 0.001 ng/g for scandium. Problems of contamination control, blank level, and standardization are discussed.     

Determination of impurities in high-purity solvents by neutron activation analysis

The determination of impurities in high-purity solvents, (acetone, isopropanol, trichloroethylene and trichlorotrifluoroethane) used in the production of integrated circuits was carried out by reactor neutron activation analysis. A special vacuum evaporation technique was used for the preconcentration of the solvents. The results showed that sodium and iron are the main impurity components in the solvents and on the other hand the quality of the solvents satisfies the specifications required by high-technology standards. The suspended solid particles in solvents were counted by a Microscopic Image Analysis System (MIAS).     

Trace element determination in high-purity scandium by neutron activation analysis and pre-irradiation matrix separation

A pre-irradiation separation procedure has been developed for the determination of trace elements in high-purity scandium by neutron activation analysis. The sample is dissolved in high-purity concentrated hydrochloric acid and scandium is extracted with the same volume of a solution of 50 vol.% bis(2-ethyl hexyl)-orthophosphoric acid (HDEHP) in toluene. The scandium matrix is removed from the most important trace impurities and the residual amount of Sc is in the range of 0.001%. The separation is carried out in the vial to be used in irradiation to prevent sample contamination. Detection limits in the ppb range were achieved with a sample of 10 mg, a thermal neutron flux of 2 · 10¹³ n · cm^–2 · s^–1 and an irradiation time of 48 hours. Most of the elements sought in two samples of high-purity scandium were below the detection limits.     

The analysis of high-purity noble metals and their salts by ICP-MS

Ongoing work is being carried out at Mintek to establish methods for the determination of trace levels of impurities in high-purity noble metals and their salts. The sample-preparation methods are outlined, and the optimum instrumental parameters that were established are tabulated. Spectral interferences arising from the presence of a matrix element at high concentration levels, including abundance sensitivity overlap and the formation of noble-metal oxides, are discussed. Accuracy was established by the comparison of the results with those obtained by a DC-arc method, and by spike recovery tests. The precision of measurement was found to vary from 0.72 to 49% S(r) for concentrations of between 15 and 0.5 gmg/g, respectively.     

Comparison of methods for the determination of ultra-trace amounts of arsenic in high-purity trichlorosilane by NAA and AAS

Neutron activation analysis has been applied to the determination of ultra-trace amounts of arsenic based on the substoichiometric extraction of As(III) with thionalide. The arsenic content in high-purity trichlorosilane or silicon can be determined by the proposed method down to sub-ppb range with a very good reproducibility. Also, the data obtained were compared with results from atomic absorption spectrophotometry.     

Determination of impurities in high-purity gold, with a gas-stabilized low-temperature arc

A gas-stabilized arc with aerosol supply has been used for emission spectrometric determination of Al, B, Be, Co, Cr, Fe, Ga, In, Mg, Mn, Ni, Pd, Rh and Zn, as impurities in high-purity gold. Two analytical procedures were compared: (a) direct aspiration of dissolved samples containing 2% of gold and 0.25M KCl as buffer, and (b) separation of impurities by ether extraction of gold from 1M HCl followed by impurity determination with a stabilized arc. Limits of detection, precision and recovery of the extraction procedure are given.     

辉光放电质谱法测定高纯材料中痕量硫杂质

准确测定并控制材料中杂质元素含量是发挥高纯材料性能不可或缺的环节。辉光放电质谱法(GDMS)是准确、快速、高灵敏分析高纯材料中痕量及超痕量硫的理想方法。对GDMS分析高纯铜和镍基高温合金中痕量硫的质谱干扰进行了讨论,优化了放电电流和放电电压,采用多种标准物质对硫的相对灵敏度因子(RSF)进行了校准和验证,并与二次离子质谱法(SIMS)进行分析结果比对,验证了GDMS定量分析结果的准确性和可靠性。     

Synthesis of high-purity trialkylgermanethiols

A procedure was developed for preparing high-purity trialkylgermanethiols by the reaction of hexaalkyldigermoxanes with hydrogen sulfide.     

Laser-ultramicroscopic method of determining suspended particles in high-purity liquids

Two main types of impurities in high-purity liquids have been determined. One consists of suspended particles of sub-mum size, and optical counters are the most suitable for their determination. Their main characteristics are given. The errors of suspended particle determination are discussed. The data on particles dispersion composition and concentration in some high purity liquids as well as on their nature are given.     

The wet chemical analysis of certain impurities in high-purity beryllium

Photometric methods for the analysis of iron, nickel, copper, aluminum, silicon, chromium and manganese in high-purity beryllium are described.