Determination of impurities in high-purity carbon tetrachloride by gas chromatography-mass spectrometry

The impurities in high-purity carbon tetrachloride (CCl ₄ ) were determined by gas chromatography-mass spectrometry (GC-MS). The use of chromatography of near-saturated vapors allowed the injection of samples up to 1 μL into a capillary column and to achieve specific column efficiency in an isothermal mode of 221,000 t.p./m. The detection limits for impurities were 1 × 10⁻¹ to 1 × 10⁻⁸ wt %.     

On the determination of carbon and oxygen impurities in silicon by3He activation analysis

Carbon and oxygen impurities in silicon have been determined by 7.00 MeV³He activation analysis. The detection limits obtained for interference-free conditions are 0.1 ppb (wt) for carbon and 1.0 ppb (wt) for oxygen in silicon.     

Determination of beeswax and some impurities by IR spectroscopy

Summary Analysis of the IR spectra of waxes isolated from samples of paints from paintings dating from the Ist to VIIth centuries of our era and fragments of archaeological antique murals has shown that in some cases the wax isolated is pure beeswax and in others it contains as impurities what are presumably resin acids, and also salts of fatty acids. The IR spectrum of pure beeswax extracted from a fragment buried for 2000 yr is absolutely identical with the spectrum of modern beeswax, which shows the extreme chemical stability of the wax.All-Union Central Scientific-Research Laboratory for Conservation and Restoration, Moscow. Scientific-Research Institute of Organic Intermediates and Dyes, Moscow. Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 271–275, March–April, 1977.     

Infrared study of iron impurities in polycrystalline solar grade silicon

In this work the role of Fe impurities introduced in boron doped polycrystalline solar grade silicon is examined by means of low temperature absorption measurements in the far infrared. In particular, the results can be explained in term of formation of boron acceptor-iron donor complexes.     

Determination of carbon impurities in epitaxial layers from semiconductor silicon by means of charged particles

The energy-dependent range of charged particles in activation analysis according to the reaction¹²C(d,n)¹³N permits the method to be applied to carbon determination in model epitaxial layers of sufficient thickness. We investigated 100 μm epitaxial layers of the n-type and undoped 50 μ layers as to p⁻ Czochralski substrates. Deuterons were slowed down with Cu and Ta foils having a limiting energy of 13.5 MeV, to 4.2 MeV and 2.9 MeV, respectively. In the resulting activation depths of 52 and 102 μm, the sensitivity of the method, which is 3·10¹⁴ at ·cm⁻³C at E_d=10 MeV in silicon, is reduced to 25% and 10%, respectively. An optimal flux of 0.9 μA·cm⁻² was maintained. After irradiation, 20 or 10 μm were etched off. The sample was inductively fused at 1500 K in a Pb₃O₄/B₂O₃ mixture.¹³N was passed with He as carrier gas into an absorption vessel kept at 77 K, and its activity was measured in γ, γ-coincidence.     

Determination of metallic impurities in a silicon wafer by local etching and electrothermal atomic absorption spectrometry.

An etching technique for the determination of the metallic impurities distribution in silicon wafers has been developed. An area of 10 mmphi and 10 microm depth was etched by 100 microL of an etching solution with a HF and HNO3 mixture. The acid matrix was evaporated on the wafer surface by IR lamp illumination and vacuum exhaust. Metallic impurities remaining on the wafer surface were redissolved into the collection solution, which was measured by electrothermal atomic absorption spectrometry (ET-AAS). The recovery invested by local etching/ET-AAS was within 95 - 112% for Fe, Cu and Ni. The detection limit (3sigma) for Fe, Cu and Ni in silicon was 1 x 10(13) atoms/cm3. To confirm the applicability, local etching was applied to evaluate the effects of metallic impurities in a gettering study and the electronic properties of semiconductor devices. It was found that local etching is a useful sample preparation technique for the analysis of metallic impurities in a specific area on a silicon wafer.     

Determination of hydration numbers by IR spectrometry

The use of precision IR spectrometry for determining the hydration numbers of species in organic phase was considered. The hydration numbers of HAuCl₄ (n = 3), HFeCl₄ (n = 3), HNO₃ (n = 0), HClO₄ (n = 2), and HCl (n = 1) in 0.64 M (15 vol. %) TBP in CCl₄ were determined.     

Determination of impurities in silicon carbide powders

Summary The analysis of SiC powders used for the production of high-performance ceramics was investigated by combined procedures as well as by a direct technique including atomic spectrometric detection. For the combined chemical procedure, SiC powders (0.25 g) were completely dissolved in a mixture of HNO₃, HF and fuming H₂SO₄ in an autoclave at 240°C within 8 to 20 h. In the final 0.5% w/v solution 13 elements were determined by electrothermal atomic absorption spectrometry (ETAAS) and by inductively coupled plasma atomic emission spectrometry (ICP-AES). With acid decomposition the detection limits for Ca, Cd, Cr, Cu, Mg, Mn and Zn were found to be in the range of 0.1–1 g/g; those for Al, B, Fe, Ni, Ti and V are at the 1–5 g/g level. With a Babingtontype nebulizer 1% slurries of SiC can be directly analyzed by ICP-AES. Calibration was performed by standard addition of aqueous solutions of the elements to be determined and the detection limits are close to those of ETAAS subsequent to pressure decomposition. The required analysis time was reduced from approx. 24 h to 30 min. First results for Ca, Cr, Cu, Mg, Mn, Ti and V as well as the needs to overcome systematic errors of this method, e.g. for Fe, are communicated.Part of this paper was presented at XI. International Symposium of Microtechniques, Wiesbaden, FRG, Aug. 28th–Sept. 1st 1989     

Determination of lipids and their oxidation products by IR spectrometry

We proposed a procedure for the IR spectrometric determination of lipid hydroperoxides in biological systems. The main bands in the IR absorption spectra of linoleic acid and its hydroperoxide were identified, and analytical bands suitable for the determination of both compounds in their mixtures were selected. It was demonstrated that tert-butyl hydroperoxide can be used as an external standard for determining fatty acid hydroperoxides. Using the external standard method (calibration curve) for tert-butyl hydroperoxides, we calculated the concentration of linoleic acid hydroperoxide in its mixture with linoleic acid; it agreed with the specified values. Using the developed procedure, we estimated the concentration of hydroperoxide groups in natural cardiolipin. The results were compared to those obtained by an independent method (activated chemiluminescence).     

Determination of trace impurities in cobalt by spark source mass spectrometry

An analytical method, SSMS, for the determination of trace impurities in cobalt is described. This element is used as raw material for the production of⁶⁰Co in Embalse Nuclear Power Station. Tin, aluminum, lead, silicon, molybdenum, calcium, vanadium, boron, chromium, zirconium, tungsten, nickel, magnesium, iron, zinc and copper were determined. Manganese, analyzed by AAS, was used as an internal standard. The measurements were semiquantitative. The accuracy of the results was compared with that of emission spectrography and atomic absorption spectrometry, the agreement was found to be satisfactory.     

Determination of trace impurities in cosmetic intermediates by ion mobility spectrometry

The cosmetic and pharmaceutical industries are continuously demanding fast, efficient, cost-effective analytical methods to monitor production processes and assure end-product quality. The presence of residual reagents or impurities formed during a synthetic process can have an adverse impact on product quality, assurance of which requires using increasingly sensitive analytical methods to facilitate the detection and/or determination of toxic compounds with potentially hazardous effects on consumer's health. In this work, we assessed the potential of ion mobility spectrometry (IMS) for the detection and quantitation of dimethylaminopropylamine (DMAPA) residues in stearamidopropyldimethylamine (SAPDA) production samples. The influence of instrumental variables including solvent, solution drying time, injected volume and volatilization temperature was examined. The ensuing analytical method takes less than 1 min per analysis and uses only a few microlitres of sample. The calibration curve was linear over the DMAPA concentration range 0.030-0.500 μg mL(-1). The proposed method was validated for use in control processes. The complex plasmagram for amidoamines allows the origin of cosmetic oils to be easily, expeditiously identified. Based on the results, IMS holds great promise for the qualitative and quantitative determination of the studied amide and various others in cosmetic products.     

Determination of impurities in semiconductor grade silicon by instrumental neutron activation analysis

Instrumental neutron activation analysis has been applied to semiconductor grade silicon to study the concentration levels of impurity elements, the contamination during the single crystal growing process, and the vertical and radial distributions of impurities, along with the decontamination effect in the analysis. Twenty elements of Au, Br, As, W, Cr, Co, Na, Eu, La, Se, Zn, U, Th, Hf, Fe, Sb, Ag, Ce, Tb and Ta have been analyzed in p- and n-type wafers, single crystals and a polycrystal by a single comparator method using two comparators of gold and cobalt. Considerable surface contamination has been found and could be removed by etching the surface with nitric and hydrofluoric acid before and after irradiation. The impurity concentration has been found to be generally increased in the process of single crystal growth. The vertical and radial distributions of impurities have revealed that some impurity elements were more concentrated in the top region of a single crystal rod than in the middle region, and that Br, Cr, La, Eu and Sb were enriched in the central region and As, U and Fe in the outer region.     

Determination of rare earth impurities in ytterbium oxide by X-ray fluorescence spectrometry

Summary Determination of Kare Earth Impurities in Ytterbium Oxide by X-ray Fluorescence Spectrometry An X-ray fluorescence spectrometric method for the determination of traces of Ho, Er, Tm, Lu and Y oxides in the concentration range of 0.005–1% in ytterbium oxide is developed. The precision at various concentrations of the standards is given. Intensity corrections for line overlaps have been determined.     

Determination of silicon in organo-silicon compounds by flame emission spectrometry

Abstract

Optimum conditions for the determination of silicon by flame emission spectrometry were ascertained. The maximum signal emanates from a region immediately above the tip of the inner cone of a fuel-rich oxygen-acetylene flame. The organosilicon compound is aspirated as a solution in ethanol and the emission intensity at 2516.1 Å is measured. Quantitative determinations were made using a working curve and by the method of standard addition. Detection limit is 3.5 μg/ml.     

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 trace impurities in zircaloy-2 and tellurium by spark source mass spectrometry

Determination of trace impurities in zircaloy-2 and tellurium by Spark Source Mass Spectrometry (SSMS) is reported. The advantage of SSMS lies in the fact that along with metallic trace constituents even the nonmetallic impurities and gases including hydrogen can also be determined.     

Determination of hydration numbers of acids in organic phase by IR spectrometry

By the precision infrared spectrometry the hydration numbers n were determined for a series of acids in 0.64 M tributyl phosphate (CCl₄) and acetonitrile at a concentration of free water 0.01–0.1 M. In tributyl phosphate n = 3.1±0.3 (HAuCl₄); 2.9±0.3 (HFeCl₄); 1.9±0.2 (HClO₄); 1.0±0.2 (HNO₃); 1.0±0.1 (HCl). In acetonitrile n = 3.1±0.7 (HAuCl₄); 1.1±0.4 (HFeCl₄); 2.1±0.2 (HClO₄), 0±0.05 (HNO₃); 0.1±0.15 (HCl).     

Determination of impurities in strontium titanate ceramics by inductively coupled plasma mass spectrometry

The determination of impurities in SrTiO₃ by ICPMS was investigated. The sample was decomposed with hydrochloric and hydrofluoric acids in a PTFE pressure vessel. The internal standard method using Au was selected to eliminate an ion count suppression by the Sr and Ti matrix. Impurities at sub g/ml level in SrTiO₃ were determined. The detection limits were in the range of 0.008 to 0.01 g/g.