Internal standard method utilized for 14 MeV neutron induced characteristic X-ray emission analysis

The instrumental neutron activation analysis technique (INAA) was used for homogeneity tests and certification analyses of the coal fly ash reference material ECO prepared at the Institute of Radioecology and Applied Nuclear Techniques (IRANT), Koice, Czechoslovakia. The relative standard deviations due to inhomogeneity were found to be <3% for 19 elements including for sample weights about 50 mg. The results of determination of the elements Al, As, Ba, Ca, Ce, Co, Cr, Cs, Dy, Eu, Fe, Ga, Hf, In, K, La, Mn, Mo, Na, Nd, Ni, Rb, Sb, Sc, Sm, Sr, Ta, Th, Ti, U, V, W, and Zn, were compared with the IRANT certified or information values. Inference was made on the reliability of the IRANT specified values for the element contents.     

Homogeneity tests and certification analyses of coal fly ash reference materials by instrumental neutron activation analysis

The instrumental neutron activation analysis technique (INAA) was used for homogeneity tests and certification analyses of coal fly ash reference materials ENO, ECH, and EOP prepared at the Institute of Radioecology and Nuclear Techniques (IRANT), Koice, Czechoslovakia. Quantitative estimation of a degree of inhomogeneity was suggested. The relative standard deviations due to inhomogeneity were found to be <1% for macroconstituents and <3% for minor and trace elements for sample weights about 25 mg. The results of determination of the elements Al, As, Ba, Ca, Ce, Co, Cr, Cs, Dy, Eu, Fe, Ga, Hf, In, K, La, Mn, Na, Nd, Ni, Rb, Sb, Sc, Sm, Sr, Ta, Th, Ti, U, V, W, and Zn were compared with the IRANT certified or information values. NBS SRM 1633a Trace Elements in Coal Fly Ash was also analyzed as a control sample and the results for the above elements were compared with the NBS certified, information or literature available values. From these comparisons, inference was made on the quality of the IRANT specified values for the element contents.     

Evaluation of homogeneity of selected reference materials for selenium by cyclic neutron activation analysis

The homogeneity of four reference materials was evaluated for Se by cyclic instrumental neutron activation analysis (CINAA). The relative standard deviation for Se measurements at ppb levels by CINAA was <12% for NIST Wheat Flour (SRM 1567) in 5–10 mg samples, while it was <11% for Chinese Hair (HH–CH-1), <13% for IAEA Animal Muscle (H-4) and 25% for IAEA Animal Blood (A-13) in 50 mg samples. The highest relative subsampling uncertainties were observed in the mass range of samples 50 mg for Chinese Hair, 100 mg for Wheat Flour and Animal Muscle and 300 mg for Animal Blood. The results of a one-way analysis of variance indicate that all reference materials above these mass ranges are adequately homogeneous with respect to Se distribution. Our data suggest that these materials, except Animal Blood, can be used as reference standards for Se in Quality assurance programs well below the sample masses re commended by the issuing agencies.     

Bestimmung von Fluor in Knochen durch Neutronen- und Photonenaktivierungsanalyse

Zusammenfassung Im Rahmen eines Methodenvergleiches wurde der Fluorgehalt identischer Knochenproben durch Neutronen (NAA)- und Photonen (PAA)-Aktivierungsanalyse untersucht. Nach Optimierung der Bestrahlungs- und Me\bedingungen ergibt sich als Nachweisgrenze bei der NAA 3,9 g und bei der PAA 0,3 g. Diese Nachweisgrenzen sind ausreichend, um in einer Knochenbiopsie der Masse 50 mg den minimal zu erwartenden Fluorgehalt von 200 ppm quantitativ zu bestimmen. Der Analysenfehler betrÄgt in diesem Fall bei der NAA ±15% und bei der PAA ±25%. Der Zeitaufwand für die Analyse einer Einzelprobe betrÄgt 1 min (NAA) bzw. 4 h (PAA). Die Regressionsanalyse ergibt einen Korrelationskoeffizienten von 0,96.

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Determination of fluorine in bones by means of neutron and photon activation analysis

For comparison of the two methods the fluorine content was determined in identical bone samples. After optimization of the irradiation and measuring conditions the detection limit was found to be 3.9 g for NAA and 0.3 g for PAA. Both detection limits are sufficient for the quantitative determination of the minimum expected value of 200 ppm fluorine in a bone biopsy sample of 50 mg. In this case the analytical error is ±15% for NAA and ±25% for PAA, respectively. The time necessary for the analysis of a single sample is 1 min (NAA) or 4 h (PAA). The regression analysis yields a correlation coefficient of 0.96.

     

Characterization (certification) of three wheat flours and a wheat gluten reference material (NIST RM 8436, 8437, 8438 and 8418) for essential and toxic major, minor and trace element constituents

Summary Three wheat flours, Durum Wheat Flour (NIST RM 8436), Hard Red Spring Wheat Flour (NIST RM 8437), Soft Winter Wheat Flour (NIST RM 8438) and Wheat Gluten (NIST RM 8418) Reference Materials were characterized for essential and toxic major, minor and trace elemental composition by analysts in an interlaboratory cooperative characterization campaign. Extensive application of widely varied analytical methods yielded 16–27 best estimate and 3–8 informational concentration values for each of these materials. These reference materials are intended for analytical quality control of element determinations in flour and flour products as well as other agricultural/food materials with related matrices.Contribution No. 92–145 from Centre for Land and Biological Resources Research     

Chemical Reactions of Surfactants with Acid–Base Dyes and Determination of Imidazolines in the Air of the Working Area

Reactions of acid–base monoazo dyes with polyamine surfactants were studied. The ratios of components in the resulting compounds were determined; the stability constants and molar absorptivities were calculated. A mechanism was proposed for the reaction of monoazo dyes with amine and imidazoline surfactants with the formation of macroheterocycles. Approaches to predicting analytical reactions between monoazo dyes and surfactants were substantiated. The dependence of the extraction of these compounds on the pH of the aqueous phase and the concentrations of NaCl and ethanol was studied. The optimal conditions for extraction separation were found, and a procedure was developed for the spectrophotometric determination of 1-(-hydroxyethyl)-2-heptadecenyl-2-imidazoline (Imidazoline 17) and 1,1"-bis(-hydroxyethyl)-2-heptadecenyl-2-imidazolonium chloride (Imidastat O) in the air of the working area using Methyl Orange as the reagent. The determination limits were 0.025 and 0.12 g/mL, respectively. A sampling procedure was developed for the determination of Imidazoline 17 and Imidastat O in the air with determination limits of 0.05 and 0.25 mg/m³, respectively, for sampling 15 L of air to 60% ethanol.     

Optimization of information properties of NAA with respect to information content and profitability of results

Information properties of analytical results together with other important parameters especially economic ones can be used for the optimization of analytical procedures. Therefore, we have proposed a computational technique for the optimization of multielement neutron activation analysis (NAA) based on the information content and profitability. The optimization starts with the prediction of the -ray spectra to be expected during analysis under given experimental conditions (sample size, irradiation, decay and counting times etc.) and with the calculation of detection and determination limits. In the next step, the information contents for the determination of particular elements and for the simultaneous determination of element groups are computed. The information content depends or is closely connected with such properties of the method as selectivity, sensitivity, precision, accuracy and, as in the other cases of trace analysis, also with the detection limit. Then, the information profitability (IP) taking into account the information content and relevance (appreciation of specific information according to its contribution to the solution of a given problem) together with economic aspects can be calculated. This function can be used for the optimization of a particular NAA procedure, for the mutual comparison of different variants of NAA and also for the comparison with other analytical methods. The use of information profitability for the optimization of NAA is shown on a practical example of the INAA analysis of urban particulate matter SRM 1648 produced by NBS (USA).     

Classical analysis including trace-matrix separation versus solid state mass spectrometry: A comparative study for the analysis of high purity Mo,W and Cr

The applicability of GDMS, SIMS, SSMS, NAA and TMS with AAS, ICP-OES and ICP-MS end determination for routine bulk ultratrace analysis of high purity refractory metals was investigated. Due to the heterogeneous distribution of trace elements in the sub-ppm range, sample consumption and analysis time have a tremendous influence on quantification with procedures of low sample consumption. As an example, GDMS, which is commonly used for ultrapure material certification by most of the manufacturers in Europe and the USA, exhibits discrepancies by more than one order of magnitude for repetitive analyses of a series of trace components in the same sample. Furthermore, results of different laboratories using the same instrument are frequently not comparable. Due to easy standardization and large sample consumption TMS procedures combined with FAAS, GFAAS, ICP-AES and ICP-MS as methods of end determination exhibit better precision and accuracy than GDMS and SIMS. Detection limits are comparably low or even better in case of ICP-MS end determination. TMS procedures are less expensive and less time consuming than highly sophisticated analytical techniques like GDMS, SIMS or NAA. Additionally, they can be easily applied by experienced personnel in a well equipped industrial analytical laboratory.List of Acronyms Used AAS Atomic Absorption Spectrometry - FAAS Flame Atomic Absorption Spectrometry - GDMB Gesellschaft Deutscher Metallhütten- und Bergleute - GDMS Glow Discharge Mass Spectrometry - GFAAS Graphite Furnace Atomic Absorption Spectrometry - ICP-AES Inductively Coupled Plasma Atomic Emission Spectrometry - ICP-MS Inductively Coupled Plasma Mass Spectrometry - IDMS Isotope Dilution Mass Spectrometry - NAA Neutron Activation Analysis - SIMS Secondary Ion Mass Spectrometry - SSMS Spark Source Mass Spectrometry - TMS Trace-Matrix Separation - VLSI Very Large Scale Integration - XRFS X-Ray fluorescence Spectroscopy Dedicated to Professor Günther Tölg on the occasion of his 60th birthday     

Elemental analysis of special materials by X-ray fluorescence spectrometry

The special materials like phosphor bronze for P, Fe, Ni, Cu, Zn, Sn and Pb; mild steel for P, S, V, Cr, Mn, Co, Ni, Cu, As, Nb, Sb and W; special alloys for Ti and Mo, zircaloy and zirconium oxide for Hf; and zircon ore for Zr have been analyzed by X-ray fluorescence spectrometry (XRFS). The measured values along with certified values, precision and accuracy have been given for all the elements analyzed. Some of these materials have also been analyzed by atomic absorption spectrometry (AAS), neutron activation analysis (NAA) and inductively coupled plasma emission spectrometry (ICP-ES). The analytical data of XRFS are in agreement with the results obtained by AAS-ICP-ES and NAA. In most cases the precision is within ±2% and accuracy is ±4%. The precision and accuracy for S, P, Ni and Hf are poor at low concentrations. Practical low detection limit of about 40 g/g of Hf in zirconium matrix has been achieved. It is established that precise and accurate determination of Ti and Mo in special alloys is possible using XRFS.     

Lability of the β-diethylaminoethyl group under the conditions of the formation of a pyrrole ring via the Knorr synthesis

The corresponding 3-acetyl- and 3-H-pyrroles are formed along with 2,4-dimethyl-3-(-diethylaminoethyl)-5-carbethoxypyrrole in the condensation of 3-(-diethylaminoethyl)pentane-2,4-dione with isonitrosoacetoacetic (I) and isonitrosomalonic (II) esters.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1643–1645, December, 1973.