Development of activation techniques for extensive requirements in uranium and multielement analysis

A new neutron activation technique based on cyclic activation combined with intermediate temporary sample storage and special data processing has been developed by use of the modified nuclear analyzer at N.R.C. Demokritos for accurate determination of uranium with relative standard deviation less than 0.05% and for the reduction of matrix interference by further timing optimization in non-destructive instrumental multielement analysis.     

Development of EDXRF techniques for the quantitative multielement analysis of urban dust samples

Summary The investigation and monitoring of suspended particulate matter in air require accurate and sensitive multielement analysis of large numbers of samples. In the work described, airborne particles and settled urban dusts were examined by energy dispersive X-ray fluorescence spectrometry with secondary-target excitation. The practical requirements of trace-element determinations in dusts are reasonably satisfied by two techniques. Deposition of fine particles (under 3.5m) on Nucleopore membrane filters provides thin-film samples, for which absorption and particle-size effects are usually negligible. Calibration is achieved by sputtering of certified NBS standard glasses onto membrane filters. In the destructive fusion and direct solidification technique, sample inhomogeneities and particle-size effects are eliminated by fusing the sample with lithium borate in a Pt/Au alloy crucible. La₂O₃ or WO₃, added as heavy absorbers, can reduce the interelement-effects of the thick specimens to a certain extent. A newly developed computer program, based on a modified mathematical expression for the intensity, compensates for absorption and secondary fluorescence effects. It is demonstrated that for some trace elements the background can be easily predicted as a linear function of the incomplete charge-collection of the Si(Li) detector. An intermethod comparison with atomic-absorption results is presented; the results are verified with the NBS Fly Ash standard reference material.

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Zusammenfassung Die Untersuchung und Überwachung luftgetragener, feiner Stäube erfordert eine hinreichend genaue und empfindliche Multielement-Analysen-methode, die eine schnelle Bestimmung von Serienproben ermöglicht.Es wird über die Untersuchung luftgetragener Staubteilchen und sedimentierter Stadtstäube mittels energiedispersiver Röntgenfluoreszenzspektrometrie mit Sekundärtargetanregung berichtet. Den praktischen Anforderungen einer Spurenbestimmung in umweltrelevanten Staubmatrices wird dabei durch folgende 2 Methoden entsprochen.Feine luftgetragene Staubteilchen unter 3,5m werden auf Nucleopore Membranfilter abgeschieden und direkt mittels EDXRF zerstörungsfrei gemessen. In diesen quasi unendlich dünnen Schichten sind Matrixeffekte und Teilchengrößeneffekte praktisch zu vernachlässigen. Die Eichung erfolgt mittels dünner Schichten, die durch Sputtering von NBS-Gläsern mittels Argon-Ionenstrom hergestellt werden.Werden die Proben mit Li₂B₄O₇ in einem Pt/Au-Tiegel zu homogenen glasartigen Scheibchen geschmolzen, so lassen sich alle Inhomogenitätsund Teilchengrößen-Effekte, die eine Analyse stören, vermeiden. La₂O₃ oder WO₃, den Proben als schwerer Absorber zugesetzt, reduziert die Interelementeffekte der praktisch unendlich dicken Proben. Es wird über ein neu entwickeltes Computerprogramm zur Datenreduktion berichtet, das nach der theoretischen und empirischen Methode für Absorptionsund Interelementeffekte korrigiert. Es wird gezeigt, daß für einige Spurenelemente der Untergrund eine lineare Funktion der incomplete charge collection des Si-(Li-)Detektors ist und auf empirischem Wege einfach berechnet werden kann.Abschließend wird ein Methodenvergleich mit der AAS präsentiert; die Ergebnisse werden mit dem Standardreferenzmaterial NBS Fly Ash verifiziert.

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Presented at the International Symposium on Microchemical Techniques, Davos, May 1977.

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This work was done when K. E. Lorber was at the National Bureau of Standards.     

The yields of photonuclear reactions for multielement photon-activation analysis

A comprehensive study on the yields of photonuclear reactions of various types has been performed, and sensitivities and the effects of interferences in multielement photon-activation analysis have been evaluated by bremsstrahlung activation of many elements with maximum energies ranging from 30 to 60 MeV. The applicability and reliability of the method were demonstrated by analyzing standard round-robin samples and then by presenting the elemental abundances in several geological, biological and environmental materials. The method was almost insensitive to matrix effects and was assessed to be promising for nondestructive multielement determination of the materials of wide variety, giving good reproducible results for 20 or more elements.     

Utilization of microflow reactors to carry out synthetically useful organic photochemical reactions

This review focuses on recent advances that have been made in conducting synthetically useful organic photochemical reactions by using microflow reactors. Attention is given to the utilization of this technique in the “scale-up” of a variety of photochemical processes including intermolecular photocycloadditions, intramolecular photocycloadditions and photocyclizations, photoadditions, photoreductions, photoisomerizations, photosubstitutions, photooxidations, photorearrangements, and heterogeneous photocatalytic reactions. In many examples, the use of the microflow method is compared to those carried out in batch systems. Finally, advantages and disadvantages of microflow photoreactions along with the possible employment of this approach to scale-up industrial photochemical processes are discussed.     

Development of a solid phase extraction method for the multielement determination of trace metals in natural waters including sea-water by FI-ICP-MS

An automated solid phase extraction method by flow analysis on-line inductively coupled plasma mass spectrometry (FI-ICP-MS) for the determination of cobalt, chromium, nickel, cadmium, manganese, zinc, copper and lead in sea-water and other natural waters is described. The system is based on retention of the analytes onto a minicolumn packed with a chelating resin, 1,5-bis (2-pyridyl)-3-sulphophenyl methylene thiocarbonohydrazide immobilized on aminopropyl-controlled pore glass, placed in the injection valve of a simple flow manifold. The effects of chemical and flow variables were investigated and selected as a compromise between sensitivity and sampling frequency. So, the sample solutions (adjusted to pH 8.0 ± 0.5) were passed through the column. After washing the column with water, the adsorbed metals were subsequently eluted into the plasma with 4% m/m nitric acid. Detection limits of the trace metals (180 s sample loading time at a sample flow rate of 0.7 mL min^? 1; sampling frequency 8.6 h^? 1) were 0.002 μg L^? 1 for Co, 0.057 μg L^? 1 for Cr, 0.117 μg L^? 1 for Ni, 0.004 μg L^? 1 for Cd, 0.210 μg L^? 1 for Mn, 0.260 μg L^? 1 for Zn, 0.030 μg L^? 1 for Cu and 0.020 μg L^? 1 for Pb, with enrichment factors between 2.2 and 6.8. The accuracy of the proposed method was checked with certified reference materials (CRMs) of sea-water SLEW 3, LGC6016 and CASS-5, river water SLRS-5 and fortified lake water TMDA-54.4. The results from the determination of these metals were in agreement with the certified values and recovery values ranged between 92.2 and 110.6%. The method was applied to the determination of these metal ions in sea-water samples collected in the Málaga Bay in order to realize a pilot study necessary to generate preliminary information on which to base a more detailed pollution study by heavy metals of the Bay.     

Two-dimensional multiple entrance-slit vidicon spectrometer for simultaneous multielement analysis

A new type of wavelength dispersion system for use with a multichannel detector has been developed for simultaneous multielement analysis. The system employs a monochromator with fixed grating position, and incident angle varied by horizontal displacement of the entrance slits. The overlapping spectral windows which result can be arranged to produce a composite spectrum having minimal interference from emissions by other sample constituents. Entrance slits may also be displaced vertically to create a two-dimensional system in which spectra are stacked one above the other and scanned by use of a multi-raster scanning pattern. A number of optical and performance characteristics of the system are evaluated in both the one- and two-dimensional modes, and the system is applied to the determination of Ca, Na and K in blood serum and to the determination of the exchangeable cations Ca, Na, Li and K in clay. The advantages of this system for simultaneous multielement analysis are discussed.     

A comparison of synthetic irradiation-resistant multielement standards for activation analysis

An aluminium matrix and a phenolformaldehyde polymer were tested as base materials for multielement standards resistant to high neutron doses in activation analysis. Interlaboratory analyses showed that these standards can be certified for the concentrations of the majority of introduced elements.     

Simultaneous multielement atomic-absorption analysis of biological materials

A prototype multielement atomic-absorption spectrometer (SIMAAC) consisting of a continuum source and an echelle polychromator modified for wavelength modulation, has been used to determine several elements in a variety of biological materials. Analyses have been done with flame atomization as well as graphite furnace atomization. Compromise atomization conditions do not significantly limit the accuracy or precision. Analytical results for a variety of samples are reported.     

Operation and application of a laser mass analyser (LASMA) for multielement analysis

The design and the operation of the LASMA instrument combining laser ablation with time-of-flight mass analysis is briefly described. The application to the analysis of multielement metal samples and non-conducting powder mixtures of known composition reveals the LASMA technique to be a semi-quantitative method for elemental bulk analysis with a detection limit around 50 μg/g in a mass range up to 250 amu.     

Influence of additives on the main performance parameters of a multielement spectrographic method for powder analysis using a free-burning d.c. arc

The influence of various spectrochemical additives with different effects on the most important evaluating parameters of spectrographic powder analysis was investigated on the basis of model experiments. Two main groups of additives were used for the study: one with the same cation and varying anions, and one with the same anion and varying cations.The kinetics of evaporation (particularly the role of high resistance carbon electrodes), the reproducibility of sample introduction (evaporation) and excitation, furthermore the analytical calibration, detection power and accuracy were studied.     

Use of Lewis acids and high pressure to carry out extremely hindered Diels-Alder reactions

Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 3, pp. 743–744, March, 1989.     

New Polish certified reference materials for multielement inorganic trace analysis

Summary An overview of the activities of the Polish Institute of Nuclear Chemistry and Technology in the field of preparation and certification of reference materials for multielement trace analysis is presented. A general strategy has been worked out and is briefly described with more detailed emphasis on the problem of data evaluation. Two geological-environmental materials recently issued [i.e. an Apatite Concentrate (CTA-AC-1) and Fine Fly Ash (CTA-FFA-1)] which were certified for 25 and 40 elements, respectively, are described. The preparation and testing of a new CRM of biological origin Oriental Tobacco Leaves (CTA-OTL-1) is presented in detail, including study of the optimum methods for drying, checking homogeneity, radiation sterilization etc. Interlaboratory comparison, in which 61 laboratories participated, yielded results enabling recommended (certified) values for 29 elements and information values for further 11 elements to be established.     

Development of a sensitive MEKC-LIF method for synthetic cathinones analysis

Synthetic cathinones are phenylalkylamine compounds related to natural cathinone from Catha edulis leaves. Due to their sympathomimetic effects comparable to common illicit drugs, these substances are mainly drugs of abuse and constitute the second most frequently seized group of new psychoactive substances. In order to ensure their regulation and to promote public health, reliable analytical tools are required to track these substances. In the present study, we developed a CE hyphenated to laser-induced fluorescence detection method to demonstrate its suitability to perform fast and cost-effective synthetic cathinones analysis. Fourteen compounds including isobaric compounds and position isomers were selected to encompass the large panel of chemical structures. To separate the FITC-labeled analytes (presenting the same negative charge and close mass to charge ratios), MEKC separation mode was selected. Method selectivity was not suitable using common surfactants. In this context, alkyl polyethylene glycol ether surfactants were successfully used as neutral surfactant to overcome this analytical challenge. The effect of surfactant nature on separation performances and migration behaviors of the analytes was also studied. Optimal BGE composition included 75 mM borate buffer at pH 9.3 and 0.4 mM of C12E10 surfactant. Final MEKC separation conditions were proposed to analyze a large panel of synthetic cathinones. This method helped to reach a sensitivity with LOD from 0.1 to 0.4 nM (pg/mL order).     

Identification of wine provenance by ICP-AES multielement analysis

We have estimated the possibility of identifying the provenance of some natural wines produced in the Krasnodar region. The macro- and microelement composition of wines and soils from the place of grape origin has been used as the classification criterion. The main elements indicating the wine provenance, Al, Co, Cu, Mn, Ti, Zn, Ba, and Rb have been determined by inductively coupled plasma atomic emission spectroscopy. We have revealed the possibility of distinguishing wines by their brand and provenance using pair-wise comparison of the classification function parameters for soils and wines produced from grape grown on those soils.     

Theoretical basis for multielement analysis by coherent forward scattering atomic spectroscopy

A theoretical basis for multielement analysis by coherent forward scattering atomic spectroscopy is discussed. Forward scattering spectra are calculated for various atomic transitions in the Faraday and Voigt configurations. It is shown that the multielement capability of forward scattering stems from spectral response to continuum radiation. Comparison is made with the Zeeman atomic absorption method. An experimental result with a xenon arc lamp is also given.     

Total reflection X-ray fluorescence spectrometers for multielement analysis: status of equipment

Multielement analysis by total reflection X-ray fluorescence spectrometry has evolved during two decades. At present commercial equipment is available for chemical analysis of all types of biological and mineral samples. The electronic industry has also benefited from scientific and technological developments in this field due to new instrumentation to determine contamination on the surface of silicon wafers (the equipment will not be covered in this paper). The basic components of the spectrometers can be summarized as follows: (a) excitation source; (b) geometric arrangement (optics) for collimation and monochromatization of the primary radiation; (c) X-ray detector; and (d) software for operation of the instrument, data acquisition and spectral deconvolution to determine the concentrations of the elements (quantitative analysis). As an optional feature one manufacturer offers a conventional 45° geometry for direct excitation. Personal communications of the author and commercial brochures available have allowed us to list the components used in TXRF for multielement analysis. Excitation source: high-power sealed X-ray tubes, output from 1300 to 3000 W, different mixed alloy anodes Mo/W are used but molybdenum, tungsten and copper are common; single anode metal ceramic low power X-ray tubes, output up to 40 W. Excitation systems can be customized according to the requirements of the laboratory. Detector: silicon–lithium drifted semiconductor detector liquid nitrogen cooled; or silicon solid state thermoelectrically cooled detector (silicon drift detector SDD and silicon-PIN diode detector). Optics: multilayer monochromator of silicon–tungsten, nickel–carbon or double multilayer monochromator. Electronics: spectroscopy amplifier, analog to digital converter adapted to a PC compatible computer with software in a Windows environment for the whole operation of the spectrometer and for qualitative/quantitative analysis of samples are standard features in the production of this instrument. The detection limits reported in the literature are presented; pricing, analytical capability, ease of operation, calibration and optical alignment as well as technical support are also discussed.     

Contribution to the in vitro multielement X-ray fluorescence analysis of human soft tissues

Determination of Mn, Fe, Ni, Cu, Zn and Pb in human soft tissues by radionuclide X-ray fluorescence analysis /using²³⁸Pu and¹⁰⁹Cd sources/ is described.