Multi-element Standards Research Articles

Preparation of trace element reference materials by a co-precipitated gel technique

A method is described for the preparation of trace element reference materials by a co-precipitated gel technique. The technique is applied to the manufacture of multi-element calibration standards for the analysis of geological materials by direct-reading emission spectrometry. The quality of gel reference material is considered in terms of homogeneity, major element and trace element accuracy and purity. Results are presented for the analysis of the gels by a variety of techniques, and for the analysis of international standard geological materials by direct-reading emission spectrometry with gel reference materials calibration.

Low flux multielement instrumental neutron activation analysis in archaeometry

A rouline instrumental method has been developed for theanalysis of 35 elements in potsherds by means of neutronactivation analysis at fluxes of 2 h). This re-striction was necessary because of a physical separation of thelaboratory from the nuclear reactor employed in activationand/or because of the limiting of access to relatively highneutron fluxes in conventional reactors. +It is not impossible to use conventional reactors to deter-mine elements producing short-lived radioisotopes in ceramicmaterials (6), but the extra work required to produce satis-factory results appears to make the task impracticable on aroutine basis.Low flux reactors, such as the SLOWPOKE (Safe LowPower Critical Experiment) reactor at the University of To-ronto (7), allow access to relatively low neutron fluxes(1Qtt-1gtz nlcm2 s) and can be most profitably employed forthe analysis of short-lived isotope-producing elements inpottery.The flux limitations of such a reactor are obvious, but arenot sufficient to eliminate their use for the analysis of elementswhich produce long-lived isotopes. As an example, at theSLOWPOKE reactor, cobalt in potsherds (averages 5-30ppm) may be determined either by the production 6f 6{)mQo(10.5m half-life) or by the production of 6oCo (5.26 yearshalf-life).Since the number of elements previously studied has beenrestricted by analytical technique rather than geological orceramic considerations, a program was instituted to developa more comprehensive multielement analytical scheme whichcould be routinely applied to the analysis of potsherds.Because of the stable nature of the neutron flux in theSLOWPOKE reactor system (8), multielement standards arenot normally employed in the routine analysis o1'samples.The present work described an INAA procedure in which35 elements are quantized for each potsherd. Included areelements indicative of the provenance and the method ofproduction of the ceramics.EXPERIMENTALSamples and Standards. Two Standard Ref'erence Materials. Cloal(SRM 1632) and Fly Ash (SRM 1633), from the U.S. National Bureauof Standards, Washington, D.C., were analyzed as were samples o1'

Non-destructive multi-element photonactivation analysis of environmental materials

A non-destructive method of photon-activation analysis with 30-MeV bremsstrahlung followed by high-resolution gamma-spectrometry has been developed for multi-element determination in ambient air and in air-pollution emissions. The sample materials were the NBS standard reference material. Fly Ash. and atmospheric particulates collected on a Millipore filter. Simultaneous irradiation of the sample with synthetic multi-element standards containing 33 elements has shown that the technique can determine up to 21 elements in a single sample. The method is simple and gives reproducible results.

Multielement photon activation analysis of biological materials

A non-destructive photon activation procedure with 30-MeV bremsstrahlung followed by high-resolution γ-spectrometry is proposed for multielement analysis of biological materials. The materials tested were the NBS SRM Orchard Leaves and Bovine Liver, Bowen′s kale and Kentucky 1R1 tobacco standards. Simultaneous irradiation of the sample with synthetic multielement standards containing 25 elements showed that up to 12 elements can be determined in a single sample. The method is quite simple and gives good reproducible results. Agreement of the results with published data is excellent.

Synthetic multielement standards used for instrumental neutron activation analysis as rock imitations

Complex (multielemental) standards representing microelement composition of standard rocks such as trap ST-1 (USSR), gabbrodiorite SGD-1 (USSR), albitized granite SG-1 (USSR), basalt BCR-1 (USA) and granodiorite GSP-1 (USA) have been synthesized. It has been shown that the concentration of each microelement in the synthetic standards can be given with a high precision. Comparative investigation has been carried out of the synthetic imitations and the above natural standard rocks. It has been found that the result of the instrumental neutron activation analysis using the synthetic standards is as good as in the case when natural standard rocks are used. The results obtained have been also used for substantiation of the versatility of the method used for standard preparation, i.e. a generalization has been made of a possibility of using this method for the preparation of synthetic standards representing the microelement composition of any natural rocks with various compositions and concentrations of microelements.

Some trace element data and their interpretation for several new reference samples obtained by neutron activation analysis

A number of problems associated with the geochemical application of instrumental neutron activation analysis are discussed. Particular emphasis is placed on the problems of preparing and using multi-element standard solutions and/or those associated with the accurate computer reduction of γ-spectral data. It is concluded that accurately and extensively analysed rocks and minerals best fulfil the requirements for multi-element standards in this type of analysis. In the second part of the paper instrumental neutron activation analysis data are presented for 26 international reference samples including 4 of the less well-analysed U.S.G.S. standard rocks. Some limited geochemical interpretations of the data are presented.

Activation analysis of biological material with ruthenium as a multi-isotopic comparator

The elements Fe, Zn, Se, Rb and Co were determined in NBS bovine liver (SRM 1577) by non-destructive activation analysis; ruthenium was used as triple comparator element. The results were compared with the values of the analysis certificate and with those of an analysis based on a multi-element serum standard; the agreement was excellent. The conclusions of the error theory of the comparator method were experimentally confirmed.

A multi-element serum standard for neutron activation analysis

A multi-element serum standard containing the elements Ag, Co, Cr, Cs, Fe, Hg, Rb, Sb, Se and Zn, which is suitable for long irradiations at high neutron flux, is described. Tests showed that the homogeneity of the doped serum is satisfactory even for sample sizes of 20 mg. The accuracy obtainable with the proposed standard was demonstrated by analysis of the N.B.S. SRM 1577 bovine liver.

Nondestructive determination of trace impurities in iron by thermal neutron activation analysis with long-lived isotopes

A method is proposed for the instrumental determination of Co, Cu, W, As, Ga and Sb in a pure iron matrix. Semiconductor detectors with high resolving power, automatic data collection and completely computerized data interpretation have been used. A method of preparing and testing composite multi-element standards is described in detail.

The use of non-destructive high energy gamma photon activation for trace element survey analysis

An empirical study has been made of the potential of high energy γ photon activation and high resolution γ-ray spectrometry for the survey analysis of trace elements in a variety of materials. Human blood, urine, bone ash, standard glass (NBS, SRM 612) and air particulates, along with synthetic multi-element standards, have been studied following irradiation with γ photons of maximum energy 17–45 MeV. Elements found to be suited to determination by γ activation include Sb, As, Bi, Cd, Cs, Ca, Ce, Cr, Fe, Au, Pb, Mg, Mo, Ni, Nb, Rb, Sr, Tl, Ti, Tm, Zn and Zr. γ spectra, elemental concentrations measured, and/or limits of detection observed, for the matrices studied are given.

Multi-element standard for routine instrumental activation analysis of trace elements in rocks and tectites

The use of high-resolution Ge(Li) detectors in non-destructive instrumental neutron activation analysis (INAA) of mineral materials makes possible the simultaneous determination of a number of trace elements. In routine applications of INAA the use of a multi-element standard (MES) has proved to have advantages over a set of standards for each determined element. An MES has been prepared containing 8 trace elements mixed in a suitable proportion and giving, after neutron activation, long-lived γ-emitters, the γ-ray lines of which regularly occur in the γ-ray spectra of silicate mineral materials. This method has been used in the determination of Sc, Cr, Co, Rb. Cs, Eu, Hf and Th in samples of standard rocks and moldavites.