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- Author or Editor: H. Schelhorn x
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Abstract
IAEA standard reference material SOIL-7 has been analyzed by both instrumental NAA and radiochemical NAA using epithermal neutron activation. These analyses confirm the NAA value of Ag in the intercomparison SOIL-7 which disagrees with some AAS values. Further geostandards were included and compared with literature data.
Application of the radioreagent method for yield determination in neutron activation analysis
Determination of copper
Abstract
A very convenient method for yield determination in NAA is the use of isotopic radiotracers. But for the majority of elements determinable by NAA no suitable isotopic radiotracers exist. For some of these elements the radioreagent methodoffers afvourable opportunity to use also non-isotopic radiotracers. An activation analytical copper determination method is described using a radioactively labelled reagent for correction of separation losses. Results of copper determinations in 8 international standard reference materials are given.
Abstract
Sensitive radiochemical procedures for the determination of arsenic in biological samples and silver in geological samples have been developed using77As and111Ag as yield tracers. In connection with this, the yield determination method by means of a radiotracer is discussed, its advantages are demonstrated, suitable tracer nuclides are listed and possibilities to increase their number are proposed.
Abstract
A method for the determination of nickel in ion exchange resins has been elaborated. It is based on the58Ni(n, p)58Co reaction. Samples of 500 mg are irradiated for 90 h in a fission neutron flux of 1013 n·cm−2·s−1. After decomposing by HNO3/HClO4 mixture the radiochemical separation is carried out by extraction of the Co-DDTC-complex in chloroform. Measuring by a 23 cm3 Ge(Li) detector for 15 h provides a detection limit of 10 ppb. Radiochemical yield is determined by57Co as radioactive indicator. Limitations by60Co are reduced by Cd-screened activation and by anticoincidence measuring technique.
Abstract
A neutron activation analysis procedure was developed for the determination of osmium in geological materials. The method consists in the measurement of the 129.4 keV γ-rays of191Os after radiochemical separation of osmium. The sample decomposition, the chemical separation process and the optimal measuring conditions are described and discussed.
Abstract
Neutron activation analysis was used to determine the elements Cu, Mn, As, Cd, Fe, Mo, Zn, Co, Cr, and Se in biological materials. Three different activation analytical techniques were tested by analysing one and the same sample: (1) the instrumental determination, (2) the determination after removal of the major contaminants24Na and32P, and (3) the determination after radiochemical separation. These three techniques are described and the results obtained are discussed. The detection limits determined for each technique are compared.
Abstract
Radiotracers for yield determination in activation analysis can be used as isotopic radiotracers by labelling of the carrier solution or as non-isotopic radiotracers for precipitation reactions with a labelled reagent as last separation step or for extraction processes with a labelled organic complexing agent. These possibilities are demonstrated by selected examples concerning determinations by neutron and also by photon activation (W, Cu, F, I, Sn). Suitable tracer nuclides (isotopic or non-isotopic) and ways to increase their number are given. Advantages and disadvantages of the different radiotracer methods for yield determination are discussed.
