A method preparing solutions of a mixed chloro, bromo-complex of tellurium labeled with123mTe is described. The solutions are shown to be excellent standards for calibrating radioisotope dose calibrators used to measure123I.
Multielement determinations of coal fly ashes (NIST SRM-1633a and BCR CRM-38) have been carried out by instrumental photon activation analysis using 30 MeV bremsstrahlung and the internal standard method coupled with the standard addition method. In these determinations, some major and minor constituent elements in the samples were properly used as effective internal standards. As a result, it was demonstrated that concentrations of 18 elements were determined accurately and precisely. Furthermore, a similar multielement determination has also been examined using 20 MeV bremsstrahlung. In this case, it was proved that better results can be achieved, because all interfering reactions were eliminated completely.
Multielement determinations in the certified reference materials of soils (IAEA soil-5 and 7) have been studied fundamentally by instrumental photon activation analysis using the internal standard method coupled with the standard addition method. For the soil-5 sample, in the first place, the qualities of the comparative standards prepared by two processing methods were compared with each other. As a result, it was demonstrated that a highly accurate and precise multielement determination can be achieved easily by minor improvement in the processing method of the comparative standard to ensure homogeneity. The utility of this processing method for soil samples was proved further through a similar analysis in another soil sample (IAEA soil-7).
The Standard Reference Material 4351 from the National Institute of Standards and Technology is acknowledged to be inhomogeneous. The value of a single analysis for239Pu+240Pu could lie within a wide range, but the accuracy of the analysis can be corroborated by comparing the corresponding238Pu/239Pu+240Pu or240Pu/239Pu values with the relationships between these ratios and the total plutonium concentration.
of the liquid 2-methylfuran, 5-methyl-2-acetylfuran and 5-methyl-2-furaldehyde were derived from the standard molar energies
of combustion, in oxygen, at T = 298.15 K, measured by static bomb combustion calorimetry. The Calvet high temperature vacuum sublimation technique was
used to measure the enthalpies of vaporization of the three compounds. The standard (po = 0.1 MPa) molar enthalpies of formation of the compounds, in the gaseous phase, at T = 298.15 K have been derived from the corresponding standard molar enthalpies of formation in the liquid phase and the standard
molar enthalpies of vaporization. The results obtained were −(76.4 ± 1.2), −(253.9 ± 1.9), and −(196.8 ± 1.8) kJ mol−1, for 2-methylfuran, 5-methyl-2-acetylfuran, and 5-methyl-2-furaldehyde, respectively.
57Co was produced with high pure nature iron irradiated by 8.5MeV deuterons. TBP-benzene extraction method and anion-exchange method were used to separate and purify it. The purified57Co was prepared into standard solution of about 30 to 50 g Co2+/ml carrier concentration and about 0.1 mol/l HCl. The specific activity of the standard solution was measured with 4
(ppc)- coincidence counting method. The final result was 476.82(1±0.42%)Bq/mg.
The preparation of a set of standards for the calibration of the analysis of deuterium using the2H/3He, p/4He reaction is described. Important considerations in the selection of a suitable standard are that it should be stable under irradiation and be simple to prepare with ready control of the amount of analyte. These requirements were met by Ca/OH/2 which was prepared by the replacement of hydrogen with its isotope in known proportions in the reaction of CaO with water.
The National Institute of Standards and Technology (NIST) Rocky Flats Soil-II Standard reference material (SRM) is being certified
through a statistical analysis of results from an interlaboratory comparison of fourteen laboratories from four countries.
Mean values were calculated as the most robust and reliable certified values for each of the radionuclides. Twenty two radionuclides
and four isotopes ratios were evaluated based on reported data. This article describes the approach for establishing the certified
values and uncertainties for the radionuclides in the Rocky Flats Soil II SRM.
The need for standardisation in bibliometric research and technology is discussed in the context of failing communication within the scientific community, the unsatisfactory impact of bibliometric research outside the community and the observed incompatibility of bibliometric indicators produced by different institutes. The development of bibliometric standards is necessary to improve the reliability of bibliometric results, to guarantee the validity of bibliometric methods and to make bibliometric data compatible. Both conceptual and technical questions are raised. Consequences of lacking standards are illustrated by typical examples. Finally, particular topics of standardisation are proposed based on experiences made at ISSRU.
A derivative form of NAA is proposed which is based on the use of an endogenous internal standard of already known concentration in the sample. If a comparator with a known ratio of the determinand and endogenous standard are co-irradiated with the sample, the determinand concentration is derived in terms of the endogenous standard concentration and the activity ratios of the two induced nuclides in the sample and comparator. As well as eliminating the sample mass and greatly reducing errors caused by pulse pile-up and geometrical differences, it was shown that in the radiochemical mode, if the endogenous standard is chosen so that the induced activity is radioisotopic with that from the determinand, the radiochemical yield is also eliminated and the risk of non-achievement of isotopic exchange greatly reduced. The method is demonstrated with good results on reference materials for the determination of I, Mn and Ni. The advantages and disadvantages of this approach are discussed. It is suggested that it may be of application in quality control and in extending the range of certified elements in reference materials.