No abstract available

No abstract available

[en] The procedures of labelling different types of haptenes with radioactive iodine are described. Consideration is given to the choice of suitable antisera and ¹²⁵I-radioligands in various homologous and heterologous combinations for radioimmunoassay. In addition to binding radioligand-antiserum interactions, factors are discussed that influence antibody specificity. (author)

[en] Instrumental and radiochemical neutron activation analysis have been applied to a comprehensive trace characterization of aluminium oxide and aluminium nitride powders using conventional irradiation conditions as well as a special facility providing an extremely low ratio of fast to thermal neutrons enabling to reduce essentially the production of ²⁴Na via the reaction ²⁷Al(n, α). Irradiation modes and experimental parameters are given for the determination of 56 elements leading to limits of detection below 100 ng g^-1 for 39 elements. For the analysis of sample materials of good and high purity using usual neutron flux profiles, the selective removal of ²⁴Na was achieved by its adsorption on a hydrated antimony pentoxide (HAP) column from 12 M HCl. For a number of elements, the results obtained on materials of different purity grades are compared with those obtained by inductively coupled plasma atomic emission spectrometry within an interlaboratory intercomparison

[en] An optimized instrumental neutron activation analysis method was applied to the comprehensive trace characterization of good- and high- purity silicon nitride powders of different origins. Experimental modes are given for 55 elements leading to limits of detection below 1 ng g^-1 for 28 elements, between 1 and 100 ng g^-1 for 19 elements and higher than 100 ng g^-1 for 8 elements. For the removal of the radionuclides ¹⁴⁰La, ¹⁸²Ta and ¹⁸⁷W, which cause the major activity in certain types of materials, radiochemical procedures based in cation exchange from 2 M HCl and anion exchange from 2 M HF were developed. ⁶⁴Cu was selectively extracted with dithizone from 10 M HF for counting the 511-keV line. By radiochemical neutron activation analysis, the limits of detection were improved by up to three orders of magnitude. Comparison with results obtained by inductively coupled plasma (ICP) atomic emission spectrometry and ICP mass spectrometry shows satisfactory agreement and demonstrates the advantages of neutron activation analysis especially when low elements contents are to be determined. (author). 30 refs.; 2 figs.; 6 tabs

[en] The high activity of the radionuclides ⁶⁵Ni (t_1/2=2.52 h) and ⁵⁸Co (t_1/2=70.8 d) imposes severe limitations on the performance of direct instrumental neutron activation analysis of nickel. The extent of the interference of the ⁵⁸Co depends on the ratio of the fluxes of the fast and thermal neutrons. A method of selective removal of cobalt, based on extraction with β-nitroso-α-naphthol has been developed for the purpose of radiochemical NAA. Separation yields have been determined for 36 elements. The detection limits obtainable with both the instrumental and the radiochemical method are <10^-4 μg/g for the elements Au, Eu, Ir, La, Sc and Sm, between 10^-4 and 10^-3 μg/g for Cr, Cs, Hf, Hg, Lu, Re, Sb, Ta, Th, Tm and Yb, between 10^-3 and 10^-2 μg/g for As, Ag, Br, Ce, Ga, Na, Ru, Se, W and Zn, and in the range 0.01-1 μg/g for Ba, Cd, Co, Fe, In, K, Mo, Nd, Pd, Rb, Sn, U and Zr. (orig.)

[en] Instrumental neutron activation analysis (INAA) and inductively coupled plasma atomic emission spectrometry (ICP-AES) have been optimized for application to a comprehensive analysis of silicon carbide powders. Via medium- and long-lived indicator radionuclides with half lives between 2.3 h (¹⁶⁵Dy) and 12.4 a (¹⁵²Eu), INAA can detect 55 elements. Analytical parameters and experimental modes are given with limits of detection obtained for a silicon carbide powder of typical purity grade. For the performance of ICP-AES, a wet-chemical decomposition procedure was optimized for sample portions of about 1 g using a mixture of high-purity conc. HF, HNO₃ and H₂SO₄ for digestion in autoclaves with a PTFE-liner. For all investigated elements, recoveries ≥98% were obtained. By scanning wavelength profiles, interference-free emission lines were found for 56 elements. By the combined performance of INAA and ICP-AES, 66 elements were assayed in the analysed silicon carbide powder. The limits of detection were below 0.01 μg/g for 24 elements, they were between 0.01 and 0.1 μg/g for 17 and between 0.1 and 1 μg/g for 15 elements. The remaining 10 elements were detectable at levels >1 μg/g. The comparison of results of these two methods as well as of results obtained by other laboratories shows that, for the most common impurities, a satisfactory degree of accuracy could be achieved. (orig.)

[en] Instrumental and radiochemical neutron activation analysis have been applied to a comprehensive trace characterization of aluminium oxide and aluminium nitride powders using conventional irradiation conditions as well as a special facility providing an extremely low ratio of fast to thermal neutrons enabling to reduce essentially the production of ²⁴Na via the reaction ²⁷Al(n, α). Irradiation modes and experimental parameters are given for the determination of 56 elements leading to limits of detection below 100 ng g^-1 for 39 elements. For the analysis of sample materials of good and high purity using usual neutron flux profiles, the selective removal of ²⁴Na was achieved by its adsorption on a hydrated antimony pentoxide (HAP) column from 12 M HCl. For a number of elements, the results obtained on materials of different purity grades are compared with those obtained by inductively coupled plasma atomic emission spectrometry within an interlaboratory intercomparison

[en] Determination of progesterone in milk is a very useful tool for the detection of insemination failures as early as three weeks after breeding, which makes possible to hasten conception in some animals. When compared with actual pregnancies, the results of progesterone determination can also provide information on the rate of embryonic mortality and, in consequence, a basis for objective evaluation of the results of any control measures in this respect. Moreover, determination of progesterone is of value is studying the oestrous cycle and in differential diagnosis of reproductive disorders. In performing the assay, preference is given to direct determination of progesterone in milk without extraction. Labelling with iodine-125 is useful in processing large batches of samples. (authors)

[en] The biological half-lives of ¹³¹I-labelled homologous IgG of colostral and serum origin were determined in two litters totalling 20 piglets with and without correction for increases in body mass. The half-lives of IgG in the blood were 8 days without the correction, but exceeded 20 days when corrected for body mass. There were practically no differences in the biological half-lives of serum and colostral IgG. (orig.) 891 AJ/orig. 892 MKO