It has been demonstrated that the interferences on64Cu 511 keV line from nuclides having high energy γ-rays can be effectively reduced physically. An INAA procedure is proposed
and used to determine trace amounts of Cu in biological and environmental samples, However, due to the fact that the interferences
on64Cu 511 keV line are not completely eliminated, the question arises on what is the limit of the non-destructive method for
Cu determination. An equation is derived to establish the relation between the minimum detectable Cu concentration and the
INAA experimental conditions. Based on this equation, an optimised INAA procedure is worked out and applied to blood analysis.
The results show that the optimised INAA procedure is able to determine Cu quantitatively for samples with Na-to-Cu content
ratio less than 600–1000.
This work demonstrates that the64Cu 511 keV line can be used in INAA to determine trace amounts of Cu in biological and environmental materials. The method
to reduce the serious interference in γ-ray spectroscopy from nuclides having high energy γ-rays is discussed. A simple INAA
procedure is proposed and examined for 7 different SRM materials. An accuracy and precision better than 3% are achieved for
tested samples with Na-to-Cu content ratio less than 1000. The minimum detectable Cu concentrations of less than several ppm
are calculated for all the analysed samples. To retain the multi-element capability, the k0-and the modified monostandard methods are applied by using the64Cu 511 keV line as the comparator. With the aid of the program MULTINAA, maximum 32 elements are simultaneously determined
with an accuracy better than 5% for most elements.
Neutron activation analysis based on the199Au indicator for platinum requires the separation of gold at high radiochemical purity. The limit of detection is strongly affected by the presence of gold; with a gold content of 50 pg/g, irradiating for 5 days at 5·1013 n/cm2s is needed to achieve a limit of detection of approximately 30 pg/g. In this case the nuclear interference from gold will exceed the level of platinum by several orders of magnitude and has to be determined with exceedingly high precision. Preliminary results for SRM 1577 Bovine Liver with 95% yield gave consistent results for Au, but Pt could not be detected.
Authors:V. Borghi, L. Lin, S. Silva, E. Haber, and B. Wajchenberg
This work reports the radioiodination of human thyrotropin (hTSH) in our laboratory (IPEN) and evaluates its quality in comparison with a commercial product. The radioiodination yield obtained in 20 experiments ranged from 18.5 to 56.3%, while the purification recovery ranged from 75.5 to 124.0% and the specific activity ranged from 1.01 to 3.10 MBq g–1. The values for the distribution coefficient revealed in the purification of radioiodinated hTSH ranged from 0.232 to 0.371. When tested concomitantly in the same radioimmunoassay system, the IPEN and the commercial tracer presented parallel standard curves. A highly significant correlation ion was observed between the quality control samples estimated through both curves (p<0.001). These results confirm the quality of the hTSH radioiodinated at IPEN and suggest the acquirement of self-sufficiency in this in vitro nuclear technology.
Authors:B. Lin, L. Yang, H. Dai, Q. Hou, and L. Zhang
Soybean oil based polyols (5-OH polyol, 10-OH polyol and 15-OH polyol) were synthetised from epoxidized soybean oil. The melting
peak of polyols and the relationship between melting peak and the number-average functionality of hydroxyl in polyols were
investigated by differential scanning calorimetry (DSC). The thermal decomposition of polyols and some of their thermal properties
by thermogravimetry (TG) and derivative thermogravimetry (DTG) were also studied. The thermal stability of polyols in a nitrogen
atmosphere was very close hence they had a same baseplate of triglyceride for polyols. The extrapolated onset temperature
of polyols in their thermal mass loss, first step had a decreasing order: 5-OH polyol>10-OH polyol>15-OH polyol due to the
difficulty in forming multiple elements ring of them had the same order.
The thermal behavior of polyols under non-isothermal conditions using Friedman’s differential isoconversional method with
different heating rates indicated that the 5-OH polyol had the lowest activation energy in thermal decomposition amongst these
polyols according to the same fractional mass loss because of the weakest intramolecular oligomerization. The 15-OH polyol
was prior to reach the mass loss region because the six-member ring is more stable than the three-member ring from 10-OH polyol
and more easily formed.
In recent years chances of using rhenium-186 and rhenium-188 as radioactive isotopes in diagnostic and therapeutic applications
are increased very much due to the characteristic radiochemical and chemical properties of these two radioisotopes. In particular,
chemical similarities between99Tc and99mTc pair and186Re and188Re pair make it easier to correlate the two groups of compounds. Rhenium-188 is generated from the beta-decay of tungsten-188
which was produced by double neutron capture on enriched tungsten-186 oxide. It is of great interest to examine the impurities
in the eluate by radiochemical neutron activation. For this purpose, the preconcentration of the impurities in samples were
necessary, and it was achieved by adsorption on hydrated magnesium oxide.
In the present study, the characteric-structure relationship of epoxidized soybean oils (ESO) with various degrees of epoxidation
has been investigated. FTIR analysis was used to identify the relative extent of epoxidation of the samples during the epoxidation
reaction. The viscosities of ESO were much higher than that of the raw oil, viscosity increased with degree of epoxidation.
The viscous-flow activation energy of ESO was determined to be higher than that of the raw oil (20.72 to 77.93% higher). Thermogravimetry
analysis (TG) of ESO was used to investigate the thermodynamic behavior of the samples. With increasing degree of epoxidation,
the thermal stability of the samples initially decreased, then increased at the final reacting stage. Differential scanning
calorimeter (DSC) indicated that the melting point of ESO was higher than that of soybean oil. Gel permeation chromatography
(GPC) indicated the molecular mass of the samples increased initially, then decreased, with an increase in the extent of epoxidation.
The use of polypropylene materials in industry for food packaging is increasing. The presence of additives in the polymer matrix enables the modification or improvement of the properties and performance of the polymer, but these additives are potential risk for human health. In this context, an efficient analytical method for the quantitative determination of three antioxidants (2,6-di-tert-butyl-4-methylphenol (BHT), dibutylhydroxyphenylpropionic acid stearyl ester (Irganox 1076), and tns-(2.4-di-tert-butyl)-phosphite (Irgafos 168)) and five ultraviolet stabilizers (2-(2′-hydroxy-5′-methylphenyl) (UV-P), (2′-hydroxy-3′-tert-5′-methylphenyl)-5-chloroben zotriazole (UV-326), 2-(2′-hydroxy-3′,5′-di-tert-butylphenyl)-5-chlorobenzotriazole (UV-327), 2-(2H-benzotriazol- 2-yl)-4-(1,1,3,3-tetramethylbutyl)phenol(UV-329), and 2-hydroxy-4(octyloxy) benzophenone (UV-531)) in polypropylene food packaging and food simulants by high-performance liquid chromatography (HPLC) has been developed. Parameters affecting the efficiency in the process such as extraction and chromatographic condition were studied in order to determine operating conditions. The analytical method showed good linearity, presenting correlation coefficients (R ≥ 0.9977) for all additives. The limits of detection and quantification were between 0.03 and 0.30 μg mL−1 and between 0.10 and 1.00 μg mL−1 for eight analytes, respectively. Average spiked recoveries in blank polypropylene packaging and food simulants were in the range of 80.4–99.5% and 75.2–106.7%, with relative standard deviations in the range of 0.9–9.1% and 0.2–9.8%. Dissolving the polypropylene food packaging with toluene and precipitating by methanol was demonstrated more effective than ultrasonic extract with acetonitrile or dichloromethane for extracting the additives. The method was successfully applied to commercial polypropylene packaging determination, Irgafos 168 and UV-P were frequently found in six commercial polypropylene films, and the content ranged from 166.47 ± 5.11 to 845.27 ± 29.31 μg g−1 and 2.10 ± 0.29 to 19.23 ± 1.26 μg g−1, respectively.
Authors:B. Chen, L.-W. Li, Y.-J. Lin, Z.-H. Wang, and G.-D. Lu
Rice sheath blight, caused by Rhizoctonia solani, is the most serious disease in the southern rice producing regions of China. The use of resistant varieties is the most economic strategy to control the disease. In this paper, a seedling inoculation method was used to evaluate rice germplasm resources for resistance to sheath blight. A total of 363 rice varieties were evaluated with a set of R. solani isolates. The results indicated that the rice varieties generally lacked resistance to R. solani, and no highly resistant/immune (HR) variety was found. However, two varieties displayed clear resistance (R) and 37 showed moderate resistance (MR) to the fungus. Overall, hybrid rice varieties have better resistance than conventional rice varieties, and among hybrid rice varieties, those with the II-32A sterile line genetic background were the most resistant. The results also indicated significant interactions between rice varieties and pathogen isolates, suggesting that an understanding of local R. solani populations is needed when recommending varieties to local growers.