A remarkable extraction chromatographic method for the preparation of90Y of high radiochemical purity has been developed. The generator consists of silica gel coated crown ether. It functions as a strong adsorber for90Sr and in the meantime high purity of90Y is eluted with a dilute solution of picric acid after a suitable period. The experiments indicated that DC18C6 coated silica gel is better than that of DB18C6 coated. The extraction capacity of strontium on 3.8% DC18C6 coated silica gel is 5.6 mg Sr/g silica gel. Yttrium is obtained with more than 95% milking yield with radionuclide purity greater than 99.9%. The extraction chromatographic generator does not change its characteristics even after 5 elutions.
A simple solvent extraction method has been developed for the separation of90Y from90Sr. Crown ether dissolved in chloroform was used as a selective reagent and organic picrate anion was chosen as a counter ion. The effect of various factors on the extraction separation of strontium and yttrium in the system have been studied. The extraction equilibrium constant of strontium logKex=9.15 was obtained from the study of the distribution coefficient versus the crown ether concentration. The separation method was simple, resulted high purity (>99.9%) and quantitative yield, and took less than half an hour.
Eleven human hair samples were taken from the Chinese residents of Hong Kong for the study of hair trace elemental level and
environmental exposures. Absolute neutron activation analysis and Ge(Li) gamma-ray spectrometry were applied in the determination
of the trace elemental level. All results are reported in parts per million except for sulfur and oxygen which are reported
in percent. The trace element content of hair from a drug addict was found to be considerably different from other sampled
people. Comparison of the normal concentrations of the trace elements of the Chinese residents of Hong Kong was made with
those from people of various other national, socio-cultural and environmental backgrounds. It was found that together with
a few other trace elements, Ni, Sr, Zr and Hg content of the Chinese Residents of Hong Kong show a higher level than those
of the other sampled people.
Authors:S. Liu, C. Chung, J. Chuang, C. Wang, and N. Aras
Sixteen minor and trace element contents of diet samples from three different social population groups in Taiwan were determined. Samples were prepared using duplicate portion technique by collecting the 15 subjects ate and drank during a 3-day period. Samples were homogenized, freeze-dried, and elemental concentration of minor and trace elements were determined by instrumental neutron activation analysis. Elemental concentrations and daily dietary intake of the elements were compared with those in the other nations, and possible origins were discussed.
Authors:C.-C. Chiang, J.-C. Lee, Y.-M. Chang, C.-F. Chuang, and C.-M. Shu
Knowledge of material safety properties is critical for safe handing in the chemical process industries, especially for flammable
chemicals that might result in serious fires and explosions. This study investigated the flammability characteristics of methanol
under working conditions during the process. The targeted fire and explosion properties, like explosion limits (UEL and LEL),
vapor deflagration index (Kg), maximum explosion pressure (Pmax), and maximum explosion pressure rise [(dP dt−1)max], were deliberately obtained via a 20-L-Apparatus in 101 kPa (i.e., 760 mmHg/1 atm), 150 and 200 °C, along with various experimental
arrangements containing nitrogen (N2) or carbon dioxide (CO2) as inert component. Particularly, this study discussed and elucidated the inert influence on the above safety-related parameters
by two different inerting gases of N2 and CO2. The results indicated that adding an inert component to fuel–inert gas mixtures determined the decrease of explosion range
and flammability hazard degree. The results also demonstrated that CO2 possessed higher inerting capability than N2 in this study.