It was found that some trivalent cations form precipitates with humic acid at pH 4.2. The precipitates contain less metal
cations than suggested by the neutralization-charge model for soluble complexes based on the available anionic sites. It is
suggested that cations, which can form inner-sphere complexes, may precipitate before they are completely neutralized, while
those that do not form complexes precipitate only after complete neutralization.
The preparation of high specific activity128I by neutron activation of KIO3 is described. The128I– produced in a Szilard-Chalmers process is eluted with a water-isopropylamine mixture which dissolves only KI but not KIO3.
It is suggested that Am3+ is forming different complexes with humic acids. At pH 4–5 at low concentration of Am3+ the complex is water soluble, while at higher concentration of Am3+ an insoluble complex is formed.
The use of5 5Co for positron emission tomography (PET) is criticized on the grounds that its 477 keV -rays would interfere with the positron annihilation measurements. This interference will lead to distorded pictures, lower resolution and lower tumor-non tumor ratios for5 5Co-bleomycin. It is suggested that5 7Co-bleomycin used in single photon imaging is better replaced by5 7Ni-bleomycin rather than by5 5Co-bleomycin for PET studies.
A method for the absolute calibrations of -rays spectrometers for voluminous samples using natural radionuclides is suggested. The method is based on relative calibration with a solution of 232Th salts and absolute calibration with K2CO3 or KCl.