Cd-hem method is the most simple and easy method for the determination of metallothionein (Mt) . In this method, Mt-unbound Cd is removed by a treatment with rat hemoglobin (Hb) and heating at 100 °C. This step is usually repeated 3 times. The authors have carried out several experiments on the Cd-removal process in the Cd-hem method. Bovine and swine Hbs have a high affinity for Cd and are satisfactorily available for the Cd-hem method instead of the rat Hb. Although Mt is not lost by the treatment with Hb and heating at 100°C, only a single treatment is recommended because it is enough for the removal of Mt-unbound Cd. For the accurate determination of Mt, the value of blank which is determined without biological samples should be subtracted from that of biological samples because the Mt-unbound Cd cannot be removed completely by this treatment even though the treatment is repeated 3 times.
Tritiated water vapor from a radioluminous watch was transferred to water in a small vessel situated near the watch through HTO exchange in a short time. From the mathematical transfer model, the concentration of HTO vapor was found to amount to be about 108 Bq/g, which was about 1011 times greater than the environmental background level of tritium in water. The large difference in the specific activity of HTO between the vapor in the air and the water in the vessel caused the prompt increase of HTO concentration in the water.