288 RHENIUM 



Rhenium 186 (3.87 days) Beta 0.64, 0.95, 1.09 Gamma 0.132-1.7 



Cat. No. Sp. Act. Form Cost Chem. Cont. Kadiochem. Cont. 



Re-186-I 1.23mr/mp; ATetal $12/65 mc — 150 mc Re^^Mie.g hr) 



R//7nc 

 0.2 



Critical Org. 

 Thyroid, skin 



Intake Levels. Rhenium is a rare element, and little is known of 

 naturally occurring levels in biological material. In rats, 900 to 1000 

 mg/kg of rhenium as NaRe204 administered intraperitoneally is fatal. 



Radioassay. Routine beta- or gamma-counting methods can be used. 

 If desired, the Re^*^ can be allowed to decay out. However, this is 

 usually not necessary, since standards can be measured along with the 

 samples to give the decay corrections for the particular preparation. 

 However, if both isotopes are measured, it must be remembered that the 

 self-absorption characteristics will change with time. 



Chemistry. Tissues can be dry-ashed; wet-ashing may cause losses 

 under certain conditions. Chemical methods have been described for 

 rhenium, but these are applicable only for samples with relatively high 

 concentrations, and procedures have yet to be developed for biological 

 materials. 



Typical Methods. A study has been described on the thyroid accumu- 

 lation of this element (Re-1). The rhenium metal irradiation unit was 

 dissolved in 2 ml concentrated HNO3 and diluted for dosage to the animal. 

 The Re^*^ was allowed to decay out before the time of experiment. Rats 

 were injected intraperitoneally with about 300,000 counts/min of activity 

 in 3 to 100 Atg Re in 1 ml solution. One- to two-gram samples of blood, 

 lung, liver, and muscle and the entire thyroid were placed in 15-mm metal 

 planchets, moistened with 1 per cent NaOH, and dried at 105°C and then 

 at 120 to 130°C. The samples were ashed at 450 to 500°C for 18 hr, the 

 ash coated with about 1 ml of 1 per cent celloidin, and the activity counted 

 with a thin-mica-window tube. No self-absorption corrections were 

 necessary. 



Re-1. Baumann, Emil, N. Zizmer, Eleanor Oshry, and S. M. Seidlin: Behavior of 

 Thyroid toward Elements of the Seventh Periodic Group. II. Rhenium, Proc. 

 Soc. Exptl. Biol. Med., 72: 502-506 (1949). 



