IRON 



261 



Iron 55 (2.94 yr) Beta 



Iron 59 (45.1 days) Beta 0.26, 0.46 



Cat. No. Sp. Act. Form Cost Chein. Cant. 



Fe-5559-I Fe", 0.7 mc/g Metal $38/12 mcFe" — 



Fe", 0.4 mc/g + 6.5 mc Fe" 



Fe-5559-P Fe", 1-4 mc/g FeCU «35/mc — 



Gamma K 

 Gamma 1.3, 1.1 



Radiochem. Cont. 



Intake Levels. Adult man usually consumes about 12 mg iron per day. 

 Livestock roughages provide 50 to 100 mg/lb, which is well above needs, 

 estimated at about 9 mg/lb. Approximately 0.25 mg/day is adequate 

 for rats. The body of man contains 3 to 3.5 g, of which 2.4 to 2.7 g is in 

 the form of hemoglobin. Blood contains about 50 mg/100 ml, and 

 plasma, about 0.5. A recommended nutrient solution for plants contains 

 about 1.2 ppm, and crop plants range from 20 to 5000 ppm on a dry basis. 



Radioassay. The mixture of Fe^^ and Fe^^ may be used in general 

 tracer work, especially if the cost is an important factor. Usually the 

 counting measurements will record only the Fe^^. Preparation Fe-59-P 

 offers the advantage of a shorter half-life, which may be important in 

 human studies, and more easily measured radiation. If beta counting is 

 employed, self-absorption considerations will be important, whereas with 

 gamma counting there will be no problems of sample preparation. Fe^^ 

 and Fe^^ can be used as described in Chap. 5 for double-labeling exper- 

 iments (Fe-1). 



Chemistry. Tissues may be dry-ashed in a muffle furnace up to 550°C 

 or may be wet-ashed with a mixture of nitric and sulfuric acids or with 

 sulfuric and perchloric acids. Iron can be estimated chemically on an 

 aliquot of the ash solution by the o-phenanthroline or a-a-dipyridil 



