CHLORINE 235 



Chlorine 36 (~4.4 X 10'' yi) Beto 0.713 Gamma 



Cat. No. Sp. .id. For til Cost Chem. Cont. Radiochem. Cont. 



C1-36-I O.OMc/g KCl .133/6^0 — 145 mc K« (12.44 hr) 



100 mc S's (87.1 days) 

 0.01 mc P32 (14.3 days) 



C1-36-P 10-20 Mc/g HCl $5/mC — — 



MicaW. Int. C. Scint. C. 50% Self-abs. 



1.7 X 10-^ 1.8 X 10-^ 8.3 X 10-2 91 (calc.) 



Critical Org. Body Air Water Effect. Ti,^ 



Total body 200 ^c 4X10"' 2 X 10-^ 2<) days 



Intake Levels. Animal intakes vary widely and usually exceed the 

 needs. About 5 mg/day is adecjuate for rats. A recommended nutrient 

 solution for plants contains 0.177 ppm. Crop plants contain about 0.2 

 to 2 per cent. Human beings and dogs have been reported to have about 

 1 g chlorine per kilogram body weight. Serum contains about 6 mg/ml 

 of chloride expressed as sodium chloride. 



Radioassay. Preparation C1-36-P is probably the best to use, since 

 most if not all of the radiocontaminants have been removed. The K"*^ 

 and P^- contamination is eliminated by decay. However, time will not 

 permit removal of S^^ in this way. If there is any possibility of S^* being 

 present, the samples should be counted with an absorber of about 

 10 mg/cm- to eliminate the S*^ contribution. Solution counting is sat- 

 isfactory, although the higher sensitivity of internal or end-window 

 counter measurements employing solid samples may be required. Atten- 

 tion is called to CP*, which may be used by workers near cyclotron pro- 

 duction. CP^ has a half-life of 38 min, which restricts its use, but it emits 

 very energetic beta particles and gamma rays, so that the radioassay can 

 be made simple and rapid. 



Chemistry. Tissues can be ashed by treating up to a 5-g sample with 

 20 ml of a 5 per cent NazCOs solution in a Pt dish, evaporating to dryness, 

 and igniting at dull-red heat. The ash is extracted with hot H2O, filtered, 

 and washed, and the residue is reignited and extracted with acid. This 

 solution is added to the first H2O extract. Simple methods that do not 

 require ashing have been described for determination of chlorides in serum 

 and spinal fluid (Cl-1, Cl-2). This allows determination of turnover 

 by convenient procedures, since both the chemical and radioactivity 

 measurements can be made directly on these samples. 



Typical Methods. In a study with dogs (Cl-3), about 5 fxc CP*^ in 

 18 mg NaCl per 10 lb body weight was injected into the hind-leg vein. 

 Aliquots of urine, blood serum, and Formalin suspensions of feces were 

 dried on filter-paper disks, mounted on a metal backing, and counted with 

 an end-window tube through an absorber of 10.335 mg/cm-. In a similar 



