- 5 - The radiochemical technique for the separation of the nuclides by means of ion exchange was adapted from the proce- dure developed by Swartout et al, (1944) and Tompkins et al, (1947). Preparation of samples The dried samples were wet ashed with HNOz and H209, evaporated to dryness and redissolved in 0.2N HCl. To check the radiochemical procedures a "control" sample was prepared in which 0.0Oeu¢ of wi85 was added to a 300-mg portion of dry Puget Sound fisn and then processed in the same manner as the test samples. The samples were filtered and the filtrates were passed through cation resin columns prepared in the following manner. Preparation of the resin column Dowex 50*, a sulfonated polystyrene resin of the cationic type, of mesh size 100 - 200, was washed three times with 6N HCl, rinsed three times with distilled water and twice with dilute HCl. The resin suspension was placed in a glass column 6 mm in diameter and 100 mm in length containing a glass wool plug in a constriction at the base of the tube. Three column volumes of 0.2N HCl were run through the resin until the eluate was clear and the desitred flow rate was obtained. * Available from Dow Chemical Co., Midland, Michigan |