Allow to cool, then centrifuge for 5 minutes. 13. Decant, pouring the supernatant liquid into a 4O ml centrifuge tube. 14, Add 1 ml barium carrier solution and 0.5 ml of Na,CrO,. Repeat steps 1i and if. 15. Decant the supernatant liquid into a 2 oz. polyethylene bottle. 16. Add 3 drops of concentrated HCl and 1 ml yttrium carrier solution. lf. Store the solution for two weeks. Second Milk 1. Transfer the equilibrated solution to a 40 ml centrifuge tube. Heat in a water bath regulated at approximately 90°C. Adjust the pH to 8 with NH,OH, stirring continuously. H202 (30%). Add 6 drops of Continue heating to remove Ha0s. Cool to room temperature before centrifuging. the supernatant liquid to a 150 ml beaker. Decant, transferring Record the hour and date. Add 25 mi of distilled water to the precipitate in the centrifuge tube. Dissolve the precipitate by adding 1:3 HCl dropwise with stirring. Heat in a water bath and adjust pH to 8 with NH),OH, stirring continuously. Cool to roon temperature and centrifuge for 5 minutes. Combine the supernatant liquids and save for recovery determinations. Add 25 ml of distilled water to the precipitate. Add 1:35 HCi dropwise until the precipitate just dissolves. Add 20 mg of strontium as holdback carrier. Heat in ea water bath and adjust pH to 8 with NH,OH, stimving continuously e - 29 - ~A say = = . mw * a . 5° ee, Stee mS . “ ae ee cay, . NN 7 te OR, eg EEL MTT 7 genege vee eel? e. “gm? * Free