MULTIPLE ADDRESSEES THIRTEEN THE STRO!JTIUN-90 PROCEDURE IS DESIGNED SO THAT EACH SAMPLE RUN CA!I BE REA!IALYZED AFTER 14-DAY I;iGRO!IJTH OF Y-90 BECAUSE THE SEPARATED SR-90 PORTION OF THE SAMPLE IS STORED FOR REANALYSIS. IV. QUALITY CONTROL A. INTERNAL QUALITY CONTROL - IilTERNAL