8. Add 30 mil of 20% HDEHPto the first separatory funnel. Shake for two minutes and allow the phases to separate. Record the date and time of this last separation as T; on data sheet. 9. Drain the aqueous phase into a bottle containing a known amount of yttrium 10. 11. C. carrier (10 - 20 mg). Discard the organic layer. Count the sample for 85gr with the gamma spectrometer. Compute the 85sr recovery by taking the ratio of the number of net counts in the sample to the number of net counts in the standard. The standard is prepared by adding the same amount of 85$r as was added to the sample to a bottle containing yttrium carrier and 30 mi of 0.08M HCl. Store the sample for two weeks, Tg Separation (Second Milking) 1. Transfer the sample to a 125 ml separatory funnel. Rinse the bottle with two 15 ml portions of 5% HDEHP (v/v in toluene) and add each rinse to the separatory funnel. Shake for two minutes and allow phases to separate. Record the date and time of separation as Tg on data sheet. 2. Drain off aqueous layer into original bottle and record Tg time as T, on this bottle. This portion will be saved in case a rerun or verification is necessary. 3. Add 30 ml of 3N HNOs: to the 5% HDEHPin the separatory funnel and shake for two minutes, Allow phases to separate and drain aqueous phase into a 40 ml conical centrifuge tube. 4, Adjust to pH 9 with cone NH4OH, centrifuge for 10 minutes at 1800 rpm and diseard the supernatant. Dissolve the precipitate in 20 ml of 3N HNOg and repeat the NH4OH precipitation twice. Dissolve the final precipitate in 2 - 4 ml of 1M HCL 5. Add 25 - 30 ml of deionized water and place in a water bath at 90°C for 15 minutes. Add 3 - 4 ml of saturated (NH4)9C.04 and digest in a water bath for 10 minutes. Filter the sample with a millipore filter apparatus collecting the precipitate on a dried, tarred glass fiber filter paper. Wash sample once with deionized water followed by an alcohol wash. Do not draw excess air through thefilter. Carefully remove the filtered sample and dry in oven for one hour at 100°C, Remove from oven and allow to cool in a dessicator for 20 minutes. Weigh sample and record weight. Calculate yttrium yield from the net weight of the precipitate. Count the sample in the low background beta counter and compute the 90sr activity present in the sample from the measured 90y activity. A-23-2