Patent Number: 051456362
Section: description

EXAMPLES Example 1 Preparation of Aluminum Perrhenate Soluble Irradiation Target Procedure No. 1 0.1 ml concentrated nitric acid was carefully pipetted into a beaker containing 50 mg rhenium metal. After two to three minutes, 0.1 ml 1:1 v/v concentrated nitric acid:water solution was added to the reaction mixture, and the mixture was allowed to react at room temperature for 20 minutes. 0.5 ml water was added to the mixture, followed by the addition of 0.2 ml of a 0.447M aluminum chloride solution. The mixture was heated to dryness at 95.degree. C. for 12 hours. 1 ml water was added to the beaker to dissolve the residue solid, then the solution was filtered. The filtrate was heated to dryness at 95.degree. C. for 12 hours to yield a white solid, aluminum perrhenate. The elemental analysis of Al and Re is shown in Table I. Procedure No. 2 To 50 mg rhenium metal was carefully added 0.5 ml 30% H.sub.2 O.sub.2 solution. After 10 minutes, 0.5 ml water was added to the mixture and the mixture was heated for 30 minutes at 95.degree. C. 0.2 ml of 0.447M aluminum chloride solution was added to the mixture, and the mixture was heated to dryness at 95.degree. C. for 12 hours. 1 ml water was added to dissolve the solid, then the solution was filtered. The filtrate was heated to dryness at 95.degree. C. for 12 hours to obtain a white solid, aluminum perrhenate. Procedure No. 3 To 50 mg rhenium metal was carefully pipetted 0.1 ml concentrated nitric acid. After two to three minutes, 0.1 ml 1:1 v/v concentrated nitric acid:water solution was added to the reaction mixture, and the mixture was allowed to react at room temperature for 20 minutes. 0.1 ml ammonium hydroxide (conc.) was added to the reaction mixture, followed by the addition of 0.5 ml water. The mixture was heated at 95.degree. C. until all solids had dissolved, and then 0.2 ml of 0.447M aluminum chloride solution was added to the mixture. The solution was heated to dryness at 95.degree. C. for 12 hours. 1 ml water was then added to dissolve the solid, and the solution was filtered. Finally, the filtrate was heated to dryness at 95.degree. C. for 12 hours to yield a white solid, aluminum perrhenate. Procedure No. 4 The procedure of Procedure No. 1 was followed, except 50 mg enriched Re-185 rhenium metal (95% Re-185, Isotec, Inc., Dayton, Ohio) was used in place of the natural occurrence rhenium metal of Procedure 1. Procedure No. 5 The procedure of Procedure No. 2 was followed, except 75 mg enriched Re-185 rhenium metal (95% Re-185, Isotec, Inc., Dayton Ohio) and 0.3 ml 0.477M aluminum chloride solution was used in place of the natural occurrence rhenium metal and aluminum chloride solution of Procedure 2. Procedure No. 6 The procedure of Procedure No. 3 was followed, except 50 mg enriched Re-185 rhenium metal (95% Re-185, Isotec, Inc., Dayton, Ohio) was used in place of the natural occurrence rhenium metal of Procedure 3. The products of Procedure Nos. 1-6 were dissolved in 2 ml of water, diluted 1:200 in water, analyzed for rhenium and aluminum content and found to contain the amounts of rhenium and aluminum shown in the following Table 1 as .mu.g per ml of sample. TABLE I ______________________________________ Elemental Content (.mu.g/ml) Procedure Number #1 #2 #3 #4 #5 #6 ______________________________________ Al 5.0 5.2 5.4 5.1 7.6 4.5 Re-total 125.8 116.7 131.4 104.6 157.4 103.6 Re-185 46.1 42.6 48.1 97.7 148.4 97.5 Re-187 79.7 74.1 83.2 7.2 9.0 6.1 Re-Al ratio 25.2 22.4 24.3 20.5 20.7 23.0 ______________________________________ EXAMPLE II Irradiation of Soluble Aluminum Perrhenate Targets 0.24 mg samples of aluminum perrhenate produced by Procedures 4, 5 and 6 of Example 1 were placed in quartz irradiation vials, which were sealed by flame under vacuum. The vials were irradiated in a flux of 3.times.10.sup.14 neutrons/cm.sup.2 /sec at the University of Missouri Research Reactor (Columbia, Mo.) for a period of 12-14 days. The vials were then opened and the irradiated aluminum perrhenate was dissolved in 0.5 ml of water. The average activity recovery was found to be greater than 90%, and the activity was identified as .sup.186 Re (by germanium-lithium analyzer) in the form of .sup.186 ReO.sub.4.sup.- (by reverse phase HPLC). EXAMPLE III Preparation of Sodium Tungstate Target 0.5 ml of a 5N NaOH solution was added to 0.2 g of .sup.186 WO.sub.3 (96% .sup.186 W, Oak Ridge National Laboratory, Oak Ridge, Tenn.) in a 5 ml beaker, and the mixture was heated to dissolve the .sup.186 WO.sub.3 material. After dissolution was complete, the mixture cooled to room temperature and adjusted to pH 9 by the addition of 5N HCL and 1N HCl. The solution was heated to dryness to obtain 0.292 g of a white solid, comprising sodium tungstate. EXAMPLE IV Irradiation of Soluble Sodium Tungstate Target A 20 mg sample of sodium tungstate (W-186) prepared by the procedure of Example III was placed in a quartz irradiated vial, which was sealed by flame under vacuum. The vial was irradiated in a flux of 3.times.10.sup.14 neutrons/cm.sup.2 /sec at the University of Missouri Research Reactor (Columbia, Mo.), for a period of seven days. .sup.187 W and .sup.24 Na were allowed to decay from the irradiated material. The vial was then opened and the irradiated sodium tungstate was dissolved in 1 ml of water. The solution was then filtered through a 0.2 .mu.m filter. The activity recovery was determined to be greater than 95%. EXAMPLE V Preparation of Zirconium Tungstate Generator 40 mg of irradiated sodium tungstate prepared as described in Example IV was dissolved in 2 ml of water and filtered through a 0.2 .mu.m filter. To the filtered solution 200 mg of natural occurrence Na.sub.2 WO.sub.4 in 4 ml H.sub.2 O was added to aid in precipitation of insoluble tungstate. The tungstate solution was then added drop by drop to an acidic zirconyl solution containing 312 mg ZrO(NO.sub.3).sub.2 in 6 ml of HCl solution, pH 1. The pH of the resulting zirconium tungstate mixture was 6.0. The mixture was then filtered and washed with 50 ml of water. The gel-precipitation yield (percentage of .sup.188 W initially present which is complexed in the gel) was greater than 95%. The filtered gel was air dried overnight, packed into a conventional generator column, and eluted with physiological saline. The zirconyl tungstate generator was determined to have an elution yield of 66%. While the invention has been described in connection with various presently particularly preferred embodiments, various modifications will be apparent to those skilled in the art. Any such modifications are intended to be within the scope of the appended claims, except insofar as precluded by the prior art.