Sparation Of Some Relevant Cyclotron Produced Redioisotopes :

Wael Refaat Abdelgelel

Since the short-lived cyclotron produced radioisotopes are findingincreasing applications in medicine, industry, research studies and otherfields of life sciences, especially gallium-67, indium-Ill and thallium-201, therefore the main objective of this work is to study the separationand purification of these cyclotron produced radioisotopes as well asrecovery of the encountered highly expensive target materials.This thesis consists of three basic chapters:Chapter(l) Introduction:This chapter includes the routine routes of radionuclide productionby neutron and charged particles activation using both reactor andcyclotron facilities. Structure, cross section and nuclear data importanceare also reported. General chemistry of the products radionuclides andtheir target materials are illustrated. It also implies a concise literaturereview including the nuclear medicine application, production,irradiation, cooling, radiochemical separation and quality assurance testsof the respective product radionuclides.Chapter (2) Experimental:This chapter includes the various chemicals, reagents, radioactivematerials and instnimentation used in this study. The details of theexperiments carried out in this thesis are also reported implying themethod of preparation of the used inorganic ion exchanger resin; 12-molybdocerate (IV). Description of the distribution behaviourinvestigations using static and dynamic studies and the factors affectingthem; including, nature and chemical composition of the exchangemedium and the amount of the radiotracer are illustrated. Thechromatographic column separation studies and the factors affectingthem; including, types, concentration and flow rate of the eluent aredescribed confidentially.Chapter (3) Result and discussionIncludes the obtained results as well as their analysis anddiscussion. Detailed and systematic studies including the distributionbehaviour; breakthrough characteristics and elution profiles for the targetand the product radionuclide couples have been carried out. Thedistribution behaviour of the individual metal ions is determined as ameasure of the corresponding batch distribution coefficient (K.J) values asa function of nature and composition of the equilibrating media (HCI andRN03) as well as the concentration of the radiotracer on the sorbentmaterial dried at 50°C in shaker thermostat adjusted at 25±loC usingbatch equilibrium method. The obtained distribution behaviourrelationships (N values in ml/g vs. concentration of the equilibratingmedium) are discussed on the base of the target and product chemicalspecies which are expected to predominate in the equilibrating solutionand their interactions with the molybdocerate(IV) matrix. Theexperimental conditions necessary for high target/product separationfactors (a. =I<.J (productJi’K«targetj) are elucidated for each couple. It showsthat the distribution coefficient (N) values of different cations underinvestigation from nitric acid are higher than from hydrochloric acidsolution. Also, the values are high at low acid concentration and decreasewith the increase in acid concentration. As well, the distributioncoefficient (N) values decrease with increasing concentration of theradiotracer. The corresponding uptake values for the individual metal ionsare obtained by the column breakthrough studies. It shows that fastbreakthrough of cations under investigations is observed the higher theconcentration of the radiotracers. Also, fast breakthrough was attainedwith acid concentration increasing where metal ions in hydrochloric acidmove along the column bed faster than in nitric acid solution.Breakthrough characteristics for each target and product radionuclide indifferent acid media have been included. The separation performance ofeach target/product couple has been investigated using smallchromatographic columns of l g l2-molybdocerate(IV) matrix by bothelution and frontal separation methods. The elution performance,radioactivity concentration and elution yield of the product radionuclidefrom 12-m9Iybdocerate(IV) column matrix are implemented byinvestigations under comparable conditions for nature, chemicalcomposition and flow rate of the eluent effects. In elutionchromatography, it is observed that the position of maximum elutionpeaks was displaced to higher eluate volumes with increasing the flowrate of the eluent and with nitric acid than that with hydrochloric acidsolution. Quality control studies, including radiometric determinationsand chemical analysis, proved that the obtained eluates are radionuclidic,radiochemical and chemically pure and satisfy the considered limits foruse of such radionuclides in nuclear medicine. from the obtained resultsand its discussion we can indicate that the optimum operating conditionsfor separation of carrier-free gallium(III) from bulk amount ofzinc(II)can be achieved by using small chromatographic columns ( 0.6 em i.d x3.5 em) filled with l g 12-molybdocerate(IV) gel and passing 500 mixturesolution consists of 5xlO””M zinc(Il) and lO-sM gallium(ill) in 0.05MlIN03_ Elution and purification of the bed matrix from retained Zn(II) iscarried out successively with passing 3ml 0.05M HN03 acid and 1000.05M Hel acid solutions. Thereafter, gallium(III) is eluted and purified110with 7ml O.5M HCI acid solution at a flow rate of 1 mllmin. The elutionyield of gaIIium(III) was found to be about 94.7% of the totalradioactivity present on the column. Separation of carrier-free indium(ill)from bulk amount of cadmium(U) can be achieved by loading Smlmixture solution consists of 5xl0-4MCd(ll) and lO”~ In(1ll) in O.OIMHN03 onto Ig 12-molybdocerate(IV). Elution and purification of the bedmatrix from retained Cd(II) is carried out successively with passing 5mlO.OIM HN03 acid and 2ml O.05MHCI acid solutions. Thereafter, In(lll)is eluted and purified with 14ml O.IM HCI acid solution at a flow rate ofI mllmin. The elution yield of indium(lll) was found to be about 97.3%of the total radioactivity present on the column. Separation of carrier-freeindium(III) from bulk amount of silver(l) can be achieved by loading 5mlmixture solution consists of 5xl0~ Ag(I) and 10-~ In(ll) in O.OIMHN03 onto Ig 12-molybdocerate(IV). Elution and purification of the bedmatrix from retained In(III) is carried out successively with passing 10mlO.IM HN03 acid and 4ml O.2MHN03 acid solutions. Thereafter, Ag(l) iseluted and purified with 25ml 1M HN03 acid solution at a flow rate of 1ml/min. The elution yield of indium(III) was found to be about 98.6% ofthe total radioactivity present on the column. Separation of carrier-freethallium(l) from its lead(II) can be achieved by loading 5ml mixturesolution consists of 5xIO-4MPb(ll) and IO-sMTI(I) in O.OIMHN03 onto19 12-molybdocerate(IV). Elution and purification of the bed matrix fromretained Pb(lI) is carried out successively with passing 7ml O.05MHN03acid and 2ml O.05M HCI acid solutions. Thereafter, TI(I) is eluted with18ml 1M HCI acid solution at a flow rate of I ml/min. The elution yieldof thaIIium(I) was found to be about 92.4% of the total radioactivitypresent on the column.Frontal separation method had been used for separation ofpairs of target.materials and produced radionuclides present in large solute volumes. So.the best condition for frontal separation ofGa(III) from its target Zn(II) isby passing 35ml mixture solution of5xW4M Zn(II) and lQ”sM Ga(III) in0.05M RN03 through a chromatographic column packed with Ig 12-molybdocerate(lV) gel at a flow rate of Im1lmin.Frontal separation ofIn(III) from its target Cd(II) can be achieved by passing 6000 mixturesolution of 5xl04M Cd(Il) and 10’~ In(III) in O.OIMRN03 through achromatographic colunm packed with 19 12-molybdocerate(IV) gel at aflow rate of lmllmin. Frontal separation of In(III) from its target Ag(I)can be achieved by passing 20000 mixture solution of 10””’MAg(I) and10·sM In(III) in O.1MRN03 through a chromatographic column packedwith 19 l2-molybdocerate(IV) gel at a flow rate of lmllmin. Frontalseparation of Tl(l) from its target Pb(II) can be achieved by passing200ml mixture solution of 5xl04M Pb(II) and 10·sM Tl(I) in 0.05MRN03 through a chromatographic column packed with Ig 12-molybdocerate(IV) gel at a flow rate of lml/min.