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Separation of iron-55 from manganese cyclotron target material on a 2% cross-linked anion exchanger in hydrochloric acid
hr. J. Appl. Radiat. Isor. Vol. 36. No. 2. pp. 159-161. 0 Pcrgamon Press Ltd 1985. Printed in Great Britin.
1985
0020-708Xi85 53.00 + 0.00
Separation of Iron-55 from Manganese Cyclotron Target Material on a 2% Cross-linked Anion Exchanger in Hydrochloric Acid f. N. VAN DER
WALT’, F. W. E. STRELOW’ and F. J. HAASBROEK’
‘National Chemical Research Laboratory and ?National Accelerator Centre, P.O. Box 395, Pretoria 0001. Republic of South Africa (Received 25 June 1984) A simple method is presented for the separation of iron-55 from manganese cyclotron targets. Anion exchange chromatography with 9.0M hydrochloric acid on a 20/, crosslinked resin provides separation not only from large amounts of managanese but also from copper and zinc impurities. Separations are sharp and quantitative and less than I pg of manganese remains with the iron-55 when 2 g have been present originally.
Introduction Iron-55 (I,,? = 2.6 y) can be obtained from manganese targets by the 55Mn(d, 2n)“Fe reaction through cyclotron bombardment. It is used medically”-” and in industrial metallurgy.+” Various separation techniques have been described by several authors involving paper chromatography,“’ continuous electronhoresis,‘9’ electrochemical procedures,“““’ extraction(‘2’ aid anion exchange chromatography.“‘.‘4) Danilin et al.“‘) ourified the $jFe isotooe obtained in a reactor from oth& radioactive elements (mainly %Mn and 6oCo) by using Dowex 2-X8 anion exchanger in 8 M hydrochloric acid. Gruverman and Kruger”41 separated cyclotron produced j’Fe from manganese on the anion exchanger Dowex l-X8. JJFe is retained while manganese is eluted from the column with 4N hydrochloric acid. Previously “Fe had been separated from the manganese target material in this laboratory by extraction with diisopropyl ether from 8 M hydrochloric acid. The manganese target used in the Pretoria cyclotron consists of a manganese layer electroplated onto a watercooled copper base. UZn is formed by the reaction “Cu(d 2n)6JZn (t = 244d). To prepare radiochemically pure s;Fe with nzcarrier added, separation from zinc and copper has to be included in the procedure. The separation of iron from copper is not very satisfactory with a 8% cross-linked resin when eluting with 4 M hydrochloric acid because of tailing. From known distribution coefficients”J) it appeaxed that by using a 2% cross-linked resin a considerably improved separation of iron from copper and manganese and a good separation from zinc should become possible. This was investigated in detail and a new procedure for the separation of $‘Fe from manganeK cyclotron targets has been developed and is presented.
Experimental Reagents and apparatus Analytical reagent grade chemicals were used and purified from iron by anion exchange chromatography. “Suprapur” 159
reagent grade hydrochloric acid was used. Water was distilled and further purified by passing it through an Elgastat deionizer. Freshly prepared hydrogen iodide was obtained by passing a solution of potassium iodide through a cation exchanger and eluting hydrogen iodide with water. The resin used was the AGI-X2 polystyrene anion exchanger with quatemary amine exchange groups, supplied by Bio Rad Laboratories, Richmond, California. A borosilicate glass tube (IO mm bore and I50 mm long) which was fitted with a fused-in No. I porosity glass sinter and a tap at the bottom and was joined at the top to a borosilicate glass tube (20 mm bore and I50 mm long) as a reservoir, was used as a column. The column was filled with a slurry of resin until the settled resin reached a mark at 4.4 mL ( I I .Og dry resin) and eauilibrated with IO mL of 9.0 M hydrochloric acid. Be&se the 55Fe activities are difficult- to measure the J9Fe radioisotope and a non-radioactive manganese cyclotron target were used to simulate the etching procedure and the separation of jSFe from the manganese target material. Atomic absorption measurements were carried out on a Varian-Techtron AA-5 instrument. A 4096 channel Multichannel Analyzer, coupled to a Ge(Li) detector was used to identify the s9Fe radioisotope and to measure the activities. An automatic Aimer Central fractionator was used to collect fractions for the preparation of the elution curve. Elution curt-e A solution of I00 mL of 9.0 M hydrochloric acid containing 2.0 g of manganese, I .Og of copper, I .Omg of zinc and l.Omg of iron(III) was prepared. The solution was passed through a resin column containing 4.4mL (= 1.0 g) of AGI-X2 resin of 100-200 mesh particle size, which had been equilibrated with 9.0 .M hydrochloric acid beforehand. The elements were washed onto the resin with small portions of 9.0 M hydrochloric acid, and manganese, copper and zinc were eluted with more 9.0 M hydr&hloric acid (150 mL in total). Iron(II1) was then eluted with 50 mL of 0.1 M hydrbchloric aiid. The flow-rate was 4.0 f 0.3 mL/min and IOmL fractions were collected from the beginning of the sorption step. Those fractions containing 9.0 M hydrochloric acid were evaporated to dryness on a waterbath and the salts were dissolved in IO mL of 0.5 M hydrochloric acid. T’he amounts of manganese, copper, zinc and iron were determined by atomic absorption spectrometry, using the air-acetylene flame and the 219.5,324.8,213.3 and 248.3 mn lines for manganese, copper, zinc and iron respectively. The experimental curve is presented in Fig. I. Separation of iron-59 from manganese target material A non-radioactive manganese target was etched in an etching cell with 10 ml portions of 5.0 M hydrochloric acid containing 0.3% hydrogen peroxide. Finally, the cell was rinsed with water. The acid and wash water were evaporated to cu. 20mL. An accurately measured amount of ve activity was added to this solution. The resulting solution was filtered through a No. 2 porosity glass sinter funnel and the beaker and funnel were washed with 0.5 M hydrochloric acid. The filtrate was evaporated to ca. IOmL volume, cooled, and mixed with IlOmL of concentrated hydrochloric acid (“Suprapur”). The solution was passed through an equilibrated AGI-X2 resin column (as described above). The elements were washed onto the resin with small portions of 9.0 M hydrochloric acid. “Fe was retained on the resin and the other elements were completely eluted with 9.0 M hydrochloric acid, using 100 mL in total. Finally, j9Fe was eluted with 30 mL 0. I M hydrochloric acid. The eluates were evaporated to ca. 2 mL and transferred to IOmL containers with the aid of small portions of 0.1 M hydrochloric acid. j9Fe activities were measured on the funnels,
160
Technical Note
i \ a
(2”6;
E * o.s-
i
CU 11gl
Fe(E) $lYg, ‘x /
h5
\
, “\
XIX
0
‘I
X
100
200 Eluote
300 (mL
Fig. I. Elution curve Mn-Cu-Zn-Fe(II1). 4.4mL (I 1.0 g) AGI-X2 (Cl-form. length 55 mm, I#IIO mm. Flow-rate 4.0 k 0.3 mlimin.
glassware, resin column, and in the eluates and in the “Fe eluate. The results are presented in Table 1. Determination of impurities in the “s9Fe fraction”
Two similar experiments as described above were conducted, but without the “Fe radioisotope. In one case the target was heated in a vacuum pistol at ca. 250°C for 2 h in order to simulate the conditions for the target in the cyclotron. The amounts of manganese, copper and iron were determined in the “Fe fraction by atomic absorption spectrometry using the conditions described above. The results are presented in Table 2. Results and Discussion In the described procedure analytical reagent grade chemicals were used for the preparation of the cyclotron target. Iron, lead, zinc, nickel and other impurities were all less than 10 ppm. Manganese was further purified by electroplating it on a copper base when preparing the cyclotron target. In actual cyclotron bombardments, preparing up to 400 mCi of “Fe per bombardment, no other radionuclides were detected with a multichannel analyzer (probably because of
Table 1. Results of JPFe separated
Fraction qe
used for separation element” &ate elutcd with 9.0 M HCI Iron-59 eluate eked with 0.1 M HCI Resin column Funnel t-&Is.%-ware
400
1 100-200 mesh). Column
the very small quantities of impurities present in the manganese target). Furthermore, according to the distribution coefficients for copper (K,, = 3.4) and manganese (K,, = 4.5),“” residual traces of these elements should easily be eluted from the AGI-X2 resin column with 9.0 M hydrochloric acid. The elution curve experiment (Fig. I) confirmed this. Zinc was completely eluted from the resin column although it has a relatively large distribution coefficient (& = 39.9).“” A distribution coel&ient value of ca. 40 had also been obtained for zinc on the anion exchanger AGI-XI in 12 M hydrochloric acid, but zinc could not be eluted completely from this resin because of serious tailing. With AGI-X8 resin in 4 M hydrochloric acid zinc has a distribution coefficient of ca. 400 and is completely retained. Danilin et al.“3’ and Gruverman and Kruger”” apparently did not investigate the separation of ssFe from 6’Zn. Moreover. by covering the copper-base with a silver layer and electroplating the manganese onto the silver the amounts of iron, copper and zinc impurities can also be reduced significantly, because highly pure silver can be used and only traces of silver should dissolve in 5M hydrochloric acid. No other radionuclides should thus be introduced into the etching solution.
from manganese target material
22,529 (f. 1.3%)
Percentage of total activity -
CO.05
22,870 ( & I .4%) cl0 < 10 < 10
loo’, CO.05 co.05 CO.05
“Fe activity (counts/4OO 5)
“Other
161
Technical Note References
Table 2. Manganese. copper. zinc aod iron impuritiesin &al “qe**
fraction Total mount Element
Cold target
Mtl cu Zll Fe
CO.1 0.1 co.1 48
of elancttt @g) found Heat-treated
target
0.4 0.6 co.2 35
The yield of rsFe was better than 99”/, (Table 1) and no significant losses could be measured in the other eluate. on the glassware, the funnel or the resin column. Less than one microgram of manganese, or copper, and only between 48 and 55 pg of iron were found in the “‘9Fe” fraction (Table 2).
1. Mendel B., Hawkins R. D. and Nishikawara M. Am. J. Physiol. 154, 496 (1948). 2. Beinert H. Science 111, 469 (1950). 3. Gabrio B. W., Shoden A. and Finch C. A. 1. Biol. Gem. 204. 815 (1953). 4. Wolff R. H., Henderson M. A. and Eisler S. L. Plating 42, 537 (1955). 5. Gruxin P. L. and Zemskii S. V. Zovodskaya Lab. 22,169 (1956). 6. Mori M. and Tsuchiya R. Nippon Kagaku Zarshi 77, 1525 (1956). 7. Zemany P. D. Rec. Sci. Instr. 30, 292 (1959). Lederer M. Actual. Sci. fnd. No. 1240, 64 pp (1956). ;: Proso 2. and Pucar 2. J. Radioanal. Chem. 2, 243 (1969). 10. Danilin L. D. and Pavlova-Verevkina A. I. Radiokhimiya 16, 128 (1974).
COllCl~OO The separation of “Fe from manganese cyclotron target material by anion exchange chromatography in 9.0 M hydrochloric acid using a 2% cross-liked resin is sharp and quantitative. Separation of jJFe from cyclotron bombarded manganese targets should be of comparable quality because both isotopes behave chemically in a similar way. The described method can produce J5Fe of high purity, with a yield of 95% or better under routine production conditions.
A.M.
W?--E
11. Kvastek K., Strohal P. and Despotovic R. Croat. Chem. Acta 3& 317 (1966). 12. Danilin L. D. and Pavlova-Verevkina A. I. Radiokhimiya 15, 223 (1973). 13. Danilin L. D., Druxhinin A. A. and Pavlova-Verevkina A. I. Radiokhimiya 8, 712 (1966). 14. Gruverman I. J. and Kruger P. Inc. 1. Appl. Radiat. Isot. 5. 21 (1959).
15. Walt T. N. van der, Strelow F. W. E. and Haasbroek, F. J. Talanta In press.
1985
0020-708Xi85 53.00 + 0.00
Separation of Iron-55 from Manganese Cyclotron Target Material on a 2% Cross-linked Anion Exchanger in Hydrochloric Acid f. N. VAN DER
WALT’, F. W. E. STRELOW’ and F. J. HAASBROEK’
‘National Chemical Research Laboratory and ?National Accelerator Centre, P.O. Box 395, Pretoria 0001. Republic of South Africa (Received 25 June 1984) A simple method is presented for the separation of iron-55 from manganese cyclotron targets. Anion exchange chromatography with 9.0M hydrochloric acid on a 20/, crosslinked resin provides separation not only from large amounts of managanese but also from copper and zinc impurities. Separations are sharp and quantitative and less than I pg of manganese remains with the iron-55 when 2 g have been present originally.
Introduction Iron-55 (I,,? = 2.6 y) can be obtained from manganese targets by the 55Mn(d, 2n)“Fe reaction through cyclotron bombardment. It is used medically”-” and in industrial metallurgy.+” Various separation techniques have been described by several authors involving paper chromatography,“’ continuous electronhoresis,‘9’ electrochemical procedures,“““’ extraction(‘2’ aid anion exchange chromatography.“‘.‘4) Danilin et al.“‘) ourified the $jFe isotooe obtained in a reactor from oth& radioactive elements (mainly %Mn and 6oCo) by using Dowex 2-X8 anion exchanger in 8 M hydrochloric acid. Gruverman and Kruger”41 separated cyclotron produced j’Fe from manganese on the anion exchanger Dowex l-X8. JJFe is retained while manganese is eluted from the column with 4N hydrochloric acid. Previously “Fe had been separated from the manganese target material in this laboratory by extraction with diisopropyl ether from 8 M hydrochloric acid. The manganese target used in the Pretoria cyclotron consists of a manganese layer electroplated onto a watercooled copper base. UZn is formed by the reaction “Cu(d 2n)6JZn (t = 244d). To prepare radiochemically pure s;Fe with nzcarrier added, separation from zinc and copper has to be included in the procedure. The separation of iron from copper is not very satisfactory with a 8% cross-linked resin when eluting with 4 M hydrochloric acid because of tailing. From known distribution coefficients”J) it appeaxed that by using a 2% cross-linked resin a considerably improved separation of iron from copper and manganese and a good separation from zinc should become possible. This was investigated in detail and a new procedure for the separation of $‘Fe from manganeK cyclotron targets has been developed and is presented.
Experimental Reagents and apparatus Analytical reagent grade chemicals were used and purified from iron by anion exchange chromatography. “Suprapur” 159
reagent grade hydrochloric acid was used. Water was distilled and further purified by passing it through an Elgastat deionizer. Freshly prepared hydrogen iodide was obtained by passing a solution of potassium iodide through a cation exchanger and eluting hydrogen iodide with water. The resin used was the AGI-X2 polystyrene anion exchanger with quatemary amine exchange groups, supplied by Bio Rad Laboratories, Richmond, California. A borosilicate glass tube (IO mm bore and I50 mm long) which was fitted with a fused-in No. I porosity glass sinter and a tap at the bottom and was joined at the top to a borosilicate glass tube (20 mm bore and I50 mm long) as a reservoir, was used as a column. The column was filled with a slurry of resin until the settled resin reached a mark at 4.4 mL ( I I .Og dry resin) and eauilibrated with IO mL of 9.0 M hydrochloric acid. Be&se the 55Fe activities are difficult- to measure the J9Fe radioisotope and a non-radioactive manganese cyclotron target were used to simulate the etching procedure and the separation of jSFe from the manganese target material. Atomic absorption measurements were carried out on a Varian-Techtron AA-5 instrument. A 4096 channel Multichannel Analyzer, coupled to a Ge(Li) detector was used to identify the s9Fe radioisotope and to measure the activities. An automatic Aimer Central fractionator was used to collect fractions for the preparation of the elution curve. Elution curt-e A solution of I00 mL of 9.0 M hydrochloric acid containing 2.0 g of manganese, I .Og of copper, I .Omg of zinc and l.Omg of iron(III) was prepared. The solution was passed through a resin column containing 4.4mL (= 1.0 g) of AGI-X2 resin of 100-200 mesh particle size, which had been equilibrated with 9.0 .M hydrochloric acid beforehand. The elements were washed onto the resin with small portions of 9.0 M hydrochloric acid, and manganese, copper and zinc were eluted with more 9.0 M hydr&hloric acid (150 mL in total). Iron(II1) was then eluted with 50 mL of 0.1 M hydrbchloric aiid. The flow-rate was 4.0 f 0.3 mL/min and IOmL fractions were collected from the beginning of the sorption step. Those fractions containing 9.0 M hydrochloric acid were evaporated to dryness on a waterbath and the salts were dissolved in IO mL of 0.5 M hydrochloric acid. T’he amounts of manganese, copper, zinc and iron were determined by atomic absorption spectrometry, using the air-acetylene flame and the 219.5,324.8,213.3 and 248.3 mn lines for manganese, copper, zinc and iron respectively. The experimental curve is presented in Fig. I. Separation of iron-59 from manganese target material A non-radioactive manganese target was etched in an etching cell with 10 ml portions of 5.0 M hydrochloric acid containing 0.3% hydrogen peroxide. Finally, the cell was rinsed with water. The acid and wash water were evaporated to cu. 20mL. An accurately measured amount of ve activity was added to this solution. The resulting solution was filtered through a No. 2 porosity glass sinter funnel and the beaker and funnel were washed with 0.5 M hydrochloric acid. The filtrate was evaporated to ca. IOmL volume, cooled, and mixed with IlOmL of concentrated hydrochloric acid (“Suprapur”). The solution was passed through an equilibrated AGI-X2 resin column (as described above). The elements were washed onto the resin with small portions of 9.0 M hydrochloric acid. “Fe was retained on the resin and the other elements were completely eluted with 9.0 M hydrochloric acid, using 100 mL in total. Finally, j9Fe was eluted with 30 mL 0. I M hydrochloric acid. The eluates were evaporated to ca. 2 mL and transferred to IOmL containers with the aid of small portions of 0.1 M hydrochloric acid. j9Fe activities were measured on the funnels,
160
Technical Note
i \ a
(2”6;
E * o.s-
i
CU 11gl
Fe(E) $lYg, ‘x /
h5
\
, “\
XIX
0
‘I
X
100
200 Eluote
300 (mL
Fig. I. Elution curve Mn-Cu-Zn-Fe(II1). 4.4mL (I 1.0 g) AGI-X2 (Cl-form. length 55 mm, I#IIO mm. Flow-rate 4.0 k 0.3 mlimin.
glassware, resin column, and in the eluates and in the “Fe eluate. The results are presented in Table 1. Determination of impurities in the “s9Fe fraction”
Two similar experiments as described above were conducted, but without the “Fe radioisotope. In one case the target was heated in a vacuum pistol at ca. 250°C for 2 h in order to simulate the conditions for the target in the cyclotron. The amounts of manganese, copper and iron were determined in the “Fe fraction by atomic absorption spectrometry using the conditions described above. The results are presented in Table 2. Results and Discussion In the described procedure analytical reagent grade chemicals were used for the preparation of the cyclotron target. Iron, lead, zinc, nickel and other impurities were all less than 10 ppm. Manganese was further purified by electroplating it on a copper base when preparing the cyclotron target. In actual cyclotron bombardments, preparing up to 400 mCi of “Fe per bombardment, no other radionuclides were detected with a multichannel analyzer (probably because of
Table 1. Results of JPFe separated
Fraction qe
used for separation element” &ate elutcd with 9.0 M HCI Iron-59 eluate eked with 0.1 M HCI Resin column Funnel t-&Is.%-ware
400
1 100-200 mesh). Column
the very small quantities of impurities present in the manganese target). Furthermore, according to the distribution coefficients for copper (K,, = 3.4) and manganese (K,, = 4.5),“” residual traces of these elements should easily be eluted from the AGI-X2 resin column with 9.0 M hydrochloric acid. The elution curve experiment (Fig. I) confirmed this. Zinc was completely eluted from the resin column although it has a relatively large distribution coefficient (& = 39.9).“” A distribution coel&ient value of ca. 40 had also been obtained for zinc on the anion exchanger AGI-XI in 12 M hydrochloric acid, but zinc could not be eluted completely from this resin because of serious tailing. With AGI-X8 resin in 4 M hydrochloric acid zinc has a distribution coefficient of ca. 400 and is completely retained. Danilin et al.“3’ and Gruverman and Kruger”” apparently did not investigate the separation of ssFe from 6’Zn. Moreover. by covering the copper-base with a silver layer and electroplating the manganese onto the silver the amounts of iron, copper and zinc impurities can also be reduced significantly, because highly pure silver can be used and only traces of silver should dissolve in 5M hydrochloric acid. No other radionuclides should thus be introduced into the etching solution.
from manganese target material
22,529 (f. 1.3%)
Percentage of total activity -
CO.05
22,870 ( & I .4%) cl0 < 10 < 10
loo’, CO.05 co.05 CO.05
“Fe activity (counts/4OO 5)
“Other
161
Technical Note References
Table 2. Manganese. copper. zinc aod iron impuritiesin &al “qe**
fraction Total mount Element
Cold target
Mtl cu Zll Fe
CO.1 0.1 co.1 48
of elancttt @g) found Heat-treated
target
0.4 0.6 co.2 35
The yield of rsFe was better than 99”/, (Table 1) and no significant losses could be measured in the other eluate. on the glassware, the funnel or the resin column. Less than one microgram of manganese, or copper, and only between 48 and 55 pg of iron were found in the “‘9Fe” fraction (Table 2).
1. Mendel B., Hawkins R. D. and Nishikawara M. Am. J. Physiol. 154, 496 (1948). 2. Beinert H. Science 111, 469 (1950). 3. Gabrio B. W., Shoden A. and Finch C. A. 1. Biol. Gem. 204. 815 (1953). 4. Wolff R. H., Henderson M. A. and Eisler S. L. Plating 42, 537 (1955). 5. Gruxin P. L. and Zemskii S. V. Zovodskaya Lab. 22,169 (1956). 6. Mori M. and Tsuchiya R. Nippon Kagaku Zarshi 77, 1525 (1956). 7. Zemany P. D. Rec. Sci. Instr. 30, 292 (1959). Lederer M. Actual. Sci. fnd. No. 1240, 64 pp (1956). ;: Proso 2. and Pucar 2. J. Radioanal. Chem. 2, 243 (1969). 10. Danilin L. D. and Pavlova-Verevkina A. I. Radiokhimiya 16, 128 (1974).
COllCl~OO The separation of “Fe from manganese cyclotron target material by anion exchange chromatography in 9.0 M hydrochloric acid using a 2% cross-liked resin is sharp and quantitative. Separation of jJFe from cyclotron bombarded manganese targets should be of comparable quality because both isotopes behave chemically in a similar way. The described method can produce J5Fe of high purity, with a yield of 95% or better under routine production conditions.
A.M.
W?--E
11. Kvastek K., Strohal P. and Despotovic R. Croat. Chem. Acta 3& 317 (1966). 12. Danilin L. D. and Pavlova-Verevkina A. I. Radiokhimiya 15, 223 (1973). 13. Danilin L. D., Druxhinin A. A. and Pavlova-Verevkina A. I. Radiokhimiya 8, 712 (1966). 14. Gruverman I. J. and Kruger P. Inc. 1. Appl. Radiat. Isot. 5. 21 (1959).
15. Walt T. N. van der, Strelow F. W. E. and Haasbroek, F. J. Talanta In press.