DE1943416C3 - Method of making radioactive barium - high 137 m - Google Patents

Description

The invention relates to a process for the production of radioactive barium- ¹³⁷ " ¹ in high yields and of a high degree of purity.

Barium- ¹³⁷ " ¹ is the daughter nuclide of cesium-" ⁷ . It is known that barium- ¹³⁷ " ^{1 is} an extremely suitable isotope for medical research and diagnosis. It is particularly suitable for examining flows, for example blood flow velocities. As a result of its relatively short half-life of 2.6 minutes, barium - ¹³⁷ " ¹ can be administered safely in multicurie quantities with a very limited radiation dose. This is especially important when a clear, sharp scanner diagram is desired. Due to the short half-life of barium- ^117m , it is also of interest for teaching purposes.

For example, students can determine core properties for a limited period of time using an unshielded ^{low activity barium-137} " ¹ generator. Barium- ¹ · ¹⁷ " ¹ can also be used for various other purposes where a short half-life is desired is.

Various working methods have been used to manufacture generators for barium- ¹³⁷ '". For example, JJ Pinajian, J. Chem. Educ. 44, p. 212, (1967), cesium- ¹³ ' adsorbed onto zirconium phosphate and extracted barium- ¹³⁷ " ¹ with 1N salic acid in a yield of approximately 20 percent. M.Blau et al., Nucleonics 24, p. 60 (October 1966) made a barium ^37m generator using a mixture of ammonium molybdophosphate and Asbe-Ji. About 50 allspice of the barium ¹³ "" were eluted using 0.1 η hydrochloric acid. A. Bonni et al (French patent 1 302 506), use copper ((irhexaL> ano-ferrai (l!) And recover 12 to 20 percent of barium- ¹³⁷ " ¹ in bariumnitnu solution.

From these generators, however, barium- ¹³⁷ " ¹ is not reproduced in physiological, isotonic salt solution, water or dilute hydrochloric acid solution.

lü winable, so that an additional chemical treatment of the eluent for the purpose of use for intravenous L-n injections in humans or for other investigations is necessary. This additional chemical step is of ^{course undesirable for barium-137} " ¹ , since it decomposes quickly. In addition, the yield of barium- ¹³⁷ " ¹ from the previously known generators was low.

The object of the invention is therefore to provide a more effective process for the production of radioactive Harium- ¹³⁷ " ¹ with a high degree of purity, which can also be used for medical research and diagnosis.

The erriiKhingia'emiform process for the production of radioactive 'Barnim- ¹³⁷ " ¹ , in which ¹³⁷ Cs and

As its Tochenuil-iid Ba ^{l37m bound} to a ferrocyanide Si hstrat and the barium isotope selectively from the substrate ek.ici and, is characterized in that a kokiiiüviooanid of the following general Κ ·· πίκ-Ι

Ni [CoIe (CN) ₈ ]

in soft M \ ick.-l. / mk, iron (II) or copper (II) means, au a leniperatur of 50 to 100 ⁰ C heated, after this pretreatment with a reductioninittc! and is ^{contacted with a 137} Cs-containing molar salic acid solution, whereupon the loaded substrate is in the presence of a ¹³⁷ Cs selectively retaining filter aid with physiological salt solution or a weakly acidic aqueous solution, in particular with 0, In-HCl or 0, In - ENT ,, treated.

^{Radioactive barium-137} " ¹ produced by the process according to the invention is obtained with a very high degree of purity and is therefore suitable for use in medical research and diagnosis. In contrast to the known working methods mentioned, the process is extremely simple and fast, whereby it delivers a high yield of barium. In addition, the solution of the eluted barium isotope is free of undesired ions and organic components in contrast to solutions obtained by known methods. Finally, the relatively short half-life of this isotope can be fully exploited, since further chemical purification of the Eluent is not necessary.

^{The cesium-11} 'used as the starting material is commercially available and is obtained as a fission product of uranium. The purification of the cesium ¹³ 'before it is used for the method according to the invention can also be carried out according to known chemical procedures. The cesium- ¹¹⁷ is then contacted with a cobalt ferrocyanide of the formula given above. Copper (II) hexacyano-cobalto (II) ferrate (II) is

65 preferred.

In practice, the cesium- ^{137 is,} for example, dissolved in a suitable solvent and the solution obtained with the hexacyano-cobaltodlV

943416

brought into contact.

is

Vir,. ·

; .-. i to depress,
, i-koballo (! l) -ferra! (!! i '

• -on about 50 to lüi / C for a fixation ', or · weni ·' -. -; wa 2 me, in heat. ' ^c

Suitable solvents are water or aqueous an inorganic acid, unprecedented; -Hydrochloric acid. Hydrochloric acid wi, -J m ^.,> Ridere hevorv, eil the breakthrough of Cae> simi on a mini. is reduced. If heispiekweiv-0 1 n- ^v air.aure is used wild, a cesium diameter of about 0.3 per cent is found. If ch 0.1 η-hydrochloric acid is used "let him!" Reduce fraction to about 0.01 percent.

^; ai to avoid that the production -, on Ba- _{: ir} .u7m _from the generator decreases with time from ungei ".. ·.! · 90 percent to about 20 percent during the period of 2 months, the J.uk -ne substrate with a reducing agent, examples ■;.... ■, .- IiWeise graphite, carbon black, charcoal od the like, passes this measure, the yield remains' .: barium ¹³⁷¹ "during the life of Gene-M- ors to a value of 95 percent. The reducing agent is usually used in an amount of from 5 to 60 percent, preferably from 1 to 40 percent, based on the weight of the hexacyano-kobaiio (II) ferrate used ( II).

In order to ensure a high degree of purity of the eluted ba _[ilim .i37m, a filter aid is used to prevent contamination of the eluent by (aesiurn- ¹³⁷ .

^L: s, a plurality of filter aids used for this purpose but each Werder anion exchanger, such as hydrated zirconium oxide, especially suitable for this purpose. The anion exchanger can be arranged in the generator below the loaded substrate in order to filter out ^{any undesired cesium-137.}

The purity of the barium ^solution obtained from such a generator is high; they contain about 2 · 10 "* percent cesium- ¹³⁷ and less , \ h 1 ppm iron, cobalt, copper and cyanide ions.

After the production of the ^{cesium-1 '7} containing substrate is transferred by this into a suitable elution system, for example in a column or a container, preferably made of glass or another inert material. The system is washed with water, the supernatant liquid is drained off or removed by filtration or decantation. The substrate is then eluted with 0.1N hydrochloric acid or washed first with isotonic salt solution and then eluted with additional amounts of this salt solution.

The process of the invention is a simple method for the production of barium- ¹³⁷ " ¹ in high yield. According to the process, the recovery of barium- ¹³⁷ " ¹ with isotonic salt solutions in yields of 90 percent and higher without dissolving the substrate or removing any significant Amounts of cesium can be carried off the substrate.

The following examples illustrate the invention. example 1

■ This example illustrates the manufacture of high purity barium- ¹¹ ' ¹ "which is suitable for use as an aid in medical diagnosis.

ιπ jeü'i-hrii Dt: r <-S- 5 _n , j a löpiozentigen potassium hexacyanofer-

> - '-L-luentcn on a rat; lI) solution and 0.5 ml of 1N acidic acid become 3 g of>' -Hiiiif !, the; | i: xj- hydrated zirconium oxide with a grain size of ¹ 1/2 to 0.074 mm mesh size given. The slimming is carried out well and transferred to a column provided with a glass frieze and an internal diameter of 1 cm. Then 2t) with an Ipmzeniigen copper (l!) Su! Fat! Ö? I; ng> nO ,! n-hydrochloric acid and 50 ml of water successively through the

ίο lonne sent. The UUV thus deposited on the zirconium oxide liydrüisierten KupiertII) -hexacyanofe ^r ranll) serves as a filter for cesium ^537th

The main part of the generator, the copper-oil form of Hexacyanokobaiio (O-ienaUIi), which ^{adsorbs 137} Cs and. Barium ¹¹⁷ " ¹ egg is made in the following way:

10 ml of a 10 percent copper (li) suirail solution in 0.1 N hydrochloric acid are added to 1 ml of a solution of commercially available potassium hexacyano-kobaitoOiHerrat · '!!)

ao given. The slurry is ^{heated to about 80 °} C. for 30 minutes. After cooling, the supernatant solution is decanted and the solid phase is washed three times with water by decanting. ^{1 m-Ci 137} Cs in 0, In-hydrochloric acid are added to the copper (H) form of hexacyano-cobalto (Ii) -ferraUll) obtained in this way. The slurry is heated for about 30 minutes at 85 to 9O ⁰ C and allowed to cool 30 min. Then 0.4 g of graphite particles with a grain size of 0.84 to 0.30 mm mesh size are added and mixed with the slurry. The mixture is ^{transferred to the column containing the cesium 137} filter and the column is washed with 100 ml of physiological saline solution. Both ends of the column are closed with rubber lids and aluminum compression caps. One end of the generator connects to a supply line for physiological saline solution and the other end to a collection bottle. Before the solution flows into the receptacle, the line is connected to a fine-pored filter unit. Barium- ¹³⁷ " ¹ is obtained in the collecting bottle by washing the column with additional quantities of the physiological saline solution.
Table I shows the adsorption elution properties

«I shafts of the ^{1> 7in} Ba generator.

Table I.

Adsorption-elution properties
of the ^{1> 7m} Ba generator for medical purposes

55 Extraction of ^137m Ba in 0.7 meq / ml ¹ ' ⁷ Cs adsorption capacity 10 ml of physiological salt Copper <ll) shape
by Hexacyano- solution . . . kobalto (U) -ferrat (lI) 60 Extraction of ^II7m Ba in 10 ml of 0.1 N hydrochloric acid Extraction of '»" »Ba in 83 ± 7 ° / « 10 ml of water ** * -L- ' IQ ¹³⁷ Cs breakthrough 85 -Jb ΙΟ "/, 63 total salary of heavy metals 10 to 40 "I ₀ Cyanide ions <to ~ * ° / _e radiation chemical effect .. ~ 1 ppm <0.5 ppm none

Example 2

This example illustrates the preparation of barium ¹³ '^"1, wherein the isotope is not necessarily of high purity £ v' must i), such as for iJnierrichiszweike or industrial applications. An activity of 100 In-C'i ¹³¹ Cs on the Kupierillj- Forni of hexacyanu-kobaIto (H) -ferrate (lI) adsorbed in the same way as described in Example 1. Then a small part of the substrate, which contains 1 m-Ci ¹³⁷ Cs, is transferred to a small commercially available filter unit Radioactivity is set to a desired value by counting it using a detection device, for example a gamma-ray scintillation counter or a Geigei-Müller counter tube. The feeding unit is then closed, connected to a syringe containing an eluent and eluted. Table II shows the elution characteristics ( ! '.>% Generator. If physiological saline solution is used as a source, an occasional treatment with acid, for example once in j At times a 2-month interval with Ο, ΐη-hydrochloric acid is necessary to maintain a high value of the ^{13 m} Ba-Ausbe> ite.

Table Il

Elution properties of the ¹³ ' ^m Ba-Oenerafors for research purposes or industrial applications

^{l; n} -Cs adsorptive capacity

Obtaining ^{! 37m} Ba in 5 ml Ο, ίη-hydrochloric acid

Extraction of ¹³⁷¹ ^ Ba in 5 ml of 0.1 η-nitric acid .. '5 Extraction of ^137m Ba in 5 ml of physiological saline solution ...

Extraction of ¹³⁷⁰¹ Ba ^; n 5 ml of water

^la 'Cs-Üurchuch

Total heavy metal content

Cyanide ions

0.7 maq m! on

Copper (U) shape

by Hexacyano-

koba! toili) -ferrct (lli

85 i 10% 85 ± 10 ° / ₀

85 ± 10 ° / _e

10 to 40 ° / ₀

0 '/ 0

-0.01 ° '

; 10 ppm none

Claims (4)

Patent claims: 1. A process for the production of radioactive "barium- ¹³⁷ " ¹ , in which ¹³⁷ Cs and its daughter nuclide Ba ^{137ra are bound} to a ferrocyanide substrate and the barium is3top is selectively eluted from the substrate, characterized in that a cobalt ferrocyanide of the general form H below M [CoFe (CN) ₆ ] in which M is nickel, zinc, iron (II) or copper (II), heated to a temperature in the range of 50 to 10O ⁰ C, mixed after this pretreatment with a reducing agent and a molar with a ¹³⁷ Cs haItigen 0.1 hydrochloric acid solution is contacted, whereupon the loaded substrate is treated with physiological salt solution or a weakly acidic aqueous solution, in particular with O, In-HCl or O ₁ In-HNO ₃ , ^{in the presence of a filter aid which selectively retains 137 Cs.} 2. The method according to claim 1, characterized in that the substrate copper (II) -hexacyano-cobalto (11) -ferrate ( 11) is used. 3. The method according to claim 1 and 2, characterized in that there is used as the reducing agent Uses charcoal. 4. The method according to claim 1 to 3, characterized in that hydrated as filter aid Zirconia used.