In the case of soils, Sill recommends further Wessman et al. (1971) reported on a method for trace plutonium analysis in a large variety of sample matrices and this system formed the basis for the determination of the other transuraniums, as later reported (Wessman et al., 1977). A schematic diagram of the procedure is given in Figure 5. The first steps of the procedure, which are adequate to solubulize and equilibrate Pu, are also adequate for any other transuraniums present. Yield tracers are 233pq (234Np) for eaNe 236py for 238py, 239°240py and 24%3am for the combined | group consisting of 7"lam, 22cm, and 243*244em, An anion exchange column (Dowex 1-X4) is used to absorb Np (IV) and Pu (IV) from 8 N HNO3 while Am (111) and Cm (III) pass through the column, Plutonium ie separated from Np on a subsequent Dowex 1-X4 ion exchange column. The column is washed with 8 Plutonium is eluted with NH,I-HCl and Np with 2 N HCl. NEPTUNIUM PURIFICATION Magnusson and LaChapelle (1949) discussed the procedure devised by Seaborg and Wahi (1948) to isolate weighable quantities of 23’Np for further study. The classical reactions were used, mostly lanthanum fluoride precipitations to carry Np (IV) or Np (III). Impurities, such as Pu and fission products, were precipitated with LaF; in the presence of Np (VI). Burney and Harbour'’s 1974-monograph on the Radiochemistry of Neptunium has a very complete discussion on the more recent aspects of Np chemistry including solvent extraction and ion exchange, They point out that Np is easily converted in aqueous solution to oxidation states that exhibit markedly different behavior in coprecipitation, and therefore separation from other elements can be obtained. They further note that the fon exchange, extraction chromatography, and solvent extraction separation are used almost exclusively because more complete separation is attained more rapidly. Burney and Harbour presented a collection of 25 procedures, Fifteen are for a combination of the different separation steps on highly radioactive samples, three are for environmental and biological samples, and seven are for quantitative elemental determinations. Two of the procedures for highly radioactive solutions use either 73’Np or 73°9Np as tracers. None of the 237Np environmental or biological procedures given use 556 557 x 4 The Am, Cm-containing eluant is further purified using steps which have been pretested to assure that Am is not fractionated from Cm. Figure 6 shows an elution curve obtained in testing the final cation exchange column step in the procedure. In actual analyses, the fractionation of Am and Cm is usually within 2 to 3% of each other. *Private communication with K. M. Wong. R.E. oxalate, Am Fp C2 O4 PH 1-2 N HNO3 and HCL. dissolve in 2N HCl IS NH,OH (hydroxides) Conc. HCl ! 8N HNO; Fe, Sb, RE, Am (partial) elute through Dowex dissolve in HNO, adjust to 8N in HNQ Fe, RE, Sb, Pu 3-5 dpm standardized 2 *pu tracer | NHLOH ’ (hydroxides) | Combine R. E. fractions NH, -HC! superhate) Cs, Sr Process a reagent blank after every eight samples. separation of the tervalent actinide group from the lanthanides according to the method of Filer (1974). The Latter procedure combines extraction chromatography with bis(2-ethylhexyl)-phosphoric acid (HDEHP) in the presence of diethylenetriaminetetraaccetic acid and the use of a column of Teflon-6 powder. Siil further recommends, when necessary, Moore and Jurriaanse's (1967) method to separate *"2cm from 252C£ whose alpha energies are so identical, alpha spectrometry cannot resolve them. 500 mg Fe (unstandardized) 10 mg each of standardized Sh, Ce, Nd, Sm, Eu, Y and Cs 2 g standardized Sr FIGURE 4 WONG, NOSHKIN AND BOWEN'S PROCEDURE AS APPLICABLE TO THE ANALYSIS OF Pu AND Am* IN SEAWATER SAMPLES Ref: Methods for Marine Radioactivity Studies, IAEA, Vienna (1970), p 119. back-extracted with 8 M HNO3.