ry a Ra Fa . 239. L { er6n, 576 Mev 2287, r a = 5 43 Mev r = %S ; or v = i a - : ~ 224 Pa 566 Mev . WMAP TH reg TAO: ~ 63 i Bo Channe! i ze ! No Fig. 1. 2-Spectrum of ?39Pu, °?8Pu, ?2°Pu, °°8Th and 27+Ra, Thorium. however. does follow plutonium in the hydroxide precipitates and is not effectively cleaned up by the nitric acid elution (necessary for separation of iron from plutonium) on the anion-exchange column. nor. on this column. by hydrochloric acid elution: Stubborn traces of thorium continue to elute atter many column- RESUME ] des éch sensibil 100 g)e par cor nitrique adheres until eluted with hydrochloric acid-ammonium iodide whereas thorium Is ZUSAMM quickly washed out with concentrated acid. tamer tepee Jarge sa per 100 sample, hydrox water. ; sedime! and bla volumesof this acid. This is probably because of strong adsorption of thorium-nitrate complexes in the interstitial cavities of the resin beads, where the hydrochloric acid wash may be physically restricted. Use of a second anion column, equilibrated with hydrochloric acid, has proved necessary and effective: On this column plutonium Other parameters Two kindsof material, platinum andstainless steel, were studied for the mount- ing of plutonium for a-spectrometry. Stainless steel discs were chosen because they are considerably less costly than platinum and the quality of the plated sample is not significantly different from thatof the platinum disc in terms of both a-resolution and adhesion of plutonium to the plate. Theresolution ofthe spectrometer used for the 5.76- MeV x-emission of 73° Puls 60+ 5 keV (FWHM) on stainless steel discs as compared to 65+5 keV for platinum Anal. Chim, Acta. 36 (1971) 35 5-364 500u281 ment. contrac 548 Mey Lf cal r directh <36p. t f standa ~ counte SUMMA! HE bF Know! beaker Institut 4, L 5 e 4 53 aM vs ~ ) pe p — PE en ere ee * 515 Mev ~ . [ I | - «2a yee deel Hit ak Sok ihe oh inltaco tei tate — ail en Te tans Maal, Mecca: wd discs. . detect than il T fT as 228Th. which is present. as a decay product. in the ~*°Pu tracer. as well as being very rich in most recent marine sediments. and detectable in marine organisms. Radium224 is no problem in the method described since 11 does not follow plutontum in the hydroxide precipitation. ‘ geometry. of thorium-228. and radium-274 in this energyregion. [tis clear that -** py. the least abundantof the plutonium isotopes measured, is seriously interfered with by Tecan apsed teh ee 7 ees acl. : ee: ve lee PLUTO kh. M. WONG cr rapa Lie ict Paes ba nit bl we ini ar, aed: oh = baa 362 Divers | I grossen lichkeit in Sedin Probe) t wird ein aschte C zogen. [ b-einflu