Sample Analysis During the reporting period, LASL-H7 has performed approximately 100 analyses for 238), 2354 , and 90 240 Pu; 200 analyses for Sr; 60 scans from which 2344, 150 analyses for 2385 ang 739° 100 analyses for 241sn, and 100 gamma Co and 1376. were determined. Uranium Procedure Developemnt During this same time period, a procedure to prepare alpha spectrometrically pure U plates from soil or large vegetation samples was developed. This effort is still in progress. However, a tentative procedure has been finalized and is being used to analyze NAEG soil and vegetation samples. Most of the available procedures work quite well on solutions of low dissolved solids content, are long and involved, or are designed for fluorometric measurement of total U and produce an unsatisfactory plate for alpha spectrometry. With the "tentative" method, small amounts of U can be isolated from a 10-g sample of soil or a 30-50 g sample of dried vegetation, in the presence of relatively large quantities of Pu and other interfering alpha emitters. The main interfering element is Fe, naturally present in the sample matrices to such an extent that serious alpha spectrum degradation occurs if Fe is not removed. Alpha spectrum interferences are avoided by this procedure since Pu, Am, Th, and most other alpha emitters are either removed from the sample or have alpha energies that do not interfere with the various natural or weapon U isotopes. As shown in the flow diagram (Fig. 1), the procedure includes (1) soil sample digestion by the LASL-HASL HF-HNO,-HC1 acid method, or vegetation digestion by the LFE method, Matrix mass by Fe scavenging, (2) removal of much of the (3) ion exchange separation of U from most other elements which might interfere, (4) ether extraction to remove Fe, and (5) electrodeposition of U for alpha spectrometry using 232 U as a chemical yield tracer. 18