Statistics. reported results and errors are those For those nuclides with multiple sample determinations, of the simple average. the Quality-Control Program SAMPLE ALIQUOT © Results from dissolution of the 25-g aliquots are compared in Table 7 The usual MCL quality control with those from the smaller aliquots. program was expanded to examine the The ratio of results from carrier validity of wet-chemistry analysis to carrier-free dissolutions is of small sample (3 to 5 g) aliquots. given for each of the atom ratios and Specifically questioned was whether isotopic concentrations. the small aliquots were representative reported with each entry result from of the larger sample. propagation of uncertainties in the homogenized samples, For wellthe small ali- individual measurements. quots were known to be representative. —— Twenty-seven samples (5 vegetation Errors Soil samples from both Bikini and Eneu show excellent reproducibility in all major and 22 soils) were selected for isotopes. carrier-free dissolution of 25-g spectrometric measurement of minor aliquots. isotopes such as The term carrier-free Past experiences in mass tou would lead describes working solutions obtained one to expect an even greater spread by the dissolution of sample in the than that observed. absence of appropriate carriers and results are reproducible to within tracers. 10 percent is quite encouraging. The major difference between The fact that the For the carrier-free and standard carrier the soils there is no indication of dissolutions was the absence or a statistically significant bias presence of the carriers and tracers resulting from the use of small in the working solution. Processing 24 of 70.4 r, Pu and Tam samples from the (5 g) sample aliquots. carrier-free solution was accomplished of samples of vegetation indicate by adding Y carrier and 2 tracer to one aliquot and Comparison of the measurements Pu mass the possibility of a slight bias Am to in the dterminations of 990, and 43 another, achieving isotopic exchange 239,240), .. in the solution, and proceeding with are not significant at the 95 percent the standard methods for separation confidence level. and purification. definite indication of significant -13- 5010055 however, these biases There is a