Allowing for Trace Uranium Leaching From Glass Fibre Filters During Sample Dissolution†

Abstract

The amount of uranium leached from glass microfibre filters used to collect samples of dust, by the subsequent dissolution of the sample in mineral acid, was not normally distributed, so the mean of several replicate blank determinations was not a reliable estimate of the reagent blank for individual sample analyses. The leached blank values appear in a repeating sequence of 10 through the filters as they are stacked in their original boxes. Ten filters should be taken to determine the procedure blank, and the distribution of the 10 values should be reviewed if the blank is a significant factor in the analysis; a set of well-behaved blanks could be assembled by taking every tenth filter from undisturbed boxes of one batch lot. In contrast with this leachable fraction, the bulk concentration of uranium in the filters is consistent through a batch lot.