Source of uranium process blank in the bulk analysis of safeguards environmental samples

Tomita, Jumpei  ; Tomita, Ryohei ; Suzuki, Daisuke   ; Yasuda, Kenichiro   

Low uranium process blank is needed to accurately determine uranium isotope ratios of the safeguards environmental samples. However, more than 10 pg of the uranium was sometimes observed as the process blank through the sample decomposition procedure. In this study, the sources which increase the uranium process blank through this procedure was investigated. The input of the uranium was found in the wet ashing procedure using HF. Leaching experiment of Pyrex hood covers used to collect vaporized acid showed that they contain much uranium. These results indicated that uranium supplied from Pyrex glass weathered by HF was the main source of the uranium process blank through the samples decomposition.