Sequential separation of ultra-trace U, Th, Pb, and lanthanides using a simple automatic system

Abstract

Uranium, thorium, lead, and the lanthanides were automatically and sequentially separated with a single anion-exchange column. This separation was achieved using eluents consisting of a simple and highly pure acid mixture of HCl, HNO3, acetic acid, and HF. The elements of interest were separated from the major constituents, which included alkaline metal elements, alkaline earth metal elements, and iron. This simple and automatic system is driven with pressurized nitrogen gas and controlled using a computer program. An optimized separation was accomplished under the following conditions: a 50 mm long and 2 mm diameter column, 11 μm diameter anion-exchange resin, and a 35 μL min(-1) flow rate. Using this system, 50 ng of varied elements in a 100 μL feed solution were perfectly separated within 5 h with >400 decontamination factors and >95% yield. In order to evaluate the performance of this system, a reference powdered rock sample was separated using this system. Abundances of objective elements, including 0.23 ng of lutetium, were accurately determined without corrections of chemical recovery yield or subtraction of the process blank. This separation technique saves time and effort for chemical processing, and is useful for ultra-trace quantitative and isotopic analyses of elements in small environmental samples.

Automatic sequential separation with an anion-exchange column for ultra-trace analysis of Pu, U, Th, Pb, and lanthanides in environmental samples

“…If all portion of sample is served to the sequential separation, or the recovery yield is corrected appropriately, more reliable results can be expected. The abundances in a reference sample determined in our previous work [16], 1940 1942 1940 1950 1960 1970 1963 1965 1970 1980 1990 1995 Concentration (ng/g dry wood )…”

“…Pu was eluted with Th in the Th fraction under the conditions used in the previously reported sequential separation [16]. In order to separate Pu and Th, the separation performance of Th and Pu was optimized by varying the chemical composition of the Th eluent as follows: 11 M Table 1.…”

“…The elements of interest were separated using a sequential system called the clean and automatic separation system for ultra-trace analysis (CASSUAL) [16,17]. This system consists of a small anion-exchange column, automatic inert valves, a fraction collector, and Teflon tubes.…”

“…These samples provide reliable chronological information, but it is difficult to determine the ultra-trace Pu contents in these samples because the Pu contents range from sub-pg kg -1 to sub-ng kg -1 . We have successfully developed automatic and sequential separation techniques for U, Th, Pb, and the lanthanides using a single anion-exchange column and mixed media consisting of highly pure acid mixtures of HCl, HNO 3 , CH 3 COOH, and HF [14][15][16][17]. This separation technique eliminates the time and effort required for chemical processing, and is useful for ultra-trace quantitative and isotopic analyses of elements in small and/or low abundance environmental samples.…”

Anion-exchange separation of americium and the lanthanides using a single column

“…In some cases, several tandem columns and/or systematic separation procedures are required to remove other matrix elements 8 . The sequential anion-exchange separation of U, Pu, Th, Pb, and the lanthanides was successfully achieved by using a suitable combination of acetic acid, nitric acid, hydrochloric acid, and the hydrofluoric acid for selective elution of each element in our previous works [9][10][11] . In the current work, elution behavior of Am in this separation system was investigated by separating an 243 Am spike solution.…”