Eichrom Technology and
Decontamination Steps

Melissa Mannion

Thermo Retec

mmannion@thermoretec.com · (510) 235-2633

This paper describes the discovery of imperfectly decontaminated sample mounts, the confirming research, and the procedure modifications necessary to augment the Eichrom column that had been incorporated into a Strontium purification procedure. Yttrium planchets have been discovered to contain activity decaying on a 1.7-day half-life rather than the 2.7 days of Y-90. It was found that the half-life of contaminants on the planchet mimicked a Strontium/Yttrium (Sr/Y) system closely enough that the contamination was not readily obvious.

Commercial and government laboratories have been using Eichrom resin to improve the productivity, reduce costs and shorten turn-around-times for radioactive analyses. The use of Eichrom resin has increased the efficiency of many procedures, but not all new procedures are successful and some have subsequently required additional modification. Where initial research using Eichrom resins to purify samples may appear successful and a procedure is adopted accordingly, it can be hard to identify problems stemming from the contamination of isotopes in some samples.

In this instance, an Eichrom resin procedure allowed contamination from Barium-140 to be eluted from the column and collected with Strontium on the planchet. Due to the short 13-day half-life of Ba-140, and the ingrowth of its 1.7-day half-life Lanthanum-140 daughter, the Sr counting data mimicked a Sr mount primarily containing Sr-89. The Y-milk appeared to be decaying at about its typical half-life. These characteristics were close enough (within counting statistics) to Sr/Y that they initially escaped detection. Calculated Sr-89/90 values were wrong. Additional steps were added to easily remove the Ba-140 contamination.