Radiochemical separation of Cd-109 and Hg-203 by ion exchange chromatography

Abstract

NAA of mercury and cadmium in food, at trace levels, usually needs suitable methods of radiochemical separation. This work explores two of such procedures. In the firs procedure and irradiated sample is heated with a mixture of sulphuric, nitric and perchloric acid under reflux conditions in presence of potassium dichromate. Mercury is isolated by retention in a small column of granulated copper, the cadmium from the sample is deposited in a strongly acid cation exchange column and eluted with 0.75 N HCl. In the second procedure the sample is heated in a Kjeldahl flask, with a mixture of sulphuric and nitric acids with periodical addition of hydrogen peroxide. The cadmium and mercury are retained in a cation exchange column and separated by selective elution. Percentage of recovery, through sample dissolution and radiochemical separation, was determined by gamma spectrometry of radiotracers as well as by EDITA titrimetry of the carriers. Tracer experiments employing Cd (109) and Hg (203), show appropriated recoveries, enabling these separations useful for NAA of such elements at trace level.