RAPID-DETERMINATION OF RADIUM ISOTOPES BY ALPHA-SPECTROMETRY

An efficient analytical method for the determination of low-levels of Ra-226 and Ra-224 by alpha spectrometry is described. A cation exchange column was used to separate the analyte from other constituents in the sample (1-50 mL). After preconcentration and separation, the radium was electrodeposited onto a stainless steel disc from a solution of ammonium oxalate and hydrochloric acid. The electrodeposition was accomplished by the addition of platinum in microgram amounts. Linear responses were greater than two orders of magnitude. Detection limits of the procedure. taken as three times the standard deviation of several reagent blank analyses, were (1.8 +/- 0.3) x 10(-4) Bq and (2.9 +/- 0.3) x 10(-4) Bq for Ra-226 and Ra-224, respectively. Recoveries of Ra-226 and Ra-224 ranged from 90% to 100% when samples of drinking water, well water, and dissolved bones were analyzed. Precision was calculated to be less than 5% for the determination of Ra-226. Matrix effects were studied for salts of barium, magnesium, iron, and calcium.