AN ASSESSMENT OF THE SELECTION CRITERIA FOR AN ANALYTICAL METHOD FOR RA-226 IN ENVIRONMENTAL-SAMPLES

This paper examines the process of making a decision on the optimum te chnique for the measurement of low concentrations of Ra-226 in environ mental materials. The available counting techniques are alpha spectrom etry, high resolution gamma spectrometry and liquid scintillation coun ting. The properties of the analytical technique; sensitivity, lower l imit of detection (LLD) and precision are considered. Method selection is also restricted by the available sample size and activity. The inf luence of procedure backgrounds, geometric efficiency, chemical recove ry, counting time, sample size and activity on the precision and LLD a re investigated. The process of method selection, applicable to a wide range of samples, is illustrated by reference to sediments, waters an d tissues.