Radiometric determination of 210Pb in powder samples by the method of standard additions

The method of standard additions is a well known procedure in chemistry for the measurement of trace substances. The use of this method is described in the radiometric determination of ²¹⁰Pb activity via the γ-ray at 46.5 keV emitted in about 4% of the decays. Standard additions of ²¹⁰Pb activity are adsorbed on anion exchange resin which is then mixed with the sample. The procedure used to extract the area of the photopeak from the continuum on which it is superimposed, is described in detail. The value of the ²¹⁰Pb activity is calculated using the slope and intercept of the best straight line fitting the count-rate data plotted against added activity. Results obtained on four standard ore samples indicate that this method yields results of comparable accuracy to other methods such as β-ray spectrometry of the prompt ²¹⁰Bi daughter. This method, however, avoids the tedious chemical separations required.