Method Validation and Measurement Uncertainty Evaluation of the Radiochemical Procedure for the Determination of 231Pa in Siliceous Cake by Gamma Spectrometry

Abstract An in-house radiochemical procedure for the separation of 231Pa from siliceous cake - a waste stream of monazite processing plant, followed by its determination using gamma ray spectrometry, has been developed in our laboratory. Evaluation of reliability of analytical results of the radiochemical procedure is important for validating the fitness of purpose of an analytical method. The present paper describes the statistical evaluation of the analytical results obtained, by estimating the overall uncertainty in the measurement process. The bottom-up approach, also called as ISO approach (ISO/IEC guide 98-3:2008), was adopted to evaluate the overall uncertainty in which the individual sources were identified, evaluated and propagated. The major contribution to the combined uncertainty in measurement of 231Pa was from efficiency calibration. Besides this, counting statistics in the sample and chemical yield of the process incorporated significant contribution to combined uncertainty. The precision of the results obtained was found to be acceptable, as ascertained by the Horwitz Ratio, for the performance of a single laboratory. GRAPHICAL ABSTRACT