Assessment of matrix tolerance for the direct trace elemental analysis in uranium by X-Ray Fluorescence technique using micro focussed beam

Abstract

Determination of trace elemental concentrations in presence of heavy Z matrix like uranium using X-Ray Fluorescence (XRF) based technique requires separation of major matrix from the sample matrix. This separation process is laborious and also produces large amount of organic waste. To counter this problem we have developed a Micro-XRF based technique for the trace elemental analysis in uranium matrix without applying any matrix separation steps. The main challenge of trace elemental analysis in presence of heavy matrix like uranium is severe matrix effect which deteriorates the detection limit as well as the analytical result. In order to assess the matrix tolerance for the direct trace elemental analysis in uranium by X-Ray Fluorescence technique, a detailed study has been conducted to observe the effect of uranium matrix on the analytical results like detection limits or recovery rate etc in the present paper. Based on the detail studies, a limiting concentration for uranium as major matrix has been optimized, up to which matrix effect can be tolerable for trace elemental analysis without further matrix separation. However if the matrix concentration goes beyond that limit, the sample has to be diluted to maintain the uranium matrix concentration below that limit. The presently developed methodology has been validated by determining trace elemental concentration in real natural uranium samples down to few hundred ng/mL concentration level. The methodology reported in this work is simple, cost-effective and less time consuming, with detection limits comparable to other well established trace analytical methods. Moreover it is having an added advantage of avoiding the complex matrix separation steps up to a certain level of matrix concentration.