IMPROVED TECHNIQUE FOR QUANTITATIVE EDXRF ANALYSIS OF POWDERED PLANT-SAMPLES

An improved technique for energy-dispersive x-ray fluorescence analysi s of powdered plant samples is presented. It is based on the use of a special rotating and moveable sample holder (RMSH), This sample holder provides both controlled rotation and lateral transfer movements of t he sample while a measurement is carried out, consequently simulating homogeneous excitation conditions over the sample. In this way it comp ensates for effects caused by the typical inhomogeneous distribution o f intensity within the x-ray beam exciting the elements in the sample. The sample consists of powdered dry plant material deposited in an ea sy way on an adhesive tape, providing a stable layer of plant particle s covering the surface. The mean size of the particles fixed on the ta pe results in a thin or intermediate thickness sample, 0.8-2.5 mg cm(- 2). The application of RMSH provides an easy sample preparation method and improved performance, lowering the detection limits of the measur ements and resulting in reproducible, reliable and consistent data, (C ) 1998 John Wiley & Sons, Ltd.