Sample area dependence in quantitative EDXRF analysis

The measurement of small, thin samples with an area of the order of mm 2 with the ordinary EDXRF technique requires that special care be taken to include the sample size in the evaluation of element concentrations. Results are reported obtained using a standard procedure for the evalution of small samples used in the author's laboratory. This procedure makes use of an input parameter, viz. a ‘geometrical factor’ corresponding to the sample area which is used in the evaluation software. The results show that an almost straight line can be fitted to describe the parameter as a function of sample area for small samples (with an area of the order of mm 2 ), but that the corrections for inhomogeneity of the beam intensity are needed in many cases. For large samples (with an area of the order of cm 2 ) the parameter is equal to unity.