X-ray fluorescence analysis is widely used in field survey and laboratory analysis.Background of a characteristic X-ray peak must be subtracted for determining the elemental content.In this paper

the method of Fourier transform background subtraction is used.It is less affected by changes in the background than linear background subtraction.The result shows that using FFT background subtraction of XRF spectra collected in a field survey

the Sr contents are 11.0% less in average than those obtained in laboratory XRF analysis of the samples

whereas using linear background subtraction

the average error is –25.9%.