A method of obtaining an elemental concentration profile of a sample using x-ray photon spectroscopy measurements is described. Each measurement relates to a different depth in the sample. The sample is shaped to provide access to different depths thereof. Measurements are obtained at respective positions on a bevelled surface exposing material at each of the depths. The method involves fitting the measurements to a mathematical function, dividing the function into a plurality of equal depth wise slices, determining the elemental concentration for the slice corresponding to the thinnest part of the bevel, and then iteratively determining the contribution of each successive slice to the intensity value as being the intensity value measured for that slice minus the intensity value determined to have been contributed by each preceding slice. According to preferred embodiments, a surface correction factor compensating surface effect phenomena is applied to the concentration value calculated for each slice.