Mass attenuation coefficient corrections, for Rietveld phase analysis with an external compositional calibration standard, may be made using Compton scattering intensities measured by X-ray fluorescence spectrometry. The method is mainly useful for Rietveld phase analysis when mixing an internal standard is impossible or undesirable. The validity of the method has been demonstrated using a suite of alumina-zirconia powders of known composition. Also presented are results for a typical application—determination of phase composition depth profiles defining the graded compositional character of an aluminium titanate/zirconia-alumina ceramic composite.