This paper describes the determination of aluminum in the presence of silica using a method based on X-ray scattering spectrometry coupled with chemometric tools (principal component analysis and partial least squares) that treat samples according to their Al concentrations.Samples were prepared by mixing Al and Si oxides. X-ray spectra of all samples, including pure oxides of aluminum and silicon, were submitted to the chemometric tools. Principal component analysis results show that it is possible to classify three subgroups of Al (low, medium and high Al content), whereas partial least squares 1 was used to construct calibration and cross-validation models for Al in the presence of Si.The method is simple, fast, does not require sample dissolution prior to analysis, is of low cost and can be applied as a routine procedure. The method was used to quantify Al in some chromatographic stationary phases covered with a layer of Al 2 O 3 . Good correlations with low errors were obtained.