An improved backloading method for better results in quantitative analyses of XRD-data with the Rietveld-method is presented. The quality of the method was checked by single phase structure refinement of orthoclase and also by quantifications of standard mixtures of quartz and orthoclase. The effect of differences in quality of XRD-data by different preparators was investigated. Comparisons of the results show that this method minimizes preferred orientation and improves quantitative precision.