Quantitative phase analysis of commercial ammonium phosphates by PXRD for application in biological systems

Although being an old concern, phosphate analysis is still a tremendous challenge. While many different experimental techniques are found in the literature, very few use powder X-ray diffraction (PXRD) patterns for quantitative phase analysis of different phosphate types. Our measurements performed in four commercial samples of diammonium hydrogen phosphate ((NH 4 ) 2 HPO 4 ) (DAP) show the existence of phosphate contamination mixtures, such as ammonium dihydrogen phosphate (NH 4 H 2 PO 4 ) (ADP). The larger the amount of ADP, the larger the microstrain induced in the DAP phase, which impacts both the aggregation of the nanoparticles in solution and the final anticancer activity of the nanostructure. This study shows that PXRD is an excellent technique for quantitative phase analysis to determine the presence and amount of phosphate contamination in diammonium hydrogen phosphate samples.