The 31 P ssNMR MAS spectra fitting allows the determination of the characteristic CSA parameters (CSA and CSA) of each phosphate species. It was found that ssNMR spectra recorded at pH 12, 10, 4, and 0.5 can predominantly be fitted using a single site corresponding to the following phosphate species: PO4 3-, HPO4 2-, H2PO4 -and H3PO4, respectively (Figure ). As a result, P CSA parameters (CSA and CSA) of these individual phosphate species are extracted (Figure and Table and), and their extracted CSA parameters are in good agreement with their expected symmetries and with experimental values found in sodium or potassium salts. In particular, PO4 3-exhibits a very small CSA magnitude compared to other species, which is in agreement with the high symmetric tetrahedral geometry expected around the phosphorus. We also noticed the small CSA values for HPO4 2-and H3PO4 (0.3-0.4), which are in agreement with their expected C3 symmetry. A characteristic change in sign for CSA from H2PO4 -(negative) to HPO4 2-(positive) was also observed and is in accordance with the literature. Spectra at pH 0.5, 4, 10 and 12 can predominantly be fitted using one single site corresponding to the following phosphate species: PO4 3-, HPO4 2-, H2PO4 -and H3PO4, respectively. Other spectra were fitted by the combination of two individual components. Extracted CSA parameters are listed in Table and SI2.