Wave number (cm-1) Frequency Assignment Control Treated 2975 3357 O-H stretching  due to water of crystallization 2826-2871 2914-3111 PO-H asymmetrical stretching 2359 2350 PO-H symmetrical stretching 1717-1760 1701-1717 O=P-OH deformation vibration 1159-1356 1132-1260 P=O stretching 1075 1057 P-O stretching 949 953 PO-H bending 548 540 Out of plane P-OH bending

Table 1: FT-IR vibrational peaks observed in disodium hydrogen orthophosphate.