pH 4.01 Buffer Preparation.
1. – Accurately weigh out 8.954 g of Disodium hydrogen phosphate (Na2HPO4.12H2O) and 3.4023 g of potassium dihydrogen phosphate (KH2PO4).
2. – Dissolve both the above in distilled water and make up to 1L in a 1L volumetric flask. .