- Density: ~ 1,01 g/cm3 - Solub. in water: (20 ºC): miscible - Tariff number: 3822 00 00 00 - Applications: This reference material is intended for the calibration of pH meters and electrodes used for pH measurement or as a control sample for measuring the pH value. SPECIFICATIONS pH at 20 ºC: 12,00 specification range: 11,98 - 12,02 uncertainty : ± 0,01 Composition per litre is 10,6 g di-Sodium hydrogen phosphate and 3,10 g Sodium hydroxide. Standard buffer solutions are prepared using gravimetric and volumetric procedures. The batch value is determined by measurement with a combination glass electrode against two-point calibration according to DIN 19268. This pH buffer solution is traceable to Standard Reference Material from NIST. 0: 12,58 5: 12,41 10: 12,26 15: 12,10 20: 12,00 25: 11,88 30: 11,72 35: 11,67 40: 11,54 45: 11,41 50: 11,33