- Density: ~ 1,00 g/cm3 r- Solub. in water: (20 ºC): miscibler- Tariff number: 3822 00 00 00r- 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.rrSPECIFICATIONSrpH at 20 ºC: 13,00 ± 0,02runcertainty ± 0,01 Composition per litre is 3,7 g Potassium chloride and 4,3 g Sodium hydroxide. rrStandard 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. r0: 13,80r5: 13,59r10: 13,37r15: 13,18r20: 13,00r25: 12,83r30: 12,67r35: 12,59r40: 12,41r45: 12,28r50: 12,15r