The certified secondary standard reference buffer solution (potassium dihydrogen phosphate/disodium hydrogen phosphate) is gravimetrically prepared using high-quality reagents in high-purity water. Its pH value is measured by differential potentiometry with two platinum hydrogen electrodes against primary certified reference materials from NIST & PTB.

The buffer solution can be used to calibrate, qualify, and monitor pH measuring instruments and as a control for testing other buffer solutions.

pH-value: 6.861 - 6.867