Does Hach offer a probe that can measure pH in oil?

Document ID

Document ID TE928

Published Date

Published Date 27/05/2017
Question
Does Hach offer a probe that can measure pH in oil?
Summary
Measurement of pH in oil
Answer
No Hach pH probes can be used in pure oil. Organic solvents will damage all of Hach’s pH probes. pH is defined as an index of the concentration of hydrogen ion in water or water-based solutions. Since oil is not an ionizing solvent, it has no free hydrogen ions and therefore, it does not have a pH in itself. If the oil contains materials, which when mixed with water (receives hydrogen ions to the water phase), then these will register when the pH of the water phase of the combined solution is measured.
Due to dissociation, pure water has a pH of 7. The hydrogen ion and hydroxide ion are present each at a concentration of 1×10-7. This means that the fraction of each ionized in pure water is 0.0000001 (i.e., 10,000,000 liters of pure water supplies 1 gram-ion of hydrogen). Equivalent amounts of strong acids and strong bases mixed together are neutral at pH 7, and is because they release essentially all (> 90%) of their hydrogen and hydroxide ions when diluted in water and have varying degree of dissociation in non-water liquids.
In summary, one could say that “pH” is a characteristic of a particular oil, but pH is a measure of what is in the water phase only.