You searched for: “aquametry
aquametry (s) (noun)
Analytical procedures; such as, oven drying, distillation, or Karl Fischer titration, used to measure the quantity of water present in materials.

A measured amount of a solution of unknown concentration is added to a known volume of a second solution until the reaction between them is complete; the concentration of the unknown solution (the titer) can them be calculated.

A Karl Flischer technique is the titration of a sample with a solution of iodine, pyridine, methanol, and sulfur dioxide which are used to determine trace quantities of water in a sample. The end point is indicated by yellowish color change.