Hello Riley_5000,
Unfortunately, there is a very high chance that there is little to no correlation based on a pure pH measurement. The solubility and retention of Ammonia greatly depends on temperature, concentration of ammonia in the air phase, types of contaminants in the water (salts, emulsifiers, treating chemistry, corrosion products etc.). Agitation also is a factor (more agitation causes more ammonia to be removed from the solution).
I wish you the best with your calculation.
Sincerely,
Eugene