Titration accuracy/resolution question

I’ve just starting using the LaMotte BrewLab and am wondering about how to interpret titration test results. In essence if “1 drop =10 ppm” and “2 drops = 20 ppm”, and 1 drop results in no change in color but the 2nd drop results in a full change in color, what is the concentration?

My guess is that it could be anywhere from 11-20 ppm.

I prepared rough graphs to illustrate (I don’t know how closely they would resemble a real titration curve).

For high concentrations a difference of 10 ppm wouldn’t matter much…it is the lower concentrations I am concerned with, since for small concentrations, things like sulfate/chloride ratios can vary widely.

I believe in a titration test the color change is an end point calculation so 2 drops = 20ppm. You say 10ppm wouldn’t matter so 20ppm is fine. If you need to be more accurate you have to increase your solution. W
hat are you measuring?

The test kit has titrations for total hardness, calcium hardness, total alkalinity, and chloride concentration. Magnesium and sodium are based on those tests, and sulfates ae measured via turbidity.