Chemistry
Coulometric Titration for Trace Chloride Determination in Water
Quick fact
Coulometric titration can measure chloride down to the microgram level, and it's often used as a reference method because it doesn't rely on preparing dilute standard solutions, which are prone to error.
Why this is interesting
You probably know that chloride is a natural component of water, but how can we measure it when it's present in only a few parts per million? A surprising electrochemical trick uses the current you pass through the sample to count the chloride ions themselves.