By Dianne Hermance
Updated Mar 24, 2022
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In the pharmaceutical industry, the purity of a compound can be the difference between therapeutic success and failure. Potentiometric titration is a proven technique that enables chemists to verify purity with unmatched accuracy by monitoring the electrical potential change as a titrant reacts with an analyte.
Potentiometric titration measures voltage changes during a titration, offering a cost‑effective, precise, and automated method for determining sample purity—ideal for pharmaceuticals and other high‑purity fields.
Solid samples are weighed and dissolved in a solvent. A standardized titrant, stored in a burette, is introduced into the test vessel. The titrant passes first through a reference electrode and then an indicator electrode (or a combined electrode). The potential difference, recorded in millivolts, is plotted against the volume of titrant added. The resulting sigmoid curve shows a steep slope at the equivalence point. The endpoint is identified either manually with concentric arc templates or automatically by software that detects the rapid change in slope.
Typical lower concentration limits are around 10-4 M. Modern software minimizes measurement error, providing results with three‑digit milliliter precision.
Unlike traditional indicator‑based methods, potentiometric titration requires no visual endpoint—reducing subjectivity and increasing reproducibility. It accommodates various titration types, including acid–base, redox, precipitation, and complexometric analyses.
Key advantages include:
These features make potentiometric titration a reliable, scalable choice for laboratories prioritizing purity verification.
