AN-H-073
Total acid number in biodiesel with thermometric titration
Summary
Biodiesel degrades over time, forming acidic compounds that can lead to corrosion of automative parts. Therefore, ASTM D6751 and EN 14214 stipulate a maximum acid number of 0.5 mg KOH/g for biodiesel. Thermometric titration is a fast and accurate method for determining TAN (total acid number) values in biodiesel, without the need for sensor reconditioning.
This Application Note describes the procedure and conditions for performing thermometric titration of biodiesel with acid numbers as low as 0.05 mg KOH/g sample. The biodiesel is dissolved in isopropanol and then titrated using 0.01 mol/L KOH. Paraformaldehyde is used as indicator for the endpoint.