Automated determination of total acid number (TAN) in new and used lubricating oils and crude oils using the 814 USB Sample Processor. Dissolve oil sample in mixture of toluene and 2-propanol, add paraformaldehyde and titrate with 0.1 mol/L or 0.01 mol/L KOH in propan-2-ol. The endpoint is indicated by an endothermic response caused by the base-catalyzed depolymerization of paraformaldehyde.

Reference: 1. M. J. D. Carneiro, M. A. Feres Júnior, and O. E. S. Godinho. Determination of the acidity of oils using paraformaldehyde as a thermometric end-point indicator. J. Braz. Chem. Soc. 13 (5) 692-694 (2002)

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Metrohm AG

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