Thermometric titration of acid number
White Paper

Thermometric Titration of Acid Number according to ASTM D8045

White Paper

The new Thermotrode™ accurately determines the Acid Number of a wide range of petrochemical products with a fast and straightforward method, which is fully compliant to the ASTM D8045 standard.

Acid number (AN) determination, a common analysis in the oil industry, is used to monitor oil degradation and acidity. It helps prevent machine breakdowns and pipeline leakage due to corrosive acidic oil. Although standard potentiometric acid-base titrations work well for the determination of AN, they can be time consuming measurements.

The pH electrode needs to be precisely calibrated and conditioned, and the titration endpoint is not always easily found. One approach to avoid such pitfalls is to measure the temperature change that occurs during a catalyzed titration. This catalyzed thermometric titration, described in the ASTM D8045 standard (1), is faster, needs less sensor maintenance, and is as precise and reliable as the standard determination of AN, according to the ASTM D664 standard

Based on the standard ASTM D8045, this White Paper explains in detail the procedure and the advantages of this new method. You will learn more about:

  • Thermometric Acid Number Titration: Principle
  • Blank and Titer Measurement
  • Sample Measurement
  • Thermometric vs. Potentiometric Titration of AN
Download the White Paper and learn from METTLER TOLEDO’s expertise in thermometric titration. The new Thermotrode sensor allows precise acid number determination of a wide range of petrochemical products with a fast and simple method


  1. Thermometric Acid Number Titration: Principle
  2. Blank and Titer Measurement
  3. Sample Measurement
  4. Thermometric vs. Potentiometric Titration of AN
  5. METTLER TOLEDO Solution
  6. Conclusion
  7. References
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