859 Titrotherm

Importance of the Topic

The measurement of reaction enthalpy through thermometric titration offers a universal and robust alternative to potentiometric methods. It circumvents issues related to electrode availability, calibration requirements, and interference by aggressive or complex sample matrices, enhancing reliability in routine QA/QC, research and industrial applications.

Objectives and Article Overview

This application note presents the Metrohm 859 Titrotherm and demonstrates how thermometric titration complements potentiometry. It covers the underlying principles, key advantages, instrumental features, software integration, and practical examples including direct sodium analysis in foods, multiacid determinations and catalytic endpoint enhancement.

Methodology and Principles

Thermometric titration tracks exothermic or endothermic temperature changes as titrant reacts with the analyte. The approach is based on ΔH = ΔG + TΔS, and endpoints are determined by analyzing the first and second derivatives of the temperature curve against titrant volume.

Used Instrumentation

• 859 Titrotherm USB-enabled thermometric titrator
• Thermoprobe thermistor sensor (0.3 s response, 10⁻⁵ K resolution)
• Dosino Dosing Units (2–50 mL) with integrated drive motors
• Rod stirrer and titration stand
• tiamo software for method control and reporting
• Optional 814 USB Sample Processor and 815 Robotic USB Sample Processor XL

Main Results and Discussion

• Calibration-free, maintenance-free sensor operation with rapid response
• Automation capabilities for unattended high-throughput analyses
• Direct sodium determination in ketchup via exothermic NaK₂AlF₆ formation
• Clear resolution of three-point titration endpoints in phosphoric/nitric acid mixtures
• Catalytically enhanced detection of weak enthalpy reactions using paraformaldehyde

Benefits and Practical Applications

• Single, universal sensor for diverse titrations
• No membrane or reference electrode complications
• Compatibility with aggressive and viscous samples
• Accelerated result generation for improved laboratory efficiency
• Reduced operational costs by eliminating sensor calibration

Future Trends and Opportunities

Advances in sensor miniaturization and software analytics may enable inline process monitoring and microfluidic integration. Machine learning-driven endpoint detection and method optimization could broaden applicability in environmental, pharmaceutical and industrial QA/QC contexts.

Conclusion

The Metrohm 859 Titrotherm delivers a versatile, reliable, and user-friendly thermometric titration solution. By leveraging enthalpy changes, it addresses key limitations of potentiometry, offering maintenance-free operation, universal applicability and efficient automation for modern analytical laboratories.

Reference

Metrohm Application Note 859 Titrotherm, Metrohm Ltd., Herisau, Switzerland (2012)