The reaction of protonation of 2-amino-2-(hydroxymethyl)-1,3-propanediol (TRIS) is a suitable one for the calibration of isothermal titration calorimeter (ITC), providing that experimental conditions are appropriately chosen. The conditions and methods for handling experimental data from a nanowatt-ITC are discussed. Also, the binding of Ba2+ to 18-Crown-6 is successfully used to check the accuracy and precision of the chemical calibration performed with TRIS. This latter reaction has the additional advantage that the data can also be used for a check on the determination of the value of a binding constant. The anomaly of the first injection in ITC is analyzed and, by combining calorimetric and spectroscopic measurements, it is shown that it mainly results from a backlash effect of the syringe plunger rather than from a diffusion effect.

The TRIS reaction is suitable for calibrating isothermal titration calorimeters, with proper experimental conditions and data handling methods.

Conditions for calibration of an isothermal titration calorimeter using chemical reactions

Key Takeaway: The TRIS reaction is suitable for calibrating isothermal titration calorimeters, with proper experimental conditions and data handling methods.