Calibration of nanowatt isothermal titration calorimeters with overflow reaction vessels.

Obtaining accurate results with nanowatt titration calorimeters with overflow cells requires mass calibration of the buret injection volume, chemical calibration of the reaction vessel effective volume, and chemical calibration of the calorimetric factor used to convert the measured electrical signal to heat rate. Potential errors in electrical calibration of power compensation calorimeters require validation of the calorimetric factor with chemical reactions with accurately known stoichiometries and enthalpy changes. The effective volume of the reaction vessel can be determined from the endpoint of a quantitative reaction with known stoichiometries. Methods for calibration and potential calibration errors to be avoided are described. Publication of results obtained must include data on calibrations and sufficient raw data to assess precision and accuracy of the results.