Calibration of a chip-based microfluidic calorimeter

The invention provides a calibration method for calibrating a chip-based microfluidic calorimeter (100), wherein the chip-based microfluidic calorimeter (100) comprises one or more thermopiles (110), wherein the calibration method uses the deprotonating reaction of a phosphate group, the method comprising: providing calibration liquids (120) comprising (i) a buffer with a pH range of at least 7-9 and (ii) a first compound with a phosphate group which is protonated in a pH range of at least 3-6, and mixing these calibration liquids (120) in the chip-based microfluidic calorimeter (100) to provide a calibration liquid mixture (123) whereby heat is generated, measuring the heat by the thermopiles (110) and thereby providing a corresponding thermopile signal, and calibrating the chip-based microfluidic calorimeter (100) by relating the thermopile signal to reference data of the deprotonating reaction.