Metrological Support for Titration Isothermal Calorimetry: Prospects for the Development of Certified Reference Materials

Isothermal titration calorimetry is used to study the thermal effects of chemical and physicochemical processes. The wide application of this method has revealed a number of problems. Among them is insufficient metrological support for isothermal titration calorimeters, which leads to inconsistency of the results obtained using different models of calorimeters. The electrical and chemical procedures currently used for calibrating calorimeters have several limitations. This work aims to develop an approach to creating certified reference materials (CRMs) for the unit of heat quantity of physical and chemical interactions having metrological traceability to the main SI units. An analysis of the state of metrological support in isothermal titration calorimetry measurements was carried out. The basic requirements for CRM candidate substances were formulated. The target uncertainty of the integral heat of dilution of propan-1-ol solutions was estimated by analyzing the characteristics of measuring instruments, which allowed the requirements for the measurement method used to characterize CRMs to be specified. A method for determining the certified value of integral heat of dilution traceable to the GET 133 State Primary Special Standard of the unit of heat quantity in the field of solution and reaction calorimetry was proposed.