Development of a certified reference material for calibration of DSC and DTA below room temperature: NMIJ CRM 5401-a, Cyclohexane for Thermal Analysis

• We developed a new CRM for quality assurance of DSC and DTA below room temperature.
• Certified values are temperatures and enthalpies of two phase transitions.
• Certified values agree with literature values.
• Certified values are determined by adiabatic calorimetry and traceable to the SI.
• Purity of this CRM was confirmed more than 0.9999.

For the quality assurance of performance of differential scanning calorimeters (DSC) and differential thermal analyzers (DTA) below room temperature, we have developed “NMIJ CRM 5401-a, Cyclohexane for Thermal Analysis” applicable to calibration of DSC and DTA in the low temperature. Adiabatic calorimetry was used to measure the temperatures and enthalpies of solid–solid phase transition and fusion as certified values, and to determine the purity in amount of substance fraction as information. The certified values are consistent with their corresponding literature values within expanded uncertainties and have traceability to the SI. Purity in amount of substance fraction was measured by fractional melting method based on freezing point depression method and was confirmed to be more than 0.9999. NMIJ CRM 5401-a was produced based on a quality system in compliance with ISO Guide 34: 2000. We demonstrate the usefulness of NMIJ CRM 5401-a in the calibration, quality control, and validation aspects of DSC and DTA