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A new Standard Reference Material® (SRM®), designated SRM 2232a, has been certified for the temperature and enthalpy calibration of differential scanning calorimeters (DSCs). This is a replacement for the previously sold out version, SRM 2232. SRM 2232a was sourced from a single lot of high-purity ( 99.99999% metals basis, by weight) indium. The melting point of SRM 2232a has been certified to be equal to (156.5985 ± 0.00032) °C using a fixed-point cell and direct comparisons with the NIST laboratory reference cell that constitutes NIST's primary realization of the indium freezing point. The enthalpy of fusion of SRM 2232a has been certified to be equal to (28.58 ± 0.17) J·g-1 via DSC measurements using an instrument calibrated with certified reference materials obtained from another national metrology institute. This document provides all relevant measurement and analysis details for the certification of SRM 2232a.
Fortin, T.
, Herman, T.
, Koepke, A.
and Splett, J.
(2024),
Certification of Standard Reference Material® 2232a: Indium for DSC Temperature and Enthalpy Calibration, Special Publication (NIST SP), National Institute of Standards and Technology, Gaithersburg, MD, [online], https://doi.org/10.6028/NIST.SP.260-242, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=956617
(Accessed October 6, 2025)