Purification of pivalic acid : its evaluation as a temperature standard reference material

The suitability of pivalic acid was confirmed as a secondary temperature standard material. Triple-point cells of pivalic acid were obtained by using combined process of vacuum distillation with zone refining. A detailed description of the purification process was given. The melting curves were used as criteria for determination of purities of pivalic acid. Triple points of these cells with purity of 99.9997% were measured to be by using the melting plateau curves. Thus the triple point cells of pivalic acid appear to be able to use for the calibration of thermistor thermometers with moderate precision.