1.1 本试验方法描述了使用差示扫描量热法和范特霍夫方程测定纯度大于98.5摩尔%的材料纯度。 1.2 本试验方法适用于具有明确熔融温度的热稳定化合物。 1.3 通过本试验方法测定纯度仅适用于杂质溶解在熔体中且不溶于晶体的情况。 1.4 以国际单位制表示的数值应视为标准值。本标准不包括其他计量单位。 1.5 本标准并非旨在解决与其使用相关的所有安全问题（如有）。 本标准的用户有责任在使用前制定适当的安全、健康和环境实践，并确定监管限制的适用性。 1.6 本国际标准是根据世界贸易组织技术性贸易壁垒（TBT）委员会发布的《关于制定国际标准、指南和建议的原则的决定》中确立的国际公认标准化原则制定的。 ====意义和用途====== 5.1 随着杂质含量的增加，化合物的熔化温度范围变宽。 这一现象可用熔点下降的范特霍夫方程近似描述。在这种熔化过程中，测量和记录进入试样的瞬时热流作为温度的函数，是生成适合于通过范特霍夫方程进行分析的数据的一种实用方法。 5.2 获得的结果包括:样品纯度（以摩尔百分比表示）；熔化焓（以J/mol表示）；以及主要成分纯形式的熔化温度（以开尔文表示）。 5.3 通常，该试验方法的重复性随着纯度水平的降低而降低。 当混合物主要成分的纯度水平低于98.5 mol时，通常认为该试验方法不可靠 % 或者当增量焓校正( c )超过20 % 原始探测到的聚变焓。 5.4 该测试方法用于质量控制、规范验收和研究。

1.1 This test method describes the determination of purity of materials greater than 98.5 mole percent purity using differential scanning calorimetry and the van’t Hoff equation. 1.2 This test method is applicable to thermally stable compounds with well-defined melting temperatures. 1.3 Determination of purity by this test method is only applicable when the impurity dissolves in the melt and is insoluble in the crystal. 1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard. 1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use. 1.6 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee. ====== Significance And Use ====== 5.1 The melting temperature range of a compound broadens as the impurity level rises. This phenomenon is described approximately by the van’t Hoff equation for melting point depressions. Measuring and recording the instantaneous heat flow into the specimen as a function of temperature during such a melting process is a practical way for the generation of data suitable for analysis by the van’t Hoff equation. 5.2 The results obtained include: sample purity (expressed as mole percent); enthalpy of fusion (expressed as J/mol); and the melting temperature (expressed in Kelvin) of the pure form of the major component. 5.3 Generally, the repeatability of this test method decreases as the purity level decreases. This test method is ordinarily considered unreliable when the purity level of the major component of the mixture is less than 98.5 mol % or when the incremental enthalpy correction ( c ) exceeds 20 % of the original detected enthalpy of fusion. 5.4 This test method is used for quality control, specification acceptance, and research.