【国外标准】 Standard Test Method for Relative Initial and Final Melting Points and the Melting Range of Organic Chemicals

5.1 It has long been recognized that narrow melting range and high final melting point are good indications of high purity in crystalline organic compounds. Several ASTM test methods use these criteria to assay the purity of organic compounds (Note 1).NOTE 1: Other ASTM test methods using melting (or freezing point) data to indicate sample purity are Test Methods D852 and D6875.5.2 The relatively simple and rapid test prescribed in this test method shows the sample under test to be either more or less pure than the standard sample. For specification purposes, a minimum allowable purity can be assured by setting limits on the differences in final melting points and the melting ranges between the standard sample and the sample under test.1.1 This test method covers the determination, by a capillary tube method, of the initial melting point and the final melting point, which define the melting range, of samples of organic chemicals whose melting points without decomposition fall between 30 °C and 250 °C.1.2 This test method is applicable only to crystalline materials that are sufficiently stable in storage to met the requirements of a satisfactory standard sample as defined in Section 7.1.3 This test method is not directly applicable to opaque materials or to noncrystalline materials such as waxes, fats, and fatty acids.1.4 Review the current Safety Data Sheets (SDS) for detailed information concerning toxicity, first aid procedures, handling, and safety precautions.1.5 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.1.6 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.1.7 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.