ASTM D7637-10(2021) PDF

SIGNIFICANCE AND USE 4.1 This test method is based on the cold oxidation of the glycerol by sodium metaperiodate in a strong acidic medium. Formaldehyde and formic acid are produced in this reaction and the latter is used to measure the glycerol content by titration with standard sodium hydroxide solution, to a pH 8.1 ± 0.1. The glycerol content is expressed as a percentage (m/m). 4.2 Interferences—The glycerin sample should be free of organic compounds with more than two hydroxyl groups on adjacent carbon atoms (for example, sugars, glycols). These types of compounds may produce formic acid which interferes with the determination of the glycerol content. SCOPE 1.1 This test method provides the quantitative determination of glycerin by the titrimetric method. It is applicable to all glycerin or glycerin/water mixtures >75 %. 1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard. 1.3 This standard may involve hazardous materials, operations, and equipment. This standard does not purport to address all of the safety concerns associated with its use. It is the responsibility of the user of this standard to consult the established and appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use. Specific precautions are listed in Section 8. 1.4 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.