【国外标准】 Standard Test Method for Determination of Hydroquinone (HQ) Content in Vinyl Acetate Monomer (VAM) Using Ultraviolet-Visible (UV-Vis) Spectrophotometer

4.1 VAM is an organic vinyl ester compound. This colorless liquid is the precursor to polyvinyl acetate, an important industrial polymer. VAM may be subject to rapid spontaneous polymerization if the inhibitor is not present or becomes depleted during prolonged storage.4.2 VAM is typically shipped with a HQ inhibitor as free radical scavenger. VAM should be evaluated to ensure that appropriate systems (for example, temperature and inhibitor quantity) are assured during storage, transportation, and getting prolonged shelf life.4.3 Most VAM shipped from the manufacturer will contain an inhibitor, typically 3 to 5 ppm HQ for regional shipments and up to 25 ppm HQ for long-range shipments.1.1 This test method covers the determination of hydroquinone (HQ) in colorless vinyl acetate monomer (VAM). This test method is applicable to the determination of HQ in the concentration range from 1 to 25 ppm.1.2 For purposes of determining conformance of an observed or a calculated value using this test method to relevant specifications, test result(s) shall be rounded off “to the nearest unit” in the last right-hand digit used in expressing the specification limit in accordance with Practice E29.1.3 For ensuring safety, hazard information and guidance, follow the manufacturer’s material safety data sheet.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.