1.1 本试验方法旨在测定丁二烯、异戊二烯和苯乙烯中氮氧自由基4-羟基-2,2,6,6-四甲基哌啶-1-氧基（H-Tempo）的含量。 1.2 本试验方法适用于氮氧自由基4-羟基-2,2,6,6-四甲基哌啶-1-氧基（H-Tempo）浓度为100 mg/kg的样品。氮氧自由基4-羟基-2,2,6,6-四甲基哌啶-1-氧基（H-Tempo）的检测限（LOD）为0.47 mg/kg，定量限（LOQ）为1.6 mg/kg氮氧自由基4-羟基-2,2,6,6-四甲基哌啶-1-氧基（H-Tempo）。 1.3 以下内容适用于确定使用本试验方法的试验结果是否符合适用规范，结果应根据四舍五入进行四舍五入- 非实践方法 E29年 . 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====== 4.1 氮氧自由基（H-Tempo、O-Tempo（4-oxo-2,2,6,6-四甲基哌啶-1-氧基）等）广泛用作单体（异戊二烯、丁二烯、苯乙烯等）运输、储存和分离过程中的热聚合抑制剂。本试验方法提供了测定单体中氮氧自由基的程序。 4.2 该程序可用于测定其他溶剂（二甲基甲酰胺、二甲基亚砜等）中氮氧自由基（H-Tempo、O-Tempo等）的含量。

1.1 This test method is designed to determine the content of nitroxide radical 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl (H-Tempo) in butadiene, isoprene, and styrene. 1.2 This test method is applicable to samples with nitroxide radical 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl (H-Tempo) with concentrations to 100 mg⁄kg. The limit of detection (LOD) is 0.47 mg/kg for nitroxide radical 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl (H-Tempo) and the limit of quantitation (LOQ) is 1.6 mg/kg nitroxide radical 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl (H-Tempo). 1.3 The following applies for the purposes of determining the conformance of the test results using this test method to applicable specifications, results shall be rounded of in accordance with the rounding-off method of Practice E29 . 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 ====== 4.1 Nitroxide radicals (H-Tempo, O-Tempo (4-oxo-2,2,6,6-tetramethylpiperidine-1-oxyl), etc.) are widely used as inhibitors of thermopolymerization in the processes of transportation, storage, and separation of monomers (isoprene, butadiene, styrene, etc.). This test method provides a procedure for assaying nitroxide radicals in monomers. 4.2 This procedure can be used for determination of the content of nitroxide radicals (H-Tempo, O-Tempo, etc.) in other solvents (dimethyl formamide, DMSO etc.).