1.1 本试验方法包括用气相色谱法测定环己烷原料中的特定杂质和苯的纯度。 1.2 已发现该试验方法适用于99范围内的苯 % 至100 % 纯度和浓度为2的杂质 mg/kg至10 000毫克/千克。杂质的检测限（LOD）为2 mg/kg，杂质的定量限（LOQ）为6 mg/kg。 1.3 在使用该方法确定试验结果是否符合适用规范时，应根据四舍五入对结果进行四舍五舍五入- 脱离实践方法 第29页 。 1.4 以国际单位制表示的数值应视为标准。本标准中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）。本标准的使用者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。 有关具体危险说明，请参阅 7.2 和截面 8. 。 1.6 本国际标准是根据世界贸易组织技术性贸易壁垒委员会发布的《关于制定国际标准、指南和建议的原则的决定》中确立的国际公认的标准化原则制定的。 ====意义和用途====== 5.1 基于苯中通常存在的杂质，该测试方法可用于苯纯度，并可用于最终产品检查和过程控制。 5.2 该试验方法将检测以下杂质:甲苯、甲基环戊烷、， n -己烷、2-甲基己烷、环己烷、环戊烷、2-甲基戊烷、2,3-二甲基戊烷、3-甲基己烷， n -庚烷、甲基环己烷、乙基环戊烷、2,4-二甲基己烷、三甲基戊烷和其他有特定杂质标准的物质。 如果存在未知杂质，则无法准确测定绝对纯度。

1.1 This test method covers the determination of specific impurities in, and the purity of benzene for cyclohexane feedstock by gas chromatography. 1.2 This test method has been found applicable to benzene in the range from 99 % to 100 % purity and to impurities at concentrations of 2 mg/kg to 10 000 mg/kg. The limit of detection (LOD) is 2 mg/kg for an impurity and the limit of quantitation (LOQ) is 6 mg/kg for an impurity. 1.3 In determining the conformance of the test results using this method to applicable specifications, results shall be rounded off 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. For specific hazard statements, see 7.2 and Section 8 . 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 This test method is useful for benzene purity on the basis of impurities normally present in benzene and may be used for final product inspections and process control. 5.2 This test method will detect the following impurities: toluene, methylcyclopentane, n -hexane, 2-methylhexane, cyclohexane, cyclopentane, 2-methylpentane, 2,3-dimethylpentane, 3-methylhexane, n -heptane, methylcyclohexane, ethylcyclopentane, 2,4-dimethylhexane, trimethylpentane, and others where specific impurity standards are available. Absolute purity cannot be accurately determined if unknown impurities are present.