1.1 本试验方法 2. 包括4-羧基苯甲醛（4-CBA）和 p -甲苯甲酸( p -通过弱阴离子交换高效液相色谱法（HPLC）测定精对苯二甲酸（PTA）中的TOL）。该方法适用于2至500 mg/kg的4-CBA和 p -TOL分别为10至500 mg/kg。 1.2 在使用该方法确定测试结果是否符合适用规范时，应根据修约方法对结果进行修约 E29年 . 1.3 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。 1.4 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。 1.5 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 4-CBA和 p -用于生产聚酯的PTA中的TOL是不可取的，因为它们可以减缓聚合过程，并且4-CBA也由于热不稳定性使聚合物着色。 4.2 确定4-CBA和 p -通常需要PTA制造过程中剩余的TOL。该测试方法适用于设定规格，并可作为生产或使用这些产品的内部质量控制工具。

1.1 This test method 2 covers the determination of the 4-Carboxybenzaldehyde (4-CBA) and p -Toluic acid ( p -TOL) in purified terephthalic acid (PTA) by weak anion exchange high performance liquid chromatography (HPLC). This method is applicable for 4-CBA from 2 to 500 mg/kg and for p -TOL from 10 to 500 mg/kg, respectively. 1.2 In determining the conformance of the test results using this method to applicable specification, results shall be rounded off in accordance with the rounding-off method of Practice E29 . 1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard. 1.4 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. 1.5 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 The presence of 4-CBA and p -TOL in PTA used for the production of polyester is undesirable because they can slow down the polymerization process, and 4-CBA is also imparting coloration to the polymer due to thermal instability. 4.2 Determining the amount of 4-CBA and p -TOL remaining from the manufacture of PTA is often required. This test method is suitable for setting specifications and could be used as an internal quality control tool where these products are produced or are used.