1.1 本试验方法包括使用离子选择电极在线测定水中痕量钠。 1.2 本试验方法基于技术文献中报告的钠离子电极的在线应用 ( 1- 3. ) . 2. 它通常适用于0.01到10的范围 000微克/升。 1.3 分析员应意识到，根据实践需要，为精度和偏差陈述提供足够的协作数据 D2777 未提供。参见第节 16 详细信息。 1.4 以国际单位制表示的数值应视为标准值。国际单位制后括号中给出的值仅供参考，不被视为标准值。 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。 有关具体的危险说明，请参阅第节 6. . 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 钠是一种普遍存在的污染物，是第一个突破去离子设备的阳离子。该测试方法允许以微克/升（十亿分之一）的浓度测量低钠水中的钠，以识别污染或监测设备性能。应用包括监控补给系统、冷凝器、冷凝水抛光器、给水、锅炉水和蒸汽。 4.2 与高纯度样品的电导率测量相比，该测试方法更为敏感和选择性。

1.1 This test method covers the on-line determination of trace amounts of sodium in water using an ion-selective electrode. 1.2 This test method is based on on-line application of the sodium ion electrode as reported in the technical literature ( 1- 3 ) . 2 It is generally applicable over the range of 0.01 to 10 000 μg/L. 1.3 The analyst should be aware that adequate collaborative data for precision and bias statements as required by Practice D2777 are not provided. See Section 16 for details. 1.4 The values stated in SI units are to be regarded as standard. The values given in parentheses after SI units are provided for information only and are not considered 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 Section 6 . 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 Sodium is a pervasive contaminant and it is the first cation to break through deionization equipment. This test method allows measuring sodium in low-sodium waters at micrograms per litre (parts per billion) concentrations to identify contamination or to monitor equipment performance. Applications include monitoring makeup systems, condensers, condensate polishers, feedwater, boilerwater, and steam. 4.2 This test method is more sensitive and selective than conductivity measurements on high purity samples.