1.1 本试验方法规定了用玻璃电极电测水溶液pH值的仪器和程序。它不涉及溶液的制备方式。可以在含有高浓度电解质或水溶性有机化合物或两者的水溶液中进行高精度的pH测量。然而，应该理解的是，在这种溶液中的pH测量仅仅是氢离子浓度或活性的半定量指示。 只有当介质的组成与标准参考溶液的组成大致匹配时，测量的pH才会对这些量产生准确的结果。一般来说，除非pH值在2和12之间，并且电解质和非电解质的浓度都不超过0.1mol/L（M），否则该测试方法将无法准确测量氢离子活性。 1.2 以国际单位制表示的数值应视为标准。括号中的值仅供参考。 1.3 在使用该方法确定试验结果是否符合适用规范的情况下，应根据四舍五入对结果进行四舍五舍五入- 偏离练习方法 E29 . 1.4 本标准并不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。 1.5 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====== 4.1 pH值在 1.1 ，是氢离子浓度的精确测量，因此广泛用于水溶液的表征。 4.2 pH测量是化学工业的主要过程控制变量之一，在污染控制中占有突出地位。

1.1 This test method specifies the apparatus and procedures for the electrometric measurement of pH values of aqueous solutions with the glass electrode. It does not deal with the manner in which the solutions are prepared. pH measurements of good precision can be made in aqueous solutions containing high concentrations of electrolytes or water-soluble organic compounds, or both. It should be understood, however, that pH measurements in such solutions are only a semiquantitative indication of hydrogen ion concentration or activity. The measured pH will yield an accurate result for these quantities only when the composition of the medium matches approximately that of the standard reference solutions. In general, this test method will not give an accurate measure of hydrogen ion activity unless the pH lies between 2 and 12 and the concentration of neither electrolytes nor nonelectrolytes exceeds 0.1 mol/L (M). 1.2 The values stated in SI units are to be regarded as standard. The values in parentheses are for information only. 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 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 pH is, within the limits described in 1.1 , an accurate measurement of the hydrogen ion concentration and thus is widely used for the characterization of aqueous solutions. 4.2 pH measurement is one of the main process control variables in the chemical industry and has a prominent place in pollution control.