1.1 这些试验方法包括根据重铬酸盐溶液在规定条件下的还原来测定水中某些杂质将消耗的氧气量。包括以下试验方法: 试验方法A-回流消化和滴定法测定的宏观COD 试验方法B-密封消解和光谱法测定微量COD 1.2 这些试验方法受所用试剂的限制，最大化学需氧量（COD）为800 mg/L。COD浓度较高的样品可通过适当稀释样品进行处理。每种试验方法中的修改程序（第 15 对于试验方法A和章节 24 对于试验方法B），可用于低COD含量（<50 mg/L）的水。 1.3 一般来说，如果样品中氯含量超过1000 mg/L，则COD结果不准确 − . 因此，这些试验方法不应适用于海水和盐水等样品，除非样品按照中所述进行预处理 附录X1 . 1.4 该试验方法已成功用于试剂水中配制的标准品。用户有责任确保这些测试方法对未经测试的基质水的有效性。 1.5 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。 1.6 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 8. , 15.6 和 24.5 . 1.7 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====== 5.1 这些测试方法用于从化学上确定生物或自然化学过程因水中杂质而可能消耗的最大氧气量。通常，该测量用于监测和控制生活和工业废水中的耗氧污染物，包括无机和有机污染物。 5.2 文献中描述了COD与其他水质参数（如TOC和TOD）的关系。 3.

1.1 These test methods cover the determination of the quantity of oxygen that certain impurities in water will consume, based on the reduction of a dichromate solution under specified conditions. The following test methods are included: Test Method A — Macro COD by Reflux Digestion and Titration Test Method B — Micro COD by Sealed Digestion and Spectrometry 1.2 These test methods are limited by the reagents employed to a maximum chemical oxygen demand (COD) of 800 mg/L. Samples with higher COD concentrations may be processed by appropriate dilution of the sample. Modified procedures in each test method (Section 15 for Test Method A, and Section 24 for Test Method B) may be used for waters of low COD content (<50 mg/L). 1.3 As a general rule, COD results are not accurate if the sample contains more than 1000 mg/L Cl − . Consequently, these test methods should not be applied to samples such as seawaters and brines unless the samples are pretreated as described in Appendix X1 . 1.4 This test method was used successfully on a standard made up in reagent water. It is the user’s responsibility to ensure the validity of these test methods for waters of untested matrices. 1.5 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard. 1.6 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 8 , 15.6 , and 24.5 . 1.7 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 These test methods are used to chemically determine the maximum quantity of oxygen that could be consumed by biological or natural chemical processes due to impurities in water. Typically this measurement is used to monitor and control oxygen-consuming pollutants, both inorganic and organic, in domestic and industrial wastewaters. 5.2 The relationship of COD to other water quality parameters such as TOC and TOD is described in the literature. 3