1.1 这些试验方法包括测定水和废水中0.05至1.0 mg/L氮范围内的亚硝酸盐氮、硝酸盐氮和组合亚硝酸盐氮。两种测试方法 2. 如下所示: 小节 试验方法A-自动镉还原 9 到 18 试验方法B-手动镉还原 19 到 28 1.2 这些试验方法适用于地表水、盐水、废水和地下水。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。 1.3 以国际单位制或英寸-磅单位表示的数值应视为标准。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。 有关具体的危险说明，请参阅 8.2 . 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====== 5.1 两种测试方法使用相同的试剂和样品处理。这两种方法之间的唯一区别是，一种测试方法是自动的，另一种是手动的。范围和干扰是相同的。 5.2 当需要分析大量样品时，首选自动测试方法。手动测试方法用于较少的样本或当无法使用自动仪器时。 5.3 这些试验方法取代了试验方法 D1254 （亚硝酸盐）和 D992 （硝酸盐）。亚硝酸盐试验方法（试验方法 D1254 )使用被认为是潜在致癌物的试剂。硝酸盐试验方法（试验方法 D992 )已证明，在废水中使用时存在相对较大的误差，并且比本文所述的试验方法具有更大的操作困难。 5.4 试验方法 D7781 使用硝酸还原酶将硝酸盐还原为亚硝酸盐。镉被认为是有毒金属。此外，异相镉还原剂比本试验方法中描述的还原更困难。

1.1 These test methods cover the determination of nitrite nitrogen, nitrate nitrogen, and combined nitrite-nitrate nitrogen in water and wastewater in the range from 0.05 to 1.0 mg/L nitrogen. Two test methods 2 are given as follows: Sections Test Method A—Automated Cadmium Reduction 9 to 18 Test Method B—Manual Cadmium Reduction 19 to 28 1.2 These test methods are applicable to surface, saline, waste, and ground waters. It is the user's responsibility to ensure the validity of these test methods for waters of untested matrices. 1.3 The values stated in either SI or inch-pound units are to be regarded as the 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. For specific hazard statements, see 8.2 . 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 ====== 5.1 Both test methods use identical reagents and sample processing. The only difference between the two methods is that one test method is automated and the other is manual. The ranges and interferences are identical. 5.2 The automated test method is preferred when large numbers of samples are to be analyzed. The manual test method is used for fewer samples or when automated instrumentation is not available. 5.3 These test methods replace Test Methods D1254 (Nitrite) and D992 (Nitrate). The nitrite test method (Test Method D1254 ) used a reagent that is considered to be a potential carcinogen. The nitrate test method (Test Method D992 ) has been shown to have relatively large errors when used in wastewaters and also has greater manipulative difficulties than the test method described herein. 5.4 Test Method D7781 uses a nitrate reductase enzyme for the reduction of nitrate to nitrite. Cadmium is considered a toxic metal. Also, the heterogeneous cadmium reductant creates greater difficulty than the reduction described in this test method.