1.1 本试验方法涵盖地表水、海水、地下水、废水和废水流出物中总氮（TN）和总溶解氮（TDN）的测定，浓度范围为0.2 mg/L N至10 mg/L N。当与手动或自动稀释或自动进样较少样品体积结合使用时，浓度范围为10 mg/L至500 mg/L是可能的。EPA 40 CFR第136部分附录B方法检测限（MDL）为0.05 mg/L N。可以通过样品稀释来确定更高浓度。通过注射较大的样品体积，可以获得较低的浓度。遵循制造商的说明。 1.2 将样品注射到加热至 ≥ 720°C。样品转化为气相，并被迫通过催化剂层，确保所有含氮化合物转化为氮氧化物(NO)。与臭氧的反应将NO转化为退出的NO 2 .作为兴奋的不 2 返回基态时，它会发出光电测量的辐射。 1.3 通过试验方法分析总有机碳和溶解有机碳 D7573 可以使用适当配备的分析仪同时对同一样品进行分析。（见 附录X1 对于同时TOC数据的示例。） 1.4 该测试方法可从多种有机和无机氮化合物中定量回收氮（见 表1 和 表2 ).试验方法不测量氮气（N 2 ).用户有责任确保本测试方法对未测试基质水的有效性。 1.5 本试验方法仅适用于样品中可引入反应区的含氮物质。注射器针头或注射器开口尺寸通常限制可以如此引入的颗粒的最大尺寸。可以使用任选的自动样品均化。 1.6 该测试方法基于性能。您可以进行修改以提高测试方法的性能，但不改变氧化或检测技术。 1.7 以SI单位表示的值将被视为标准值。本标准不包括其他计量单位。 1.8 本标准并不旨在解决与其使用相关的所有安全性问题（如果有）。本标准的使用者有责任在使用前建立适当的安全、健康和环境实践并确定法规限制的适用性。 1.9 本国际标准是根据《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世界贸易组织技术性贸易壁垒（TBT）委员会发布的修正案。 ======意义和用途====== 5.1 本试验方法用于测定各种天然、家用和工业水源水中的总氮或溶解氮含量。在其最常见的形式中，该测试方法用于测量氮，作为监测工业废水、生活废水和环境水中营养污染物的手段。这些测量也可用于监测废物处理过程。 5.2 该测试方法同时测量氧化氨和有机氮（硝酸盐）以及可溶性硝酸盐，从未消化的样品中减去硝酸盐+亚硝酸盐值，得到总凯氏氮（TKN）。 使用此测试方法时: 其中: TN = 总氮，和 天相投顾 = 总凯氏氮。

1.1 This test method covers the determination of total nitrogen (TN) and total dissolved nitrogen (TDN) in surface water, seawater, groundwater, wastewater, and wastewater effluents in the range from 0.2 mg/L N to 10 mg/L N. Concentrations from 10 mg/L to 500 mg/L are possible when used in conjunction with manual or automatic dilution, or automatic injection of less sample volume. The EPA 40 CFR Part 136 Appendix B Method Detection Limit (MDL) is 0.05 mg/L N. Higher concentrations may be determined by sample dilution. Lower concentrations may be possible by injecting larger sample volumes. Follow the manufacturer’s instructions. 1.2 The sample is injected onto a platinum catalyst heated at ≥ 720 °C. The sample converts into a gaseous phase and is forced through a layer of catalyst ensuring conversion of all nitrogen containing compounds to nitrogen oxide (NO). Reaction with ozone converts the NO to an exited NO 2 . As the excited NO 2 returns to the ground state, it emits radiation that is measured photo-electrically. 1.3 Total and dissolved organic carbon analysis by Test Method D7573 can be analyzed at the same time on the same sample simultaneously using a properly equipped analyzer. (See Appendix X1 for an example of simultaneous TOC data.) 1.4 This test method quantitatively recovers nitrogen from a large range of organic and inorganic nitrogen compounds (see Table 1 and Table 2 ). The test method does not measure nitrogen gas (N 2 ). It is the user's responsibility to ensure the validity of this test method for waters of untested matrices. 1.5 This test method is applicable only to nitrogenous matter in the sample that can be introduced into the reaction zone. The syringe needle or injector opening size generally limits the maximum size of particles that can be so introduced. Optional automatic sample homogenization may be used. 1.6 This test method is performance based. You may make modifications that improve the test method’s performance but do not change the oxidation or detection technique. 1.7 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard. 1.8 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. 1.9 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 This test method is used for determination of the total or dissolved nitrogen content of water from a variety of natural, domestic, and industrial sources. In its most common form, this test method is used to measure nitrogen as a means of monitoring nutrient pollutant in industrial wastewater, domestic wastewater, and ambient water. These measurements may also be used in monitoring waste treatment processes. 5.2 This test method measures oxidized ammonia and organic nitrogen (as nitrate) and soluble nitrate simultaneously, subtracting the nitrate + nitrite value from a non-digested sample gives total Kjeldhal nitrogen (TKN). When using this test method: where: TN = total nitrogen, and TKN = total Kjeldahl nitrogen.