1.1 本试验方法涵盖了废水、地表水和饮用水中溶解六价铬的测定程序。 1.2 该测试方法的精度和偏差已在试剂水和工业废水中进行了测试，发现其适用范围约为1至1000μg/L。可以通过适当的稀释来确定更高的水平。 1.3 含有非常高水平阴离子物种（即氯化物、硫酸盐等）的样品可能会导致色谱柱过载。含有高水平还原物种（即硫化物、亚硫酸盐等）的样品可能会导致Cr（VI）还原为Cr（III）。通过将样品缓冲至9至9.5的pH值，过滤，将其储存在<6°C的温度下，可以将其降至最低。如果用户能够证明，根据美国EPA 40 CFR 136第二部分的规定，这种保持时间不会影响样品的完整性，则可以使用28天的保持时间。 1.4 以国际单位制表示的数值应视为标准值。 括号中给出的值是英寸-磅单位的数学转换，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。 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====== 5.1 六价铬盐广泛用于金属表面处理和电镀行业，在皮革行业用作鞣剂，并用于制造油漆、染料、炸药和陶瓷。 三价铬盐在纺织染色、陶瓷和玻璃工业以及摄影中用作媒染剂。无论处于哪种氧化状态，铬都可能存在于这些行业的废水中，也可能从铬酸盐处理的冷却水中排放。 5.2 六价铬对人类、动物和水生生物有毒。吸入后可产生肺部肿瘤，并容易引起皮肤过敏。目前尚不清楚摄入任何价态的铬是否会导致癌症。 5.3 离子色谱法提供了一种从样品中存在的其他物种中分离六价铬的方法，其中许多物种干扰了其他检测方法。这种分离与灵敏的比色检测方法相结合，为六价铬提供了一种选择性和灵敏的分析方法，只需最少的样品制备。

1.1 This test method covers procedures for the determination of dissolved hexavalent chromium in wastewater, surface water, and drinking water. 1.2 The precision and bias of this test method has been tested in reagent water and industrial wastewater and has been found suitable over the range of approximately 1 to 1000 μg/L. Higher levels can be determined by appropriate dilution. 1.3 Samples containing very high levels of anionic species (that is, chloride, sulfate, etc.) may cause column overload. Samples containing high levels of reducing species (that is, sulfides, sulfites, etc.) may cause reduction of Cr(VI) to Cr(III). This can be minimized by buffering the sample to a pH of 9 to 9.5, filtering it, storing it at <6°C. A holding time of 28 days may be used if the user can demonstrate that such holding time does not affect sample integrity in accordance with U.S. EPA 40 CFR 136, Part II. 1.4 The values stated in SI units are to be regarded as standard. The values given in parentheses are mathematical conversions to inch-pound units that 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. 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 ====== 5.1 Hexavalent chromium salts are used extensively in the metal finishing and plating industries, in the leather industry as a tanning agent, and in the manufacture of paints, dyes, explosives, and ceramics. Trivalent chromium salts are used as mordants in textile dying, in the ceramic and glass industry, and in photography. Chromium, in either oxidation state, may be present in wastewater from these industries and may also be discharged from chromate-treated cooling waters. 5.2 Hexavalent chromium is toxic to humans, animals, and aquatic life. It can produce lung tumors when inhaled and readily induces skin sensitization. It is not known whether cancer will result from ingestion of chromium in any of its valence states. 5.3 Ion chromatography provides a means of separating the hexavalent chromium from other species present in the sample, many of which interfere with other detection methods. The combination of this separation with a sensitive colorimetric detection method provides a selective and sensitive analytical method for hexavalent chromium with minimal sample preparation.