1.1 本试验方法包括用铬化合物部分或全部鞣制的湿蓝中氧化铬的测定。通常，当计算为以干燥基础(也称为无水分基础(mfb))表示的氧化铬时，样品将含有1%至5%的铬含量。 1.2 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。 1.3 本试验方法不适用于湿白。 1.4 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。见第节 8 针对特定的安全隐患。 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》中确立的国际公认的标准化原则制定的。 ======意义和用途====== 5.1 所描述的程序对于湿蓝中的铬是特定的。钒是唯一常见的干扰元素，很少大量存在。当来自水污染或工艺化学品时，铁也可能通过赋予黄色来干扰，这可能会影响滴定的终点。加入磷酸以络合任何可能存在的铁。对于大多数市售湿蓝，铁含量不足以引起干扰（参见 表1 ).因此，对于大多数市售湿蓝，用户可以选择不使用磷酸。程序选项B提供了一种使用减小的样本量和更少的化学品来获得等效结果的方法（见 表1 这些方法的精密度和准确度通常至少与湿蓝本身的取样一样好。 5.2 湿蓝的铬含量与所获得的鞣制度有关，因此在购买湿蓝时可能是需要说明的事项。所描述的程序为此目的提供了足够的准确度。

1.1 This test method covers the determination of chromic oxide in Wet Blue that has been partly or completely tanned with chromium compounds. In general, the samples will contain chromium content between 1 % and 5 % when calculated as chromic oxide expressed upon a dry basis otherwise referred to as moisture-free basis (mfb). 1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard. 1.3 This test method does not apply to Wet White. 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. See Section 8 for specific safety hazards. 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 The procedure described is specific for chromium in Wet Blue. Vanadium is the only common interfering element and is rarely present in quantity. Iron, when present from either water contamination or process chemicals, may also interfere by imparting a yellow color which could affect the endpoint of the titration. Phosphoric acid is added to complex any iron that may be present. For most commercially available wet blue, the iron content is not sufficient to cause an interference (see Table 1 ). Therefore, for most commercially available wet blue, the user may opt to exclude use of the phosphoric acid. Procedure Option B offers a method that uses a reduced sample size and less chemicals to obtain equivalent results (see Table 1 ).The precision and accuracy of the methods are usually, at least, as good as the sampling of Wet Blue itself. 5.2 The chromium content of Wet Blue is related to the degree of tannage obtained, and hence may be a matter for specification in the purchase of Wet Blue. The procedure described provides adequate accuracy for this purpose.