电工技术产品中某些物质的测定. 第7-2部分: 六价铬. 采用比色法测定电子聚合物中的六价铬(Cr(VI))

[中文适用范围]： IEC 62321 的这一部分描述了定量测量聚合物和电子产品样品中六价铬 Cr(VI) 的程序。该方法采用有机溶剂溶解或溶胀样品基质，然后通过碱消解程序从样品中提取 Cr(VI)。研究表明，从可溶性和不溶性样品中萃取 Cr(VI) 时，有机/碱性溶液比酸性溶液更有效。在碱性条件下，Cr(VI) 还原为 Cr(III) 或 Cr(III) 氧化为 Cr(VI) 的情况极少。对于由 ABS（丙烯腈-丁二烯-苯乙烯）、PC（聚碳酸酯）和 PVC（聚氯乙烯）组成的可溶性聚合物，首先将样品溶解在适当的有机溶剂中，然后通过碱萃取来萃取 Cr(VI)解决方案。对于不溶/未知聚合物或不含锑 (Sb) 的电子材料，样品在 150 °C 至 160 °C 的甲苯/碱性溶液中消解。然后分离萃取物中的有机相并弃去；保留无机相用于 Cr(VI) 分析。提取物中 Cr(VI) 的浓度通过其在酸性条件下与 1,5-二苯卡巴肼的反应来测定。 Cr(VI) 在与二苯基卡巴肼反应时被还原为 Cr(III)，二苯基卡巴肼被氧化为二苯基卡巴腙。 Cr(III) 和二苯基卡巴腙在反应中形成红紫色络合物。通过比色计或分光光度计在540 nm处定量测量络合物溶液。 [外文原描述]： IEC 62321-7-2:2017 describes procedures to measure hexavalent chromium, Cr(VI), quantitatively in samples of polymers and electronics. This method employs organic solvent to dissolve or swell the sample matrix, followed by an alkaline digestion procedure to extract Cr(VI) from samples. Studies have shown that organic;alkaline solution is more effective than acidic solution in extracting Cr(VI) from soluble and insoluble samples. Minimal reduction of Cr(VI) to Cr(III) or oxidation of Cr(III) to Cr(VI) occurs under alkaline conditions. The first edition of IEC 62321:2008 was a 'stand-alone' standard that included an introduction, an overview of test methods, a mechanical sample preparation as well as various test method clauses. This first edition of IEC 62321-7-2 is a partial replacement of IEC 62321:2008, forming a structural revision and generally replacing Annex C. IEC 62321-7-2 is the final replacement part of the corresponding clauses in IEC 62321:2008. It has the status of a horizontal standard in accordance with IEC Guide 108 .