稀土金属及其氧化物中非稀土杂质 化学分析方法 第21部分：稀土氧化物中硫酸根 含量的测定　硫酸钡比浊法 Chemical analysis methods for non-rare earth impurities of rare earth metals and their oxides— Part 21：Determination of sulfate radical content in rare earth oxides—Barium sulfate turbidimetry  ICS  77.120.99 CCS  H 14   中华人民共和国国家标准 GB/T 12690.21—2024 2024-10-2 6发布 2025-05-0 1实施     国家市场监督管理总局 国家标准化管理委员会 发 布 目　　次 前言   ·····································································································   Ⅲ 引言   ·····································································································   Ⅳ 1     范围   ··································································································   1 2     规范性引用文件   ······················································································   1 3     术语和定义   ···························································································   1 4     原理   ··································································································   1 5     试剂或材料   ···························································································   1 6     仪器设备   ······························································································   2 7     样品   ··································································································   2 8     试验步骤   ······························································································   2      8.1     试料   ······························································································   2      8.2     平行试验   ·························································································   2      8.3     空白试验   ·························································································   2      8.4     分析试液的制备   ·················································································   2      8.5     测定   ······························································································   3      8.6     标准曲线的绘制与测定   ··········································································   3 9     试验数据处理   ·························································································   4 10     精密度   ·······························································································   4      10.1     精密度原始数据及统计   ·········································································   4      10.2     重复性   ··························································································   4      10.3     再现性   ··························································································   5 GB/T 12690.21—2024     Ⅰ