将镁砂样品0.200 0 g用混合助熔剂(碳酸钠与硼酸按质量比2∶1混合) 2.0 g于950~1 000 ℃熔融20 min,冷却后,用25%(体积分数)盐酸溶液100 mL低温加热至熔融物完全溶解。加入100 mg·L^-1的钇标准溶液4 mL,用水定容至200 mL。采用基体加标校正、内标校正,以电感耦合等离子体原子发射光谱法(ICP-AES)同时测定上述溶液中氧化钙、二氧化硅、三氧化二铁、三氧化二铝、五氧化二磷、二氧化钛、氧化锰的含量。辅以灼烧失量校正,采用差减法计算氧化镁的含量。结果表明,各成分的质量分数在一定范围内与各成分与内标的发射强度比呈线性关系,检出限(3s)为0.000 9%~0.009 6%。对同一样品平行测定9次,测定值的相对标准偏差(n=9)均小于3.0%。方法用于测定镁砂标准样品,所得测定值与认定值基本一致。

The magnesia sample (0.200 0 g) was melted at 950-1 000 ℃ for 20 min with 2.0 g of mixed assistant flux (sodium carbonate and boric acid mixed at a mass ratio of 2∶1). After cooling, it was heated at low temperature with 100 mL of 25% (volume fraction) hydrochloric acid solution until the melt was completely dissolved. 4 mL of 100 mg·L^-1 yttrium standard solution was added, and the solution was made up to 200 mL with water. Calcium oxide, silicon dioxide, ferric oxide, aluminum oxide, phosphorus pentoxide, titanium dioxide and manganese oxide in the above solution were simultaneously determined by inductively coupled plasma atomic emission spectrometry (ICP-AES) using matrix spiking correction and internal standard correction, and the content of magnesium oxide was calculated by subtraction method with ignition loss correction. As shown by the results, linear relationships between the emission intensity ratio of each component to the internal standard and mass fraction of each component were found in definite ranges, with detection limits (3s) of 0.000 9%-0.009 6%. The sample was determined 9 times, with RSDs of determined values less than 3.0%. This method was applied to the determination of magnesia standard samples, and the determined values were basically consistent with the certified values.