电感耦合等离子体原子发射光谱法测定球墨铸铁中8种元素

为了优化球墨铸铁样品的溶样问题,实验重点探讨了不同酸的溶样效果。优选了溶解样品所用混合酸的种类和体积为HCl 15mL、HNO_35mL、HClO_45mL;样品中含有不溶碳化物,加入HClO_4溶解,加热至冒HClO_4烟并等待3~5min,取下并冷却,加10mL H_2O、5mL HCl摇匀,再加5mL HNO_3,加热溶解盐类后可得待测试液,实现了电感耦合等离子体原子发射光谱法(ICP-AES)对球墨铸铁中Mn、Cu、Mg、Co、V、Ti、Ni、Cr 8种元素的同时测定。加入HCl-HNO_3混酸(1∶1,V/V)控制待测液的酸度为10%(V/V);采用基体匹配的方法消除了基体效应;此外,通过选择合适的谱线,有效消除了待测元素之间的干扰。将实验方法用于球墨铸铁标准样品的分析,测定值与认定值一致,6次测定结果的相对标准偏差(RSD)均在3%以内;用于球墨铸铁实际样品的分析结果也与国标方法(GB/T 223系列)的测试结果基本吻合。

Determination of eight elements in nodular cast iron by inductively coupled plasma atomic emission spectrometry

In order to optimize the sample preparation of nodular cast iron, the dissolution with different acids was focused on and discussed. The optimum type and volume of mixed acid for sample dissolution were listed as follows: 15 mL of HCl, 5 mL of HNO₃ and 5 mL of HClO₄. The sample contained insoluble carbides which were dissolved by adding HClO₄. The solution was heated until HClO₄ fume appeared for 3-5 min. After cooling, 10 mL of H₂O and 5 mL of HCl were added followed by shaking up. Then 5 mL of HNO₃ was added to dissolve the salts to prepare the testing solution. The simultaneous determination method of eight elements (including Mn, Cu, Mg, Co, V, Ti, Ni and Cr) in nodular cast iron by inductively coupled plasma atomic emission spectrometry (ICP-AES) was established. The HCl-HNO₃ mixture (1∶1, V/V) was added to control the acidity of testing solution at 10% (V/V). The matrix effect was eliminated by matrix matching method. In addition, the proper spectral lines were selected to effectively eliminate the interference among testing elements. The proposed method was applied for the analysis of nodular cast iron CRMs, and the found results were consistent with the certified values. The relative standard deviations (RSD, n=6) were all less than 3%. The actual sample of nodular cast iron was also determined according to the experimental method, and the analysis results were basically consistent with those obtained by national standard method (GB/T 223 series).