电感耦合等离子发射光谱法测定氧化铁颜料中微量镉

Determination of cadmium in ferric oxide pigments by ICP-OES

在用电感耦合等离子体发射光谱测定氧化铁颜料中的镉时,镉常用的3条谱线Cd214.439,Cd226.502和Cd228.802均受到铁光谱不同程度的干扰。实验采用铑作内标,在0~20.0 g/L的铁质量浓度范围内,研究了铁在这3条谱线下的干扰大小。结果发现Cd226.502干扰最大,Cd214.439干扰次之,Cd228.802干扰最小,干扰质量浓度分别在0.130~1.430 mg/L、0.031~0.329 mg/L和0.005~0.025 mg/L之间;铁在Cd226.502、Cd214.439的干扰随铁质量浓度的增加而增加,增幅均较明显;铁在Cd228.802的干扰随铁质量浓度变化影响不大。最终用Cd228.802进行筛选分析,对于0.500 g样品称取量,当结果≤5.0 mg/kg时判定合格,结果>6.2 mg/kg时判定为不合格,只有当结果介于二者之间时,再用其他方法进行分析确认。因此,用Cd228.802进行分析,可以大大提高筛选效率。

Cd214.439,Cd226.502 and Cd228.802,commonly used in determination of cadmium in ferric oxide pigments by ICP-OES,are interfered by the iron spectrum.By using rhodium as the internal standard,the interference at these three spectral lines in the mass concentration range of 0-20.0 g/L of iron was studied.The results showed that,iron interfered most at Cd226.502,next at Cd214.439,and least at Cd228.802.The interference values ranged from 0.130-1.430 mg/L,0.031-0.329 mg/L,and 0.005-0.025 mg/L,respectively.At Cd226.502 and Cd214.439,the interference intensity grew with the increase of iron mass concentration,but not so much at Cd228.802.Finally,Cd228.802 was selected for screening analysis.The sample was weighed as 0.500 g,which could be judged as qualified when the test result was less than or equal to 5.0 mg/kg,and unqualified when the test result was more than 6.2 mg/kg.Only when the test result was somewhere in between,other methods would be used for analysis and confirmation.Therefore,the selection of Cd228.802 for analysis could greatly improve the screening efficiency.