辉光放电质谱法测定纯锡中24种杂质元素和锡记忆效应的消除

采用辉光放电质谱法(GDMS)测定了纯锡中24种杂质元素,分析方法为无标定量分析。分析前纯锡样品须依次用乙醇、水及乙醇冲洗以除去表面的灰尘颗粒,凉干后用于分析。本工作对辉光放电过程中的三项关键因素,即辉光放电电压、放电电流及放电气流三者在辉光放电溅射/电离时的相互关系及其对总离子流强度的影响进行了试验和讨论,并确定了仪器在最佳状态时辉光放电的优化条件为:放电电压590V,放电电流30mA,放电气流450mL·min^-1。为排除各元素测定中质谱(MS)干扰的影响,选择了在不同的分辨模式(中/高)下用相对丰度较高、干扰较少的质量数进行分析。所测定元素测定结果的相对标准偏差(n=5)均小于15%。各元素的检出限(3s)为0.003~0.174μg·g^-1之间。本方法所得测定结果与电感耦合等离子体原子发射光谱法(ICP-AES)或电感耦合等离子体质谱法(ICP-MS)的测定结果基本一致。经试验,通过更换GDMS的阳极帽、导流管、采样锥和透镜等4种耗材,可完全消除锡的记忆效应。

Glow Discharge Mass Spectrometric Determination of 24 Impurity Elements in Pure Tin and Elimination of Memory Effect of Tin

Glow discharge mass spectrometry(GDMS)was applied to the determination of 24impurity elements in pure tin,with quantification without reference standards.The pure tin sample should be washed with ethanol,water and ethanol again in succession to remove dust particles from its surface,and then be air-dried before used for analysis.The inter-relationship among the 3key influential factors,i.e.,the voltage,current and gas-flow of glow discharge,and their influences to the intensity of total ionization current during the process of glow discharge supttering and ionization were tested and discussed in this work.And the optimized conditions of glow discharge,under which the GDMS instrument behaved its best state,were found as follows:voltage of 590V,current of 30mA and gas flow of 450mL·min^-1.Mass numbers with higher relative abundance and with less interference under different resolution modes(middle or high)were selected for the analysis,to eliminate the influence of MS interferences in the determination of the impurity elements.Values of RSDs(n=5)found for the elements determined were all less than 15%.Detection limits(3s)found for the 24elements were in the range of 0.003-0.174μg·g^-1.The analytical results of the elements determined by the present method were found in consistency basically with those found by ICP-AES or ICP-MS.It was shown by the testing result that the memory effect of tin was completely eliminated by renewing 4of the easy-consumable spares of the instrument,i.e.,the anode cap,the current duct,the sampling cone and the lens.