采用电感耦合等离子体质谱法(ICP-MS)测定转炉石墨球样品中痕量Tl时,其含有的Hg、Pb和稀土元素(Ir、Os、Re等)会以氢化物多原子离子(1H204Hg+、1H204Pb+)和稀土化合物离子(12C193Ir+、14N191Ir+、16O189Os+、18O187Re+)形式对205Tl+的测定产生多原子离子质谱干扰.将样品于 750 ℃ 灼烧 1 h 后用 10 mL HCl-10 mL HNO3-5 mL HF-3 mL HClO4 体系溶解样品;在串联四级杆(MS/MS)模式下,设置一级质量过滤器(Q1)的质荷比(m/z)为205,使得205 Tl+与12C193Ir+、14N191Ir+、16O189Os+、18O187Re+等进入碰撞反应池;同时,在反应池中通入O2,使205Tl+和O2反应生成205Tl16O+,而干扰离子不与O2发生反应;将二级质量过滤器(Q2)的m/z设置为221,只有205Tl16O+通过并进入检测器中,从而消除了质谱干扰.据此,建立了氧气反应模式-电感耦合等离子体串联质谱法(ICP-MS/MS)测定转炉石墨球中痕量Tl的方法.对O2流量进行了优化,选择O2流量为0.5 mL/min;考察了基体效应和内标校正的效果,结果表明,基体效应可忽略,选择5 μg/L In为内标校正可克服仪器信号漂移对测定的影响.方法线性范围为0.01～1.00 μg/L,线性相关系数为0.999 8,检出限为0.000 65 μg/g,定量限为0.002 0 μg/g.按照实验方法对转炉石墨球样品中Tl进行加标回收试验,回收率在95％～105％之间.采用所建立的方法对转炉石墨球样品中Tl进行测定,结果的相对标准偏差(RSD,n=11)为1.6％～2.4％,测定值与石墨炉原子吸收光谱法测得结果基本一致.
Determination of trace thallium in converter graphite sphere by inductively coupled plasma tandem mass spectrometry at oxygen reaction mode
During determination of trace Tl in converter graphite sphere sample by inductively coupled plas-ma mass spectrometry(ICP-MS),the coexisting elements,including Hg,Pb,and rare earth elements(Ir,Os,Re,etc)will cause polyatomic interference with the determination of 205Tl+in the form of hydride pol-yatomic ions(1H204Hg+,1H204Pb+)and rare earth compound ions(12C193Ir+,14N191Ir+,16O189Os+and 18O187Re+).The sample was calcinated at 750 ℃ for 1 h and then dissolved with 10 mL HCl-10 mL HNO3-5 mL HF-3 mL HClO4 system.In tandem quadrupole(MS/MS)mode,the mass-to-charge ratio(m/z)of the first-stage mass filter(Q1)was set to 205,so that 205 Tl+entered the collision reaction pool with 12C193Ir+,14N191Ir+,16O189Os+,18O187Re+,etc.At the same time,O2 was introduced into the collision reac-tion cell,which could react with 206Tl+to form 205Tl16O+,while the interference ions did not react with O2.The m/z of the second-stage mass filter(Q2)was set to 221,so that only 205Tl16O+could pass through and entered the detector,thus eliminating the mass spectral interference.Based on this,a method for determination of trace Tl in converter graphite sphere by inductively coupled plasma tandem mass spec-trometry(ICP-MS/MS)at oxygen reaction mode was established.The flow rate of O2 was optimized and 0.5 mL/min was selected.The matrix effect and the effect of internal standard correction were investiga-ted.The results showed that the matrix effect could be ignored,and the influence of instrument signal drift on the determination could be overcome by the internal standard correction of 5 μg/L In.The linear range of this method was 0.01-1.00 μg/L,the linear correlation coefficient was 0.999 8,the limit of detec-tion was 0.000 65 μg/g,and the limit of quantification was 0.002 0 μg/g.The recovery tests of Tl in con-verter graphite sphere sample were conducted according to the proposed method,and the recoveries were between 95％and 105％.The contents of Tl in converter graphite sphere samples were determined by the proposed method.The relative standard deviations(RSD,n=11)were between 1.6％-2.4％,and the re-sults were basically consistent with graphite furnace atomic absorption spectrometry.
converter graphite spherethalliuminductively coupled plasma tandem mass spectrometry(ICP-MS/MS)oxygen reaction mode
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