微波消解-电感耦合等离子体质谱法测定锌精矿中痕量铊

选取5 mL王水为溶剂,采用微波消解法处理锌精矿样品,以²⁰⁵Tl作为测定同位素,建立了电感耦合等离子体质谱法(ICP-MS)测定锌精矿中痕量Tl的定量分析方法。优化后的微波消解程序如下:消解温度为190 ℃,升温时间为20 min,消解保持时间为20 min。采用直接稀释法消除基体效应,控制测试液中固体质量浓度不大于0.5 mg/mL。实验表明,Tl质量浓度在0.10~50.00 μg/L范围内与其对应的峰强度呈良好的线性关系,校准曲线相关系数为0.999 9。方法检出限为0.001 8 μg/L,方法测定下限为0.006 μg/L。对锌精矿实际样品中的痕量Tl进行分析,测定结果与国家标准方法中泡塑富集-电感耦合等离子体原子发射光谱法(ICP-AES)测定值基本一致,相对标准偏差(RSD,n=11)均小于5%。

Determination of trace thallium in zinc concentrate by microwave digestion-inductively coupled plasma mass spectrometry

After the zinc concentrate sample was treated by microwave digestion with 5 mL of aqua regia as solvent, a quantitative analysis method of trace thallium in zinc concentrate was established by inductively coupled plasma mass spectrometry(ICP-MS) with ²⁰⁵Tl as determination isotope. The microwave digestion procedures were optimized as follows: the digestion temperature was 190 ℃, the temperature rising time was 20 min, and the digestion holding time was 20 min. The matrix effect was eliminated by direct dilution method, and the solid mass concentration in testing solution was controlled at not more than 0.5 mg/mL. The results showed that the mass concentration of thallium in range of 0.10~50.00 μg/L had good linearity to its corresponding peak strength. The correlation coefficient of calibration curve was 0.999 9. The detection limit of method was 0.001 8 μg/L, and the lower limit of determination was 0.006 μg/L. The content of trace thallium in zinc concentrate actual samples was determined according to the experimental method. The results were consistent with those obtained by national standard method, i.e., foam plastic enrichment-inductively coupled plasma atomic emission spectrometry(ICP-AES). The relative standard deviations (RSD, n=11) were less than 5%.