激光探针等离子体质谱测定NIST硅酸盐玻璃标样中痕量元素

Determination of Trace Elements of NIST Silicate Glass by Laser Probe Inductively Coupled Plasma Mass Spectrometry

采用激光探针等离子体质谱技术 ,以 42 Ca为内标 ,经预熔样处理 ,获得 NIST硅酸盐玻璃标样中 2 4种痕量元素 (Rb、Sr、REE、Th、U等 )的含量。结果表明 :方法的检出限在取样孔径 5 0 μm条件下可达 <1 0 -7(U、Th)～ <1 0 -6(REE) ,以 NIST61 2的一点为标准测定其它点 ,大多数元素的精密度优于± 1 0 % ;以NIST61 2为标准测定 NIST61 0 ,大多数元素的准确度优于± 1 0 %。

The concentrations of the twenty-four species of trace elements such as Rb, Sr, REE, Th and U of NIST silicate glass are obtained with laser probe inductively coupled plasma mass spectrometry technique. The signal variation of representative isotopes such as 42 Ca, 139 La, 175 Lu, 208 Pb and 238 U versus ablation time for a typical sampling spot on NIST612 is firstly investigated. It is shown that the signal of measured isotopes is stable after 30 seconds and the inter-element fractionation between Ca and other elements is negligible after 20 seconds. 42 Ca was chosen as an internal standard. Detection limits determined by 3σ of carrier gas blank are found to be lower than 10 -7 for U and Th to lower than 10 -6 for REE with an ablation crater of about 50 μm. The precision is better than 10% for most elements such as REE, U, Th and Pb according to analyses of 6 sampling spot of NIST612 using NIST612 itself as a calibrated standard. The accuracy is also better than 10% for most elements according to analyses of NIST610 using NIST612 as a calibrated standard.