激光烧蚀-电感耦合等离子体质谱法测定高温合金中痕量元素的分馏效应及其校正

采用213 nm激光系统,详细考察了激光能量、剥蚀孔径、激光频率、离焦距离、剥蚀时间对电感耦合等离子体质谱法(ICP-MS)测定镍基高温合金中硼、镁、磷、铜、锌、镓、砷、银、铟、镉、锡、锑、铊、铅、铋等元素分馏效应的影响。试验表明,痕量元素的绝对分馏因子随上述参数的变化而变化,但主要影响因素是离焦距离和剥蚀孔径尺寸。当激光输出能量为70%、80%和90%时,大部分元素的绝对分馏因子在0.95～1.15之间;激光频率为10 Hz和15 Hz时多数元素的绝对分馏因子在1.0～1.1之间;激光剥蚀孔径为65、80和100 μm时各元素绝对分馏因子在0.90～1.15之间;离焦距离在+100～-100 μm之间变化时,各元素的绝对分馏因子在0.90～1.1之间;剥蚀时间在60～120 s之间时大部分元素的分馏因子在0.90～1.1之间。在优化的条件下,选择⁶⁰Ni或⁴⁷Ti作内标可以有效地校正剥蚀过程中元素信号随时间的变化,校正后大部分元素的分馏因子在0.95～1.1之间,但随着剥蚀时间的延长内标的校正效果有所降低。

Fractionation effect of laser ablation-inductively coupled plasma mass spectrometric determination oftrace elements in superalloy and its calibration

The fractionation effect of laser energy, ablation aperture, laser frequency, off-focus distance, ablation time on the determination of elements in high temperature nickel-based supperalloy such as B,Mg,P,Cu,Zn,Ga,As,Ag,In,Cd,Sn,Sb,Tl,Pb,Bi by inductively coupled plasma mass spectrometry (ICP-MS) was investigated with 213 nm laser system. It was indicated through experiment that the absolute fractionation factor of trace element varied along with the change of the above parameters, among which the main influence factors were off-focus distance and ablation aperture. When laser output energy was 70%, 80% and 90%, the absolute fractionation factor of most elements was 0.95-1.15; when laser frequency was 10 Hz and 15 Hz, the absolute fractionation factor of most elements was 1.0-1.1; when ablation aperture was 65, 80 and 100 μm, the absolute fractionation factor of each element was 0.90-1.15; when the off-focus distance varied between +100 and -100 μm, the absolute fractionation factor of each element was 0.90-1.1; when the ablation time was 60-120 s, the fractionation factor of most element was 0.90-1.1. Under optimized conditions, the variation of element signal along with time during ablation process could be effectively corrected with ⁶⁰Ni or ⁴⁷Ti as internal standard. After correction, the fractionation factor of most elements was in the range of 0.95-1.1, but along with the prolonging of ablation time, the correction effect decreased.