Accurate Determination Of Elements In Silicate Glass By Nanosecond And Femtosecond Laser Ablation ICP-MS At High Spatial Resolution

Laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) has become one of the most popular techniques for the in situ analysis of element and isotopic compositions for solid materials. In recent decade, the performance characteristics of LA-ICP-MS have been strongly enhanced, principally with the use of a shorter laser ablation wavelength and pulse width. However, elemental fractionation remains the main limitation for accurately quantitative analysis of LA-ICP-MS. This limitation is particularly notable for high spatial resolution analysis. In this study, we have further investigated the elemental fractionation and mass-load effect in the analysis of silicate glass by using 193 nm ArF excimer nanosecond laser and 257 nm femtosecond (fs) laser ablation systems coupled to inductively coupled plasma mass spectrometry. The results of the analysis of silicate glass show that:1、Contrary to those observed in nanosecond laser ablation, the most elemental fractionation at the small spot sizes of 16-24 μm are lower than that at the large spot sizes of 44-60 μm in fs-LA-ICP-MS.2、The significantly different fractionation behavior of Li,Na, Si,K,V,Cr, Mn,Fe,Co, Ni,Cu,Rb,Cs and U between synthetic silicate glass NIST SRM 61X and natural silicate glass materials observed in 193 nm LA-ICP-MS at high spatial resolution of 16-24 μm. Compared with natural silicate glass materials, the laser-induced elemental fractionation for these elements in synthetic silicate glass NIST SRM 61X are smaller.3、The special fractionation behavior for these elements in synthetic silicate glass NIST SRM 61X are reduced by using fs-LA-ICP-MS. The elemental fractionation for Zn,Cd,Pb and Bi in fs-LA-ICP-MS are much more serious than that in 193 nm LA-ICP-MS. 4、The mass load effect and matrix dependent mass load effect are smaller by using femtosecond laser ablation ICP-MS.5、The agreement between our data and the reference values is better than 10% for most of the elements in MPI-DING,USGS, and NIST glasses by using femtosecond laser ablation analysis at the small spot size of 24 μm. For nanosecond laser ablation analysis, the accuracy is highly dependent on the calibration strategies used (conventional external calibration method or 100% oxide normalization method) and the selected external reference materials (NIST SRM 610 or GSE-1G). In general, the much less laser-induced elemental fractionation and matrix effect in fs-LA-ICP-MS in comparison with 193 nm LA-ICP-MS make it more suitable for the analysis of silicate materials at high spatial resolution.