Matrix-assisted photochemical vapor generation for determination of trace bismuth in Fe-Ni based alloy samples by inductively coupled plasma mass spectrometry

As the impurities in alloy may affect its mechanical and physical properties, the determination of trace elements is important to ensure the quality of alloy. However, accurate determination of trace impurities in alloy samples is a big challenge due to their complicated matrix and low concentrations. In this work, matrix-assisted photochemical vapor generation (PVG) was developed for the determination of impurity in alloy samples by inductively coupled plasma mass spectrometry (ICPMS). Bismuth was selected as the target element, which is detrimental to the strength of alloy even at very low concentration. The transition ions existed in alloy worked as the "sensitizers" for the efficient PVG of bismuth, and only formic acid and acetic acid were required for the analysis of alloy samples after digestion. This largely reduced the risks of sample contamination and analyte loss in multiple sample pretreatment involved in conventional analytical methods. The PVG efficiency of bismuth was greatly enhanced, making the sensitive and simple determination of trace analytes in alloy samples feasible. The limit of detection (LOD, 3 sigma) for Bi was found to be 0.4 ng L-1 corresponding to 0.54 ng g(-1) for analysis of 0.5 g of alloy sample. A relative standard deviation (RSD) of 1.1% was obtained from seven replicate measurements of 0.5 mu gL(-1) Bi3+ in sample matrix. The proposed method was successfully applied for the determination of Bi in two certified reference materials (Fe-Ni based alloys GBW01621 and GBW01622).