Non-matrix matched calibration of major and minor concentrations of Zn and Cu in brass, aluminium and silicate glass using NIR femtosecond laser ablation inductively coupled plasma mass spectrometry

Abstract

The feasibility of using near-infrared (NIR) femtosecond laser ablation (fs-LA) inductively coupled plasma mass spectrometry (ICP-MS) for the analysis of solid samples with non-matrix matched standard reference materials was studied. Major and minor concentrations of Zn and Cu (433 μg g⁻¹–0.95 g g⁻¹) were measured in three sets of metallic and dielectric standards (brass, aluminium, silicate glass) using He as the ablation cell gas and, with admixed Ar, for aerosol transportation from the cell into an Ar-ICP-MS instrument. Not surprisingly for ICP-MS detection, the experimental Zn/Cu ion ratios were found to be dependent on the sampler cone position in the plasma. However, at a fixed sampler position the experimental Zn/Cu ratios of the brass and Al samples were found to be proportional to the certified ratios independent of the laser fluence applied (range: 2–42 J cm⁻²). In contrast, the Zn/Cu ratio of an optical transparent glass sample (NIST 610) was found to be strongly fluence dependent. However, with increasing fluence the measured ratio asymptotically approached the experimentally expected ratio taking into account the results obtained from the brass and aluminium measurements.