Pulsed radiofrequency glow discharge time of flight mass spectrometry for coated glass analysis
The analytical potential of radiofrequency pulsed glow discharge time of flight mass spectrometry (rf-PGD-ToFMS) is investigated for quantitative depth profiling analysis of glasses and thin conductive and non-conductive layers on glasses. PGD in combination with ToFMS can allow the reduction or even removal of spectral interferences by selecting a proper GD pulse interval. Thus, discrimination of potential polyatomic interferences for several analytes (e.g., 28Si+, 39K+, 44Ca+, and 48Ti+) was investigated by selecting appropriate time positions along the GD pulse profile. In this paper, the determination of compositional depth profiles of coated glasses was performed by resorting to a multi-matrix calibration procedure. For this purpose, conductive as well as non-conductive certified reference materials were employed to build the analytical calibration curves. Results show that rf-PGD-ToFMS allows us to discriminate the different layers of the samples and the nominal values for element concentrations and layer thicknesses were in agreement with experimental results obtained using the proposed quantification strategy. Moreover, the capability of rf-PGD-ToFMS to provide a full mass spectrum every 33 μs enable the identification of unexpected elements which can be present as contaminants in very thin layers (e.g. Cd, Sn, Te and Sb).