Over the past couple of years, spatially resolved analysis via laser ablation - ICP-MS through multiple parallel line scans on the surface of the sample has been increasingly used to visualize the 2D distribution of target elements in various types of samples. For that purpose, the laser beam is scanned across the surface of the sample along parallel lines and the data obtained upon analysis are handled such that a “map” of the element distribution is obtained. An example of the mapping of a Delft Blue tile artefact is given in Figure 1, showing the tile prior to ablation in the laser ablation chamber, and in Figure 2 the maps generated for 53 elements are given. Both “positive” and “negative” images can be seen in Figure 2, with positive correlations between the Co image and other images indicative for the presence of (trace) elements in the blue Co pigment (or ore).

Figure 1: Delft Blue tile cut to size to fit in the laser ablation chamber prior to ablation (NRW UP-213). In collaboration with Prof. N.H. Tennent.

Quantification of the elements in the tile was performed by a so-called sum normalization routine, summating the n (53 major, minor and trace) elements as their oxides to 100% wt using various glass standards to establish the sensitivity Si (in cps / % wt) for each element i [1, 2]:

Figure 2: Element maps for 53 elements (with a log(concentration) scale, from 0.000001 to 100% wt) related to the section marked for laser ablation as shown at the bottom right (line scans from left to right and from top to bottom); the horizontal and vertical scales denote the pixels (pixel size, 80 × 80 μm2), each maps having a size of 21.7 mm (w) × 30.0 mm (h). LA: NWR UP-213; ICP-MS: Agilent 7500ce.

References

  1. ELTEREN, J.T. van, TENNENT, N. H., ŠELIH, V.S. Multi-element quantification of ancient/historic glasses by laser ablation inductively coupled plasma mass spectrometry using sum normalization calibration. Analytica chimica acta, ISSN 0003-2670. [Print ed.], 2009, vol. 644, issues 1/2, str. 1-9
  2. SELIH, V.S., ELTEREN, J.T. van. Quantitative multi-element mapping of ancient glass using a simple and robust LA-ICP-MS rastering procedure in combination with image analysis. Analytical and bioanalytical chemistry, ISSN 1618-2642, 2011, vol. 401, no. 2, str. 745-755, doi: 10.1007/s00216-011-5119-8.