Multi-element analysis of soils and sediments from Scottish historical sites. The potential of inductively coupled plasma-mass spectrometry for rapid site investigation

This study highlights the potential of inductively coupled plasma-mass spectrometry (ICP-MS) for the semi-quantitative, simultaneous multi-element analysis (SMA) of soils and sediments from historical settlement sites in Scotland. Semi-quantitative SMA is extremely quick (the turnover rate is approximately 15 samples per h) and is principally used for the rapid screening of samples. Here, it is shown that the semi-quantitative SMA of 32 elements is possible with acceptable levels of analytical precision following a HNO₃-HClO₄ digestion procedure, thereby allowing the archaeologist the opportunity to appraise a site of interest for a large suite of potentially important elements. However, due to severe spectral interference on P with ICP-MS, this element is better determined with an alternative technique such as automated photometric instrumentation. Furthermore, despite the fact that ICP-MS has a dynamic working range of about six orders of magnitude, it was not possible to determine simultaneously all of the elements potentially available for detection in this study. The major soil elements are typically present in too high a concentration to enable their simultaneous determination with elements of low abundance, such as the rare earth elements. Hence, the elements such as Ca, Mg and K, all of which are of potential value to archaeologists, were determined by atomic absorption and flame emission techniques.