Applicability of a high pressure digestion technique to the analysis of sediment and soil samples by inductively coupled plasma-mass spectrometry

As inductively coupled plasma-mass spectrometry (ICP-MS) expands its role in earth sciences, the concern about incomplete sample digestion remains. To address this problem, the use of high pressure dissolution was examined. High pressure digestion vessels (HPDVs) were fabricated and their use was compared with the existing method used at Memorial University of Newfoundland that utilizes screw top PTFE (STT) jars for digesting reference materials (RMs). ICP-MS analysis of solutions demonstrated more complete digestion of three marine sediment RMs, indicated by higher Y, Zr, Nb, heavy rare-earth element (HREE), Hf, and U concentrations when the HPDV was used. The results indicate better decomposition of resistant minerals, especially zircons that were likely in high abundance in the sediments. To evaluate its suitability to real samples, the method was applied to the ICP-MS analysis of sediment and soil samples from Cebu, Philippines. Good correlation for Nb and Pb, among other elements, was shown by the results from ICP-MS and X-ray fluorescence spectrometry. Barium recovery was relatively low for ICP-MS, possibly due to particle size difference. Mapping of data showed that the distribution of some elements, particularly the lighter rare-earth elements (REEs), in the soils corresponds to local geology; however, for others such as Zr, Nb, and Pb, results seem to correlate with anthropogenic activity.