Soil sample preparation for PIXE analysis

Since the Great East Japan Earthquake on 11 March 2011, we have seen a rapid increase of requests for soil analysis by PIXE. In the Nishina Memorial Cyclotron Center (NMCC), a powdered internal standard method with palladium on carbon powder has been adopted for soil sample preparation. However, the method can be heavily laborious when many samples need to be handled in a limited time. Here, we report an alternative to the method which takes a standard in the liquid form with a few drops of acetone to be homogenized with soil sample in an agate mortar. The applicability of the moist method was examined using some standard reference materials by comparing the analyzed results with those from the conventional method and with the certified values. The results were generally satisfactory, although further examination is needed to improve the accuracy and reliability of the new method.