Published online by Cambridge University Press: 06 March 2019
Methods have been developed for autopsy tissue analysis using a proton-induced X-ray emission (PIXE) system optimized for thin sample analysis. The system uses 2 MeV protons, thus limiting sample thickness to several milligrams per square centimeter. Calibration was accomplished with standard solutions spotted onto Nuclepore filters, which were subsequently irradiated in a uniform proton flux. X-ray yields measured with a Si (Li) detector were corrected for proton energy loss in the filter matrix as well as X-ray attenuation. Corrections for proton energy loss were determined from empirical parameters relating proton energy to X-ray cross sections. Typical filter thickness and penetration of the sample solution into the filter matrix were measured allowing calculation of proton energy attenuation and X-ray absorption corrections. The method was used in routine analyses for sixteen elements in seven types of human tissue. Accuracy was evaluated with standard reference materials and atomic absorption analyses.