External proton beam for X-ray emission analysis of human blood plasma

An external beam facility has been developed for proton induced X-ray emission (PIXE) studies of human plasma and other biological material. A new exit foil support system and a new simplified sample preparation method were used. Strong peaks for iron, copper, zinc and bromine were seen in plasma from both normal subjects and patients with primary biliary cirrhosis or other liver diseases and their absolute concentrations were determined. Detection limits were approximately 0.15 ppm allowing measurements to be made in <15 min using only 0.8 ml of plasma. The range of values in normals was consistent with previous studies. Significantly elevated Cu and Zn levels and Zn/Cu ratios were found in the patients. The significance of these results and the usefulness of the method in trace element analysis is discussed. (author)