PIXE AND NAA ANALYSIS OF MERCURY IN A STANDARD SET OF SOUTHERN MAGNOLIA WOOD SAMPLES

Abstract

Several southern magnolia (magnolia grandiflora) tree samples, with known concentrations of mercury, were analyzed using particle induced x-ray emission (PIXE) and neutron activation analysis (NAA). Results from the PIXE measurements indicate that the average mercury absorption percentage was found to be 85 ± 4%. The distribution of mercury was found to be reasonably homogeneous over the sample surface. However, small variations in mercury concentration are most likely caused by the structure of cellulose in the wood. Mercury in the samples appears to be stable to a total integrated charge of 10 μC. Three mercury L-shell x-rays are easily observed in the resulting PIXE spectrum. Using PIXE, the mercury detection limit was calculated to be approximately 1 ppm. With one exception, the measured NAA mercury concentrations were larger than the corresponding mass-based values. The NAA mercury detection limit for the southern magnolia samples was estimated to be about 0.017 ppm (17 ppb).