Authors:M. Deibel, S. Landsberger, D. Wu, and W. Ehmann
Copper (Cu) is an essential element and is incorporated in many biomolecules that are involved in protecting the brain from oxidative damage. Many brain regions strongly affected by neurodegene rative diseases are small. A sensitive nondestructive procedure to determine Cu is desirable to preserve samples for additional studies. Copper is not easily determined by instrumental neutron activation analysis (INAA) due to high activity levels produced by major abundance elements such as sodium (Na) and chlorine (Cl), which produce a high Compton background. An INAA method involving a short epithermal neutron irradiation and counting with a Compton suppression system was developed to determine Cu in brain, via 5.1-min66Cu. These short irradiation results are compared to those based on coincidence spectrometry of annihilation photons from positron emitting 12.7-h64Cu after a long irradiation.
Authors:M. Deibel, J. Savage, J. Robertson, W. Ehmann, and W. Markesbery
Chronic lead (Pb) intoxication has been linked to Alzheimer's disease (AD). Lead, like many heavy elements, tends to accumulate in bone. PIXE is a powerful analytical tool which permits the determination of Pb at the g/g level without requiring sample digestion. GFAAS is one of the most sensitive methods for the determination of Pb and is capable of determining ng/g levels in solution. For bone analyses by GFAAS, sample dissolution and a matrix modifier are required. Rib bone samples were analyzed for Pb by PIXE and GFAAS. IAEA Animal Bone (H-5) was used as a secondary standard for Pb with both methods to ensure accuracy. The range of Pb concentrations in human rib bone was 1.4–11.5 g/g for the trabecular surface by PIXE, 1.3–45 g/g for the cortical surface by PIXE, and 1.54–11.75 g/g for whole bone by GFAAS. No significant difference (p>0.05) was found for AD versus control for either surface or for whole bone.
Authors:W. Ehmann, B-F. Ni, D. Samudralwar, M. Deibel, and Z. Yu
Oxygen and fluorine have been simultaneously determined by 14-MeV INAA in samples containing boron. Both boron and fluorine can cause serious interferences in the determination of oxygen. The fluorine and boron interference corrections for oxygen determination have been determined to be 0.43±0.01 and 0.0832±0.0017 apparent g oxygen per g of fluorine and boron, respectively, for our system. Boron can be determined in the same sample by a second irradiation. Mutual interferences have been evaluated and the procedure has been applied to NIST SRM and several other compounds.