COMPARISON OF LASER MICROPROBE MASS-SPECTROMETRY (LMMS) AND MICRO PARTICLE-INDUCED X-RAY-EMISSION (MICRO-PIXE) FOR THE ANALYSIS OF SENILE PLAQUES IN ALZHEIMERS-DISEASE - A PRELIMINARY-STUDY

Results of micro-PIXE analysis of senile plaques (SP) in Alzheimer's d isease (AD) brain have been utilized to independently confirm levels o f iron (Fe) as measured by LMMS in adjacent brain sections. LMMS conce ntrations were calculated based on the preparation and analysis of an iron calibration curve prepared in our laboratory. The LMMS standards consist of iron cis-dicyclohexano-18-crown-6 ether coordination comple xes dissolved in Spurr's low viscosity embedding medium. To our knowle dge, this is the first report of the use of micro-PIXE, with its spati al resolution and detection limits comparable to that of LMMS, in the validation of LMMS results. The agreement observed between results obt ained for Fe by micro-PIXE and LMMS indicates that the use of our LMMS standards, at least in the case of Fe, yields accurate results.