ORGANIC SECONDARY ION IMAGING

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DESCRIPTION: (applicant's abstract) The objective of this research is development of secondary ion probe - ion trap mass spectrometry for determining the spatial and compositional distribution of targeted organic compounds in biological tissue. The particular targets of the current research period are glcycerophospholipids distributed in the brains of adult and neonatal rats. To accomplish these analyses, a secondary ionization (SI) microprobe will be integrated with an ion trap to create a SIMS/MS microprobe. The ion trap addition will permit high sensitivity in the measurement of ions of m/z 600-1000; this enhanced sensitivity is essential to mapping glycerophospholipids. This instrument makes it possible to generate ions from a particular location on the sample using a finely focused beam of the fullerene primary ions. Use of fullerene primary ions makes it possible to continually erode the sample surface without causing chemical alterations of the sample, at least as evident in successive SIMS spectra. This feature will make it possible to develop not only images based on the distribution of a single constituent, but maps of the different distributions of related compounds can be determined. Maps based upon phosphocholine secondary ion emission from adult rat brains will be developed initially, since similar maps have been generated using triple quadrupole mass spectrometry, and the distribution of phosphatidylcholine in adult rats is fixed.