Secondary ion emission and images from a biologic matrix

Abstract

Secondary ion mass spectra and images were obtained from organic compounds deposited on gold and 30–50 μm thick biologic tissue substrates. Analyte solutions were prepared from acetylcholine chloride, choline chloride, and methylphenylpyridinium (MPP +) iodide. Tandem mass spectrometry (MS/MS) was used to distinguish secondary ions characteristic of the analyte from secondary ions characteristic of the tissue itself. Effects of primary ion damage appear similar regardless of substrate. Samples of choline chloride deposited on a gold substrate are exceptional; secondary ion emission from such samples appeared unaffected by primary ion dose. Emission of acetylcholine secondary ions was found to decay with a rate independent of primary ion dose, but dependent on the substrate. These results show that the distribution of organic compounds can be mapped from biologic tissue under conditions of static SIMS, but matrix effects and chemical noise must be considered.