IONIZATION PROBABILITY VARIATIONS DUE TO MATRIX IN ION MICROSCOPIC ANALYSIS OF PLASTIC-EMBEDDED AND ASHED BIOLOGICAL SPECIMENS

Matrix effects on ionization probabilities have been investigated for ion imaging of plastic-embedded and ashed biological thin sections. Practical ion yield ( tau ) maps were constructed by using Be, introduced by quantitative ion implantation, as a reference element. The tau maps show that variations in Be signal are less than 1% in plastic-embedded tissue and of the order of a few percent in ashed tissue. These results, when extended to physiologically important elements, indicate that matrix effects are of relatively small importance in quantitative analyses of these samples. Specific methods for the conversion of ion intensities to elemental concentration for each sample type are discussed.