Diffusible ion localization by ion microscopy: a comparison of chemically prepared and fast-frozen, freeze-dried, unfixed liver sections

Abstract

The necessity of low temperature preparative procedures for diffusible ion localization using the ion microscope was established with rat liver as the test material. Using conventional fixation procedures, significant ion loss and redistribution were observed which exceeded the 1 .mu.m lateral resolution of the direct imaging ion microanalyzer. The compositional morphology evidenced in chemically prepared vs. fast-frozen, freeze-dried, unfixed material was compared and evaluated in terms of ion retention, ion redistribution and morphological integrity. A mass spectral analysis of both preparations was presented and discussed with regard to spectal interferences and elemental sensitivities. Ion images of Na and K were recorded for chemically prepared liver sections and compared with the ion distributions obtained for unfixed, fast-frozen, freeze-dried 1 .mu.m thick sections. The magnitude of ion loss during preparation of samples removed at different stages in the course of chemical processing was determined by atomic absorption and flame emission spectrophotometry.