Dynamic SIMS analysis of cryo-prepared biological and geological specimens

The modification of a dynamic magnetic sector secondary ion mass spectrometry (SIMS) instrument to permit the analysis of frozen biological and geological samples is described. The SIMS instrument used for this study combines SIMS analysis with the generation of ion-induced secondary electron images, allowing direct superposition of the SIMS image onto the image of cellular structures. Secondary ion maps have been acquired with sub-micron resolution, permitting the characterisation of sub-cellular elemental distributions in plant cells and human fibroblast cells, as well as the distribution of chemical impurities at grain boundaries in polar ice samples. This cryo-preparation technique clearly extends the applicability of SIMS analysis to a wide range of samples.