ASTM E1880-12(R2020) pdf free download

ASTM E1880-12(R2020) pdf free download.Standard Practice for Tissue Cryosection Analysis with SIMS
1. Scope
1.1 This practice provides the Secondary Ion Mass Spec- trometry (SIMS) analyst with a method for analyzing tissue cryosections in the imaging mode of the instrument. This practice is suitable for frozen-freeze-dried and frozen-hydrated cryosection analysis. 1.2 This practice does not describe methods for optimal freezing of the specimen for immobilizing diffusible chemical species in their native intracellular sites. 1.3 This practice does not describe methods for obtaining cryosections from a frozen specimen. 1.4 This practice is not suitable for any plastic embedded tissues. 1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appro- priate safety, health, and environmental practices and deter- mine the applicability ofregulatory limitations prior to use. 1.6 This international standard was developed in accor- dance with internationally recognized principles on standard- ization established in the Decision on Principles for the Development of International Standards, Guides and Recom- mendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
4. Summary of Practice
4.1 This practice describes a method for the analysis of tissue cryosections with SIMS. Tissue cryosections for SIMS analysis need to be mounted flat on an electrically conducting substrate. Cryosections should remain flat and adhere well to the substrate for SIMS analysis. This is achieved by pressing frozen cryosections into an indium substrate. Indium, being a malleable metal (Moh hardness = 1.2, Young’s modulus = 10.6 GPa), provides a “cushion” for pressing and holding the frozen cryosections flat for SIMS analysis. Indium substrates are prepared by pressing sheet indium onto a polished silicon wafer. An approximately 1 µm thick layer ofindium (99.999 % purity) is then vapor deposited on this surface. This top layer provides “fluffy” indium that helps in holding cryosections flat for SIMS analysis.
5. Significance and Use
5.1 Pressing cryosections flat onto a conducting substrate has been one of the most challenging problems in SIMS analysis of cryogenically prepared tissue specimens. Frozen cryosections often curl or peel off, or both, from the substrate during freeze-drying. The curling of cryosections results in an uneven sample surface for SIMS analysis. Furthermore, if freeze-dried cryosections are not attached tightly to the substrate, the impact of the primary ion beam may result in further curling and even dislodging of the cryosection from the substrate. These problems render SIMS analysis difficult, frustrating and time consuming. The use of indium as a substrate for pressing cryosections flat has provided a practical approach for analyzing cryogenically prepared tissue speci- mens (1). 4 5.2 The procedure described herein has been successfully used for SIMS imaging of calcium and magnesium transport and localization of anticancer drugs in animal models (2, 3, 4, 5). 5.3 The procedure described here is amenable to soft tissues of both animal and plant origin.
7. Procedure
7.1 Prepare the indium substrate by pressing sheet indium onto polished silicon wafer pieces of approximately 15 mm 2 to 25 mm 2 surface area, which can be irregularly shaped. A simple mechanical Pellet Press 5 can be used effectively for pressing for pressing sheet indium onto the surface of polished silicon wafer. Next, vapor deposit an approximately 1 µm thick layer ofhigh purity (99.999 %) indium onto the pressed indium sheet. The high purity of indium is emphasized only due to the fact that it should not impart any significant contamination to the sample. The vapor deposition can be achieved by vacuum- based processes such as evaporation from a heated filament or sputtering from an indium target. The indium substrates are now ready for use. 7.1.1 Chill an individual indium substrate by immersing it into liquid nitrogen prior to its use for pressing cryosections. Quickly transfer the indium substrate to the cryomicrotome and keep at the desired temperature of cryosectioning. Place a frozen tissue cryosection on the indium substrate and gently press by using a new chilled silicon piece. Make sure that the polished surface of the top silicon piece is used to press the cryosection onto indium substrate in order to avoid introducing the irregular topography of the rough silicon surface. Remove the top silicon piece by sliding it off using chilled tweezers. The pressed frozen cryosection on the indium substrate is now ready for frozen-hydrated analysis with a cold stage in the SIMS instrument. Alternatively, the pressed cryosection on the indium substrate can be freeze-dried by transferring the indium substrate to a freeze-drier.