How do I ensure that specimens are well frozen? FAQ Report There are a variety of methods that can be successfully used for freezing various types of specimens and the best techniques are often determined by trial and error. Here are two basic methods that can be used to obtain good specimen freezing: Using cryogens such as isopentane and solid carbon dioxide. An excellent freezing technique is using a combination of these two cryogens. Place 50 mL of Isopentane in a glass (or polypropylene) beaker and place it into a mound of solid carbon dioxide, CO2 pellets, so that the pellets surround and are in direct contact with the beaker. Allow the Isopentane to stabilize, the resulting temperature will be approximately -80°C. Trim your sample to a suitable size for sectioning, try to use samples that are not thicker than 4.0 mm, (a recommended sample size for cryosectioning is 20 mm x 20 mm x 4.0 mm) and put the sample into the Isopentane and allow to freeze. While the sample is freezing place a clean specimen disc on the freezing shelf of the cryostat. Remove the sample from the Isopentane and mount onto the specimen disc with a small volume of cryocompound. Allow the specimen to equilibrate to chamber temperature, as it will be too cold to section immediately. Using a rapid freezing system mounted in the cryostat. The freezing shelf of the cryostat is an alternate method of freezing especially if the freezing shelf is fitted with a Peltier element. A Peltier element is a thermoelectric device that allows “heat” from the sample to be reduced at a very fast rate and thus freeze rapidly. To use the Peltier element, or freezing shelf, trim the specimen to a suitable size, with a maximum thickness of 4.0 mm. Turn on the Peltier element. Select a suitable specimen disc and mount the specimen onto the disc with a small volume of cryocompound. Allow the specimen to equilibrate to chamber temperature as it will be too cold to section immediately. Another excellent method of freezing is using the Precision Cryoembedding System. Please visit http://www.pathologyinnovations.com/ for details.