Isopentane Essay

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The results were similar to expected with liquid nitrogen and isopentane showing significantly better quality sections than the cold weight methods. This may be because the tissues rate of freezing was faster when immersed in the extremely cold liquids, compared to the -20degree weight. The surface area of tissue exposed to the cold was also more than that of the other methods.
Liquid nitrogen had the best results which was unexpected, however it should be noted that the quality of both the liquid nitrogen and isopentane sections was very similar. This may be put down to the small sample size of the project. The quality of the section was still poor in comparison to the formalin fixed section, but it ranked the best out of the freezing …show more content…

Isopentane is a hydrocarbon which is liquid at room temperature. It is extremely flammable and should be stored in a flammables cabinet. Isopentane does not boil when it comes in contact with tissue because it has a freezing point of −160°C and a boiling point of 28°C. (4) Tissue immersed in isopentane cools faster than those immersed in liquid nitrogen because there is no boiling effect. The actual method employed may have had a detrimental effect on the results. The isopentane was put into a 50ml beaker which only just fit the chuck and the liquid only just covered the surface of the tissue. This may have caused slower freezing of the tissue as the thin layer of isopentane was warmed through the tissue and room temperature. Some studies also suggest that movement while in the isopentane may give better quality results. This may be improved by using a larger beaker of isopentane, or using a smaller piece of tissue. An advantage of the isopentane over liquid nitrogen is that the tissue is frozen at approx. -165 degrees C compared to approx. -200 degrees C for liquid nitrogen. This means that the temperature difference between the cryostat and the tissue is not as great which reduces brittleness and the chance of the tissue

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