Safe plunge freezing

Publication date: Available online 1 December 2018Source: Journal of Chemical Health and SafetyAuthor(s): Robert C. Klein, Brent Lewchik, Simon WhitePlunge freezing is a laboratory technique used to flash freeze biological specimens for imaging by cryo-electron microscopy. Common cryogenic liquids such as liquid nitrogen and helium are ill-suited for this process as they result in ice crystal contamination. Liquefied short-chain alkanes are used instead, with ethane generally considered the premier reagent. While liquid ethane has similar hazards to other cryogenic liquids (e.g., asphyxiation, frostbite), it is also a highly flammable gas.Airborne concentrations of ethane gas were characterized during manual handling, dispensing, and use of this cryogen in a commercial plunge freezing device. Measurements made across these activities suggest that the routine use of small quantities of liquid ethane in plunge freezing is unlikely to generate an explosive atmosphere in laboratory chemical hood exhaust or at the open bench. Small-volume spills did not result in a hazardous atmosphere, and the purposeful complete opening of the second stage gas cylinder regulator (identified as the probable worst-case accident scenario) resulted in maximum levels of only about 11% of the lower explosive limit (LEL) in laboratory chemical hood exhaust.
Source: Journal of Chemical Health and Safety - Category: Chemistry Source Type: research