Eliminating Mercury Thermometers from the Lab

Abstract

This brief laboratory safety note describes how electronic cooking thermometers can be used to replace standard mercury thermometers in the undergraduate organic chemistry lab. Various factors, including safety, cost, and ease of use, were considered. The stainless steel thermometer probe connected to a LCD display unit adequately serves multiple purposes in the organic lab while eliminating the hazards associated with the use of mercury thermometers.

Mercury Thermometer Replacements in Chemistry Laboratories

“…The thermometer is immersed to the depth that is noted on the liquid column to accurately measure the temperature with a partial immersion thermometer (11). Although the author of a recent article on mercury thermometer replacements found the accuracy of the Enviro-Safe thermometer to be too dependent on the degree of immersion, his study was based upon the use of a total immersion Enviro-Safe thermometer (12). The 76-mm depth partial immersion model has proven to be ideal for our needs in the academic organic chemistry laboratories.…”

A Simple, Inexpensive, Mercury-Free Bubbler Apparatus

“…Closer to our own institution, the state of Minnesota has been at the forefront of state-based regulation of mercury via its own ongoing reduction plan, the Mercury Total Maximum Daily Load, initiated in 2007 . In the laboratory setting, replacement of mercury thermometers was the primary target given their ubiquity and heavy use. − Mercury-based bubblers for Schlenk lines are a common laboratory application of mercury that has lingered as no easily implemented, universal, and comparable replacement has arisen. Our developed apparatus seeks to eliminate the need for mercury for this purpose while providing an equal, if not superior, replacement for the mercury bubbler design itself.…”

“…The original design for a mercury bubbler, reported in this Journal by Bissey, has seen widespread use for decades. 9 Replacing mercury (ρ = 13.69 g/cm 3 ) with mineral oil (ρ = 0.83 g/cm 3 ) is not unprecedented but comes with the obvious drawback of significantly reduced density and thus reduced pressure. 10 Since the introduction of the Bissey valve, a few alternative designs have surfaced to allow for the use of oil as an alternative while still maintaining the integrity of the air-free system, with the Lafler design being one of the best examples.…”

An Accessible Mercury-Free Vacuum Schlenk Line for Air-Free Techniques

“…The impetus for this contribution is the increased attention to the hazards of mercury in the laboratory. This Journal has published articles that describe the use of the mercury bubbler to introduce inert gases to reactions that must be protected from the atmosphere, and safety notes to provide ways to eliminate or protect the lab from mercury in thermometers and McLeod gauges. − Our institution has initiated a mercury reduction policy. The driving force for this policy, The Great Lakes Binational Toxics Strategy, signed by Canada and the United States in April 1997, set a goal of virtual elimination of mercury with significant measurable results by 2006, and it is a policy that continues to be implemented .…”