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7.19.2 Deactivation Procedures

Deactivation is managed by breaking the chemical bonds of ethidium bromide. Within a laboratory setting, these bonds can be broken in several ways, including oxidization and UV radiation. Deactivation of ethidium bromide waste materials must be incorporated as a last step in the research protocol. The methods described here oxidize the mutagen to remove the risk.

Household Bleach

The following is from Network News, Volume 8 No. 2, September 1994. Network News is a tri-annual publication of the ACS Department of Government Relations and Science Policy's Office of Legislative and Regulatory Programs. Margaret-Ann Armour is a professor in the Department of Chemistry at the University of Alberta.

Begin by wearing the proper personal protective equipment such as a lab coat, safety glasses, and gloves. To convert ethidium bromide (EtBr) to the physiologically inactive product 2-carboxybenzophenone, stir a solution of 34 mg of ethidium bromide in 100 mL of water (at room temperature) with 300 mL of household bleach for 2 hours. When ethidium bromide solutions of this dilute concentration are used, the product solution does not show excess mutagenicity over standards in the Ames test.

Note: To extrapolate this method to various concentrations of ethidium bromide, you want to add ~ 10mL of household bleach for every mg of ethidium bromide.

You should check the extent of completion of this process with a Ultra-Violet (UV) lamp. EtBr glows bright orange under UV. If you see no orange fluorescence under the correct wavelength of UV in the detoxified material, then it has effectively been degraded.