Decontamination of Ethidium Bromide Solutions and Surfaces

 

WARNING: EtBr is toxic and mutagenic. Hypophosphorus and its solutions are\corrosive. Decontamination solution gives off a small amount of nitrogendioxide, a toxic gas, when initially mixed.

Laboratory Safety Practices and Equipment:

-	Prepare decontamination solution in the fume hood.
-	Wear two layers of gloves, lab coat and safety glasses.
-	Turn off electrical equipment before decontamination.

Preparation of Decontamination Solution:

Prepare fresh solution on day of use. Add hypophosphorus acid to an aqueous solution of sodium nitrite:

	1 litre	2 litres	3 litres
Sodium nitrite	13.6g	27.2g	40.8g
Hypophosphorus acid	67ml	134ml	200ml

Decontamination of EtBr Waste:

-	Procedure has been validated for EtBr solutions of less than 0.5mg/ml in water, TBE buffer, MOPS buffer and CsCl gradients. For solutions greater than 0.5 mg/ml, dilute to 0.5 mg/ml with water.
-	Liquid waste: Add 1 part decontamination solution to 3 parts EtBr solution (25%).
-	Solid waste: Ensure that all waste is submerged in the decontamination solution and in contact with it.
-	Mix and hold for 20 hours.
-	Neutralise with sodium bicarbonate and discard as non-hazardous aqueous waste for solutions. For solids, seal in plastic bags and discard.

References:

1. Lunn, G. and Sansone, E.B. (1987) Ethidium bromide: destruction and decontamination of solutions. Anal. Biochem 162 :453.
2. Lunn, G. and Sansone, E.B. (1989) Decontamination of ethidium bromide spills. Appl Ind Hyg 4 :234.