So, if I am not mistaken 0.5 ug/ml is 0.197 mols per liter EtBr
this is an abstract from
Ethidium bromide: destruction and decontamination of solutions. (Armour Method ( Lunn, G.and E. Sansone)
Ethidium bromide in water, TBE buffer, Mops buffer, and cesium chloride solution may be completely degraded by reaction with sodium nitrite and hypophosphorous acid. Only non-mutagenic reaction mixtures were
produced. Destruction was greater than 99.8% in all cases; the limit of detection was 0.5 micrograms ethidium bromide per milliliter of solution. Ethidium bromide also may be removed completely from the above solutions by using Amberlite XAD-16 resin. The
limit of detection was 0.05 micrograms ethidium bromide per milliliter of solution (0.27 micrograms/ml when cesium chloride solution was used).
I haven't tested this next method but maybe follow this reaction at slight molar excess of the neutralizing reagents.
Lunn & Sansone Method: For each 100 ml of aqueous EtBr solution:
• Add 5% hypophosphorous acid.
• Add 12 ml of 0.5 M sodium nitrite.
• Stir briefly and let stand for 20 hours.
• Adjust pH to 7-9 using sodium hydroxide.
• Pour down drain with copious amounts of water.
From: ACS Division of Chemical Health and Safety <DCHAS-L**At_Symbol_Here**PRINCETON.EDU> on behalf of Penny Manisco <pmanisco**At_Symbol_Here**G.HMC.EDU>
Sent: Thursday, August 9, 2018 5:37 PM
Subject: [DCHAS-L] Dilute Ethidium Bromide Disposal in California
There seems to be varying opinion on how to dispose of very dilute solutions of ethidium bromide. The concentration in question is 0.5 micrograms/ml of buffer. By hazardous waste definition, this would not be considered a hazardous waste, but I believe
some of our California universities and colleges recommend filtration of the ethidium bromide before disposal at any concentration.
Any guidance would be very much appreciated.
Chemical Hygiene Officer
Harvey Mudd College
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