Chemical destruction Methods for Ethidium Bromide in Solution:
N.B. all such
operations should be conducted in a fume hood since chlorine gas
or nitrogen dioxide may be evolved.
1. Hypophosphorous
acid + sodium nitrite treatment: (reference 2)
- dilute
EB solution to less than 0.5 mg/mL
- for a volume
of less than 100mL (50 mg EB),
- add 20
mL of 5% (w/v) hypophosphorous acid solution (mixture must be
< pH 3),
- add 12
mL of 0.5M sodium nitrite solution,
- stir at
room temperaure for 20h,
- neutralize
with sodium carbonate and flush down the drain with water.
Comments
Method 1:
- method
expected to leave less than 0.2% of original EB concentration
(measured spectroscopically) and less than 0.6% of original
mutagenic activity.
- prepare
hypophosphorous acid and sodium nitrite solutions fresh each
day
- pH must
be less than 3 for destruction to occur
- similar
results if EB is dissolved in water, 40 mM MOPS or 90 mM TRIS-boric
acid-EDTA (TBE) buffer
2. Potassium
permanganate + HCl digestion: (reference 2, 3)
- dilute
EB sample to less than 0.5 mg/mL
- for a solution
volume of less than 100mL (50 mg EB)
- add 100
mL of 0.5M potassium permanganate solution
- add 100
mL of 2.5M HCl (or 100 mL of 6M H2SO4)
- stir for
20h at room temperature
- neutralize
with sodium hydroxide (or sodium carbonate).
- potassium
permanganate is a strong oxidizer which should be reduced by
adding a saturated solution of sodium bisufite
(HNaO3S, mw104.1, about 30 g / 100 mL)
until the mixture is colorless.
- flush
the mixture down the drain with water.
Comments
Method 2:
- expect
this method to leave less than 0.2% of original EB concentration
and less than 0.03% of original mutagenic activity.
- this method
may be effective with EB concentrations greater than 0.5 mg/mL
but it is safer to keep dilute to ensure successful destruction
- may use
sulphuric acid instead of hydrochloric to avoid chlorine vapors
|
