From Nov. 20, 1978:
SIR: We would like to alert persons to possible hazards involved with the rather common laboratory procedure of dissolving electrophoresis polyacrylamide gels with hydrogen peroxide, in order to measure radioactive species by scintillation counting.
Recently a very violent explosion occurred in one of our laboratories which caused complete destruction of a hood and moved a cinder-block wall located 30 feet from the blast. Kick-out panels and glass were blown out of the laboratory and chemicals on shelves in the adjacent laboratory were knocked to the floor. Fortunately the blast occurred when the labs were vacant, or otherwise severe injury or loss of life would certainly have occurred to personnel.
The blast apparently occurred due to the formation of explosive peroxides formed from the solubilization of polyacrylamide gels and subsequent counting procedures. The procedure used was basically the following: Polyacrylamide gels (1 cm2) were dissolved with the addition of 0.6 ml of 30% H202, and the resulting solution was added to a scintillation cocktail consisting of a 1:1 mixture of toluene and 2-ethoxyethanol along with scintillation fluors. After the samples were counted for 14C, the contents of all scintillation vials were pooled and concentrated over low heat on a hot plate in the hood. Eventually the radiological safety officer was to dispose of the material. Material had been accumulating in the hood for three to four weeks.
Addition of hydrogen peroxide to the polyacrylamide gels could result in the formation of peracids azo- or nitro-compounds. This mixture was then added to the toluene-ethoxyethanol cocktail, and hydrogen peroxide not used in solubilization of the gel could form explosive adducts with the ether. Tests of a commercial cocktail mixture showed that peroxides were present even before the hydrogen peroxide was added.
The procedure used for dissolving the gels is used by many laboratories and had been used for three years in our labs without incidence. We recommend that either alternate methods be used to solubilize the gels or that the peroxides be immediately destroyed after scintillation counting.
'Dennis W. Darnall, Professor of Chemistry, New Mexico State University, Las Cruces
(further discussion of the mechanism of the explosion in the blog post)
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