Date: Mon, 20 Sep 2010 15:10:59 -0400
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From: "Johnson, Amy Carr" <amy_johnson**At_Symbol_Here**HARVARD.EDU>
Subject: Re: Peroxide Question
In-Reply-To: A<31CDAB47DAE8804085500A5498BBB79606E327CF**At_Symbol_Here**>

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Here is a link to the article from which the excerpt below was taken regarding safe levels of peroxides esh/cms/PDF/peroxides.pdf

“Kelly (7) reviewed the literature to determine the minimum hazardous concentration of peroxides in solution

with organic solvents. Peroxide concentration of 100 ppm has been widely used as a control point, but lacks

scientific justification and is probably based on the practical detection limit of the potassium iodide method. Kelly

reported great disparity (range 50-10,000 ppm as hydrogen peroxide) between various references. There was little

agreement between authors and none provided supporting data. The highest level (10,000 ppm) was found in a

National Safety Council publication (16). However, the NSC publication included no supporting references for the

latter statement or the NSC recommendation for administrative control value of 100 ppm.

The Material Safety Data Sheet for diethyl ether cautions against concentrating ether containing peroxide level

above 100 ppm (10). Presumably, instability and hazard increase with concentration such that at some point, the

solution spontaneously explodes. Kelly suggested that it is likely that the control concentration of 100ppm, in some

cases may be overly conservative by at least an order of magnitude. This may apply to the chemicals listed in Table

1-B unless the unstable materials are concentrated as result of solvent evaporation (7).

Kelly (7) stated that "theoretically, explosion should be impossible for most solutions of <1% peroxides."

However, to rationally establish a safe/hazard concentration is complicated by a number of factors. For example,

some of the liquid may remain on the threads and cap when peroxidized liquids are dispensed from glass containers

with screw-caps or with ground-glass stoppers. As the solvent evaporates, the peroxide can be concentrated to

dangerous levels within in the threads of the cap. Thus, a volatile solvent containing relatively low peroxide

contamination could explode because of peroxide concentration at the cap (3, 7). Dilute solutions of most

peroxidizable chemicals or solutions in solvents with low volatility (B.P. > 300 o C or V.P. <0.1 mm Hg at 20 o C)

usually do not pose a peroxide hazard and are not likely to concentrate. Thus, it is usually unnecessary to treat such

solutions as peroxide hazards (3, 5).

Some of the peroxidation products of the chemicals in Group A (Table 1) are less structurally stabile than those

in Group B. Thus even peroxide concentrations of less than 100 ppm should be considered very hazardous.

Unstabilized isopropyl ether can readily form highly unstable peroxides. Even low small concentrations produced

through solvent evaporation are very dangerous and may explode on shaking (33). The temperature and

concentration at which explosion of peroxides of isopropyl ether becomes probable has never been authoritatively

stated (20).”

Hope this helps-

From: DCHAS-L Discussion List [mailto:DCHAS-L**At_Symbol_Here**] On Behalf Of Bill Galdenzi
Sent: Friday, September 17, 2010 9:17 AM
To: DCHAS-L**At_Symbol_Here**LIST.UVM.EDU
Subject: [DCHAS-L] Peroxide Question


 < /o:p>

I have a question:   What concentration of peroxide do you folks use for your “acceptable” level?   What is the basis for this level?

 < /o:p>

Thanks for your help.

 < /o:p>

Bill Galdenzi

Environmenta l, Health, and Safety

Boehringer-I ngelheim Pharamceuticals

(203) 778-7759


 < /o:p>

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