From: Brandon S. Chance <bchance**At_Symbol_Here**PRINCETON.EDU>
Subject: Re: [DCHAS-L] piranha solution
Date: Wed, 20 Aug 2014 14:51:59 +0000
Reply-To: DCHAS-L <DCHAS-L**At_Symbol_Here**MED.CORNELL.EDU>
Message-ID: D01A2CB4.2DCAF%bchance**At_Symbol_Here**


Virtually every piranha acid SOP I have read recommends adding the peroxide to the acid and NOT the other way around.  There is a larger volume of acid in any of the standard piranha preparations and the concentration of peroxide should not be exceed the recommended ratios (3:1, 5:1, 7:1 sulfuric acid:hydrogen peroxide).  It is recommended to add the peroxide slowly to prevent boiling.  This is a very exothermic reaction.  Some universities report that if concentrations of peroxides exceed 50%, violent explosions can occur.  

Brandon S. Chance, M.S., CCHO

Program Manager, Chemical Safety

Environmental Health and Safety

Princeton University

262 Alexander Street

Princeton, NJ 08540

609-258-7882 (office)

609-955-1289 (mobile)

609-258-1804 (fax)

"… our job in safety is to make the task happen, SAFELY; not to interfere with the work…" Neal Langerman

From: Wayne Phan <Wayne.Phan**At_Symbol_Here**POMONA.EDU>
Reply-To: DCHAS-L <DCHAS-L**At_Symbol_Here**MED.CORNELL.EDU>
Date: Tuesday, August 19, 2014 at 5:32 PM
Subject: [DCHAS-L] piranha solution

When preparing piranha solution, do we add acid to the peroxide or the peroxide to the acid.  I see different opinions on this.  What is the standard practice?





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