The recommendation for evacuated cold storage is primarily to protect the (probably costly) biological product from water-mediated chemical degradation and/or denaturation.   The purchased quantities of such products is typically in the 10 to 500 mg range.  The mass percentage of the product that is actually chemically derivatized picric acid is VERY low relative the amount of LARGE protein molecule.  For each 10 - 500 mg of protein an overestimate of 1% picric acid in the product means the presence of 0.1 to 5 mg of picric acid in 10 - 500 mg of product.

Because the picric small acid molecules are covalently bound to complex large protein molecules,  individual picric acid molecules would not be in a physical configuration that allows their formation of "picric acid crystals." 

From a chemist's perspective, the electronic configuration of picric acid that is responsible for its explosive/shock sensitive characteristics are most likely favorably modified by covalent reaction with the large protein molecule.

Even if not convinced by any of the above, the explosion of a few mg of picric acid would not be a destructive event.

David Haugen (retired)

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From: "Ralph B Stuart" <rstuart**At_Symbol_Here**CORNELL.EDU>
To: DCHAS-L**At_Symbol_Here**MED.CORNELL.EDU
Sent: Friday, January 27, 2012 11:32:28 AM
Subject: [DCHAS-L] Conjugated picric acid hazards?

Our biosafety officer is reviewing work that includes the use of a couple of forms of conjugated picric acid (TNP-AECM-FICOLL and TNP-Chicken Gamma Gobulin). The MSDS's are pretty skimpy, but include the advice to store it in a dessicated environment. This is counterintuitive to us and the MSDS's are vague enough about the material's reactivity ("Risk of explosion by mechanical impact: Not Available") that we'd like confirmation from people with more experience in the use of this material that picric acid's explosivity is not a concern in this application.

Does anyone on the list have more information about this concern?

Thanks for any help with this.

- Ralph

Ralph Stuart CIH
Laboratory Ventilation Specialist
Department of Environmental Health and Safety
Cornell University

rstuart**At_Symbol_Here**cornell.edu