I've worked in an industrial lab that used phytic acid as a substrate for an enzymatic assay. Historically there are many issues obtaining phytic acid that is acceptable.

The color of the phytic acid product is due to many things - purity and metallic contaminants, production process, source material, etc. Also, what form of phytic acid is in the product.

Generally, phytic acid as purchased from Sigma doesn't degrade unless it is kept in very poor conditions. We had bottles of the stuff that could sit on a shelf or in a freezer for years without any adverse effects being seen in testing. We did notice when the formulation had changed, either due to switching from rice to corn as the source material or where the product was produced. There have been several shortages and backorder situations over the past decade where the products were not acceptable for assay use due to the inherent mineral contamination from the source or the plant where the phytic acid was produced.

Thank you,
 
JENNIFER JENSEN
Lab Materials Manager & Environmental Compliance Officer 
Central College Science Departments
812 University St. | Campus Box 083 | Pella, Iowa 50219
 
jensenj**At_Symbol_Here**central.edu | www.central.edu
Office: 641.628.5207 | Stockroom: 641.628.7187
-----Original Message-----
From: ACS Division of Chemical Health and Safety [mailto:DCHAS-L**At_Symbol_Here**Princeton.EDU] On Behalf Of DCHAS Membership Chair
Sent: Thursday, August 20, 2020 8:29 AM
To: DCHAS-L**At_Symbol_Here**Princeton.EDU
Subject: [DCHAS-L] wondering where the yellow went

From: Monona Rossol <actsnyc**At_Symbol_Here**cs.com>
Re: wondering where the yellow went

Phytic acid is described in the literature as a yellow to brownish liquid.  There is a thread on the American Institute for Conservation's (AIC) forum about art conservators switching away from Sigma's phytic acid more brownish acid to another provider's whose phytic acid is pale yellow.  The assumption is the Sigma product has "degraded."

Danged if I have a clue.  I just know as vegetarian, I eat more of it than they do.  Does anyone out there have a clue what this reagent color difference actually is? 

Monona

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