Buffered Ethanol Fixative

In the recent Journal of Histochemistry & Cytochemistry (JHC) article by Perry et al.,¹ a fixative mixture designated “buffered ethanol 70%” (BE70) was judged best for preserving structural integrity, providing satisfactory immunostaining with three commonly used antibodies, and for allowing optimal extraction and amplification of nucleic acids. In the abstract, BE70 is called “phosphate buffered ethanol 70%.” The designation “buffered ethanol 70% (BE70)” is used also in the legends of Figures 1, 2, and 3. In the “Methods” section of the article, “70% ethanol + 0.5× phosphate-buffered saline . . . (EP)” most accurately corresponds to “phosphate buffered ethanol 70%,” but BE70 is identified as “70% ethanol + 1% glycerol + 0.5% glacial acetic acid + 0.5× PBS (EGAP; BE70).” The article does not provide enough information to allow other investigators to make the mixture that the authors favored for combined histological and biochemical preservation. If BE70 is a mixture in which acetic acid and a phosphate-buffered aqueous salt solution were mixed with ethanol, what is its approximate pH? This information is needed to define the composition of the BE70 fixative.