Hi all,

I am wondering if there is a colored dye that could be placed in certain liquid histology reagents that come in direct contact with tissue, but would not obstructively bind to it (that is, not interfere with Cresyl Violet or immuno staining of specific proteins). Specifically, after hearing horror stories of forgetting to add azide to PBS-Az (a simple but potentially devastating mistake for bulk tissue storage), I am considering making stock azide solution tinted with some color, so that one can tell when it has or has not been added to PBS. I'm reading that food coloring, for example, binds to proteins, and just wouldn't want to confound any further protein staining of sections stored in tinted PBS-Az (although perhaps if the concentration was low enough it wouldn't be significant).

Let me know if you have tips. Otherwise, may test myself and follow up. Thanks so much!