On Wed, 24 Mar 1999, Rita wrote:

> My next question is:  The only Sirius Red I could find in a catalogue
> is Direct Red 80 from Aldrich.  (Sirius Red is in parenthesis)  My
> procedure calls for Sirius Red F3BA.  Is this the same thing? 

    Yes. C.I. 35780 Direct red 80 = sirius red F3B

> Also the
> dye content of the Direct Red 80 is ~30%.  Does this have any bearing on
> the matter? 

    Treat the powder as if it were 100% when following the
    instructions to make a 0.1% (or whatever) solution.
    All dyes are mixed with inert fillers etc. Sirius red
    is not yet one of the dyes certified by the Biological
    Stain Commission, so you have to rely on your supplier
    for a decent product. Aldrich's dyes are usually OK.

> And also does anyone know where I can order Sirius Red
> F3BA?  
        The stuff I use was bought years (?15) ago from
        BDH as one of their "Gurr" line of products. It's
        called sirius red F3B on the label, and there's a
        Product number 34149; no C.I. number or name. It
        performs well. The solutions in picric acid keep
        for at least 3 years (probably longer) without
        any loss of potency. I have used it only for collagen,
        not amyloid.

     Don't confuse sirius red F3B with sirius red 4B (C.I.
     28160, Direct red 81), which has also been used as a
     stain. It might behave simuilarly, but then again it
     might not, because it's a different substance with
     considerably smaller molecules than C.I. 35780.

  Hope this helps.
                    John Kiernan
                    London, Canada

 John A. Kiernan,
 Department of Anatomy & Cell Biology,
 The University of Western Ontario,
 LONDON,  Canada  N6A 5C1