[Histonet] Schiff mystery

[Lee & Peggy Wenk]

Need the help of the Histonet chemistry gurus.

This has happened the last 2 times the students and I made up Schiff. Two
different set of students.

We make up the Schiff, and use it the next day, and it works correctly
(stains the glycogen in liver and neutral mucins in intestine a bright
magenta). Store in refrig. 1 week later, when we go to stain fungus with
PAS, the Schiff doesn't work. Try the same liver and small intestine
controls. Doesn't work at all. No magenta, no pink, nothing on the slides.

When going into the water rinse after Schiff, the water turns pink with the
newly made Schiff, but 1 week later, there is no color change in the water
rinse.

When we make up the Schiff, we show the students the Schiff quality
assessment, where we put a few drops of formaldehyde in it, and the Schiff
changes to purple immediately. Works great newly made. One week later, when
we can't get the Schiff to stain, there is no color change with
formaldehyde. None.

It is the same procedure we've been using for years to make up the Schiff.
It is the same procedure our histology lab uses. Their Shiff lasts for
months. Ours last for a few days.

I think it might be one of our reagents is going bad. Histology lab has
their own reagents, the School has our own. 
- The basic fuchsin is OK, as the Kinyoun works great.
- The hydrochloric acid was taken from histology, so I'm guessing it's OK.
- The charcoal is fairly new. Could that be the problem? Why?
- We are using sodium metabisulfite, not sodium sulfite or sulfate. At least
that's what the bottle says. Does this break down and go bad?

Need all the help we can get. This is spooky, Halloween or no Halloween.

Peggy Wenk, HTL(ASCP)SLS
Schools of Histotechnology
Beaumont Hospital
Royal Oak, MI 48073