Recently our lab has run into some problems with our acid phosphatase
procedure on 8 micron sections of frozen muscle samples.  We are
experiencing faint/minimal staining or total loss of staining on sites
of enzyme activity that the red azo dye should be binding to.  We have
run this procedure for many years without a problem, obtained beautiful
results and "bingo" it just stopped working for us.

I have:
1. Remade/rechecked all solutions
2. Used new Napthol AS-BI Phosphate from 2 sources
3. Used new dimethylformamide from 2 sources
4. Used new pararosaniline chloride from different sources
5. Checked and rechecked the pH meter
6. Checked and rechecked oven temperatures
7. Used several procedures-all with unsatisfactory results
8. Had several techs run the variety of procedures-all unsatisfactory
results

What am I missing? It could be something really obvious and I just
cannot see it! I would appreciate some input on this woe of mine!
Thanks!

Jean Mitchell, BS, HT
University of Wisconsin Hospital & Clinics
Department of Neurology, Neuromuscular Laboratory
Madison, WI