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de Tomasi’s Schiff Reagent

de Tomasi’s Formulation

Solution

MaterialAmount
Pararosanilin1g
Distilled water200mL
Potassium metabisulphite1g
Hydrochloric acid, 1N20mL
Activated charcoal (powder)2g

Preparation

  1. Heat the distilled water to boiling in an oversized Erlenmeyer flask.
  2. Take from the heat, and immediately add the dye. Be careful, as it foams.
  3. Shake well until the dye is dissolved.
  4. Cool to 50°C then add the hydrochloric acid.
  5. Shake well to dissolve.
  6. Cool to 25°C, and add the metabisulfite.
  7. Stopper well and store in the dark for one to two days.
  8. If not water clear, add activated charcoal and shake for about a minute.
  9. Filter the solution.
  10. Store at 0-5°C in a tightly stoppered bottle.

Notes

  • This solution differs from Feulgen & Rossenbeck’s Schiff reagent by specifying potassium metabisulfite as the source of sulfur dioxide instead of sodium bisulfite. However, according to the Merck Index, commercial sodium bisulfite is made predominantly of sodium metabisulfite, and for most purposes they are interchangeable.
  • The solution should be colorless or very pale amber. Brown solutions will often stain poorly. Usually these have been made from a batch of basic fuchsin containing too little pararosanilin.

Safety Note

Prior to handling any chemical, consult the Safety Data Sheet (SDS) for proper handling and safety precautions.

References

  1. Gray, Peter. (1954)
    The Microtomist’s Formulary and Guide.
    Originally published by: The Blakiston Co.
    Republished by: Robert E. Krieger Publishing Co.
    Citing:
    Feulgen and Rossenbeck, (1924)
    Zeitschrift für physikalische Chemie, v. 135, p. 203
    Leipzig.