Sulphite Rinses

Following the application of Schiff's reagent the excess must be removed somehow. In the past it was thought that rinsing with water could cause recolouration of the Schiff's reagent, which would then stain the tissue giving the appearance of positive staining. Sulphite rinses were developed to inhibit recolouration, by rinsing off Schiff's reagent with the solvent used to make it.

It is now known this is not necessary and, provided the sections do not stay in recoloured Schiff reagent for any length of time, non specific staining does not take place. It is common practice now to simply wash in running tap water for about 20 minutes.

Solution

Solution A			Solution B
Sodium metabisulphite	5 g		Hydrochloric acid, conc	1 mL
Distilled water	100 mL		Distilled water	1 L
Working solution			Note:
Solution A	1 volume		Potassium metabisulphite may also be used in Solution A.
Solution B	9 volumes
Make fresh daily.

 

Procedure

1. Place sections directly from Schiff's reagent into three changes of the working solution for about 2 minutes each.
2. Wash in running tap water for ten minutes.
3. Continue on with the stain.
4. Discard the solutions if they become distinctly red.

 

Reference

Lillie, R.D., (1954)
Histopathologic technique and practical histochemistry Ed.2
Blakiston, New York, USA.