Periodic-acid is an oxidizer. The reaction of periodic-acid oxidizes the vicinal diols in some sugars such as glycogen, glycoproteins, glycolipids and mucins, usually breaking up the bond between adjacent carbons and creating a pair of aldehydes at the two free tips of each broken monosaccharide ring. The exposed aldehydes can be stained by magenta and generate red to purple red complex, which is a position mark. 

Usage:

1 Deparaffinize and rehydrate by immersing the slides through the following:

a. Xylene: two washes 20 minutes each

b. 100% alcohol: two washes for 5 minutes

c. 75% alcohol: wash for 5 minutes

d. Wash briefly in tap water

2 Periodic-acid stain

Immerse slides in periodic-acid solution for 15 min, wash in tap water and twice in distilled water.

3 Schiff stain

Stain slides in Schiff reagent for 30 min and keep in dark, followed by washing in running tap water for 5 min.

4 Hematoxylin stain

Rinse slides in hematoxylin solution for 1-3 min, wash in tap water. Differentiate in 1% hydrochloric-acid for a few second, wash in tap water. Bluing in 0.2%ammonia water, then wash in tap water.

5 Dehydrate and Mount

Dehydrate slides in 3 changes of absolute alcohol for 5 min each. Clear in 3 changes of xylene, 5 min each. Mount with resin mounting medium.

6 Microscopy examination and analysis

Staining result:

Purple red for collagen, goblet cell, fungus, plant starch granule and cell wall. Blue for nuclei.

Storage and transportation: The whole set of reagents can be stored at 4ºC and protected from light. Among them, PAS staining solution B and PAS staining solution C can be stored at room temperature, and the validity period is 12 months.
 

1 The periodic-acid solution should be stored in 4ºC

2 The Schiff reagent should be stored at 4ºC avoiding light and reach its room temperature before use. The Schiff reagent can be recycled and reused for many times. When it turns pink, it is unusable.

3 The staining time of Schiff reagent depends on room temperature. Shorten the staining time when room temperature is high (e.g. in summer), and extend it to about 60 min when room temperature is low (e.g. in winter).