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Benzoylation for the Periodic Acid-Schiff Reaction


For the Periodic Acid-Schiff Reaction

This procedure is used in the Periodic Acid-Schiff (PAS) reaction to block hydroxyl and amino groups. It does this by forming esters with them. As a consequence, some carbohydrates fail to react with the Schiff’s reagent. This may be used as a means of identifying them, particularly if done in conjunction with other blocking procedures.


Benzoyl chloride2mL
Pyridine, anhydrous38mL


Place dewaxed sections into the solution at the temperature specified for the time given.

Cartilage58°C6 hoursAlmost complete
Glycogen58°C6 hoursComplete
Epithelial mucin58°C6 hoursComplete

Safety Note

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


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