This product has not been specifically qualified for antigen retrieval, however, it may be able to be qualified for use by the end user. A typical protocol using pepsin for antigen retrieval suggests the following stock and working solutions:
Pepsin Stock Solution (1% in 10mM HCl):
Pepsin ------------------------------------- 100 mg
10mM HCl (pH 2.0) ---------------------- 10 ml
Mix to dissolve. Store at -20 ºC
Pepsin Working Solution (0.5% in 5mM HCl):
Pepsin Stock Solution (0.5%) ------------ 1 ml
Distilled water ---------------------------- 1 ml
Mix well.
For antigen retrieval - cover sections with pepsin working solution and incubate for 10-20 minutes at 37 °C in humidified chamber (optimal incubation time may vary depending on tissue type and degree of fixation, and should be determined by user).
Product R2283 is a pepsin product qualified for antigen retrieval https://www.sigmaaldrich.com/product/sigma/r2283.
For more information, please see the following link: https://www.sigmaaldrich.com/technical-documents/protocol/protein-biology/immunohistochemistry/immunohistochemistry-protocol#antigen_retrieval.