It is possible.  You can do a second peroxidase block AFTER development of
first chromogen to quench any residual peroxidase from HRP step.  Develop
first chromogen color, go back to PBS rinse, then do a second endog
peroxidase block, and proceed with second HRP protocol.  


Gayle Callis
MT,HT,HTL(ASCP)
Histopathology Supervisor
Veterinary Molecular Biology - Marsh Lab
Montana State University - Bozeman
19th and Lincoln St
Bozeman MT 59717-3610

406 994-6367
406 994-4303 (FAX)