Tetramethylbenzidine as precipitating HRP substrate

David Micklem microlaserpro at lycos.com
Wed Dec 18 19:54:14 EST 2002

Hi all,

Tetramethylbenzidine (TMB) is often used as a substrate for
horseradish peroxidase in ELISA assays, where the water soluble colour
is an advantage.

I notice that several companies now sell stabilised TMB substrate kits
that include an additive that causes the end-product to precipitate,
so that TMB can be used for staining nitrocellulose membranes etc.

Does anyone have a recipe for a precipitating version of the TMB
substrate mix?  I don't mind making it up fresh each time, so I don't
need the extra-stabilised ready-to-use, just pour it in, keeps for
months commercial version...

Thanks for your help,


David Micklem
Dept. Genetics, Cambridge

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