sandwich ELISA

[Keld Sorensen]

Non-specific signal is often due to the concentration
of the antibodies involved. Try diluting and compensate
by using a higher sensitivity substrate.

Also: all polyclonal Abs have reactivity with E coli
proteins (from the animal) if they are not 
affinity purified - so either use affinity purified
polyclonals or adsorb out the E coli reactivity.

Typically, assays use Tween 20 (at 0.05%) rather
than ionic detergents.

Keld Sorensen.