Quick disapperance of ECL signal - (Mar/28/2011 )

Our lab frequently encounter a problem. After adding mixed ECL onto PVDF membrane covered in a plastic bag, sometimes the signal is extraordinarily bright but diminishes very quickly within a few seconds, increasing the difficuly for long-term exposure. However, it seems that newly purchased ECL has no similar problems. Is it possible that contamination among two bottles of ECL kit causes this problem? Any suggestion?

Many thanks.

It could be that your protein is strongly expressed and the bound antibody is using up the substrate quickly. Contamination of the solutions is more likely to cause them to not work at all.