FITC (fluorescein) and HRP (horse radish peroxidase) conjugated secondary antibody was used to detect nanogram – picogram levels of rabbit IgG by dot blot on nitrocellulose membrane. 4 ul each of serial 1 in 4 dilutions of rabbit IgG were dotted on nitrocellulose and allowed to dry. Membrane was blcoked in 3% BSA for 10 minutes dried for later use and rewetted with MB-070. Blot was incubated in fluorescein conjugated goat anti rabbit 611-1202 lot 25176 1:10,000 and HRP conjugated goat anti Rabbit (611-1302 lot 25406 1:10,000, dried and: A. Blot was imaged on the BioRad VersaDoc with filter settings appropriate for Fluorescein/DyLight 488 B. Blot was rewetted with TBS, incubated with FEMTOMAX chemiluminescent substrate for 1-3 minutes and imaged for 60sec on the BioRad VersaDoc Imaging System C. Blot was rinsed with TBS and DIH2O, incubated for 5 minutes with TMB Substrate for Western Blot MaxTag (1 ml of TMBM-102 + ~9 ml of TMBM-101), dried overnight and imaged using a conventional flatbed scanner