Has anyone found a good, universal, manufactured, replacement for serum in ELISA assays? i.e....to use as a diluent additive to maintain matrix when diluting standards for your curve.

I use the Liforcell serum replacement, available fom ISC BioExpress - its fairly cheap, and works well for both mouse and human samples. However, for most ELISAs, you can just use PBS+1% (*good quality* 99.5+% pure) BSA as an universal diluent. (except for applying the coating Ab in a sandwich-ELISA)