I am using probes (50Kda cutoff) from Amuza Inc to sample oxytocin from the hypothalamus of rats. Before performing the experiment on rats, I did an invitro experiment to determine recovery rate for the probes using a known oxytocin standard.

However, I get no signal (ELISA) from the recovered perfusates. All the invitro recoveries were done on ice and samples collected into 0.1N HCL.

Am I missing something? Does it have to do with the stability of oxytocin? Also, does extraction of the sample with TFA help?

Any help is appreciated.