Here we have a local company who does water sampling, I would call a local company that does that and see if they have the gear and knowledge to sample something like this? I do believe if the fertilizer gets to hot it will breakdown and maybe even change the chemical compounds inside of the formula. I would not hold my breath on the company returning to much useful info due to liability reasons. just my thoughts.
Sterilize system buy new
nutrients and start over...rock and roll.. like Judith priest song head are gonna roll..new plants, new tomatoes and people will stare in amazement.