Does anyone know if there are commercially available quality controls for test kits? I know the Hanna checkers have calibrators, but I don't think I've heard of any manufacturer having QC. I work in a hospital laboratory, and not being able to do QC to absolutely ensure that the test kits are working correctly drives me bananas! I can probably use RODI as a negative control for several of the analytes, but that's assuming the RODI water doesn't have any nitrates, nitrites, phos, ammonia, etc. Positive controls though? Not a clue!