Why did it take more than 8 days for Cornell and The New York State Department of Agriculture & Markets (NYSDAM) to find the toxin? Scientific American suggests that Cornell — one of the first labs in testing pet foods against accidents and terrorism* — was ill-prepared in testing pet foods since it had limited access of comparison toxins and NYSDAM had problems loading the wet food into the machines for testing.
Cornell’s initial tests were inconclusive, so the university sent samples to the NYDASM food safety lab, which has an expanded set of contaminants to compare with the food. This lab detected aminopterin after switching to a UV-light detector to help them visualize the poison; it was initially difficult to pinpoint because of the food’s gummy consistency, which makes it hard to load into their machines and then to isolate out components. Goldstein says that Cornell is now trying to replicate NYDASM’s results in an attempt to prove definitively that aminopterin is the culprit.
Also, the article states that the lab received food samples and bodies before the recall. If Menu Foods was so worried about the food, why did it wait to announce it? The article tells us the process in finding toxins in wet pet food (Geek alert!):
[Cornell] received samples of both food products and animal remains from Menu Foods a day or two before the recall. Using liquid chromatography-mass spectrometry (a process that separates complex mixtures and analyzes ingredients by measuring a weight-to-charge ratio), researchers compared the constituent chemicals in the food to standards for common molds, heavy metals and ethylene glycol (or antifreeze, which Goldstein says is the number one cause of kidney failure). All test results were negative.
* = “The two labs are part of a network created after the Sept. 11 terrorist attacks to keep the nation’s animals and food supply safe.” - AP