text: While the Kastle–Meyer test has been reported as being able to detect blood dilutions down to 1:10, there are a number of important limitations to the test. Chemical oxidants such as copper and nickel salts will cause the Kastle–Meyer reagent to turn pink before the addition of the hydrogen peroxide, thus it is vitally important to add the reagent first, then wait a few seconds, then add the hydrogen peroxide.
  The Kastle–Meyer test has the same reaction with human blood as it does with any other hemoglobin-based blood, so a confirmatory test such as the Ouchterlony test must be performed to definitively conclude from which species the blood originated.
  Color catalytic tests are very sensitive, but not specific. The positive color test alone should not be interpreted as positive proof of blood. A negative result is generally proof of the absence of detectable quantities of heme, however a false negative can be generated in the presence of a reducing agent. The test is unable to give specific evidence as to what is in the blood.