Luminol

A method frequently used in forensic chemistry is that employing luminol (as preemptory test), a derivative of phthalic acid, which reacts with metal cations and hence to detect traces of blood. The process involves mixing luminol with a polar solution dependent upon the method used to create the luminol base, which is spread carefully in places where it is thought that there are remnants of blood after all other evidence has be collected due to its destructive properties. Thus, typically the iron-shaped cation found in the heme group of hemoglobin reacts with luminol observing a blue luminescence of the reaction itself is carried out. However, due to the nature of luminol there are other metal ions that it can react with to produce false positives, for this reason alone that is why it is used only to determine the possibility of blood being present. In this process, the final product is the 3-aminophthalate anion which is in an excited state. Upon returning to the ground state (or basal) releases energy in the form of light, which is known as blue luminescence. The reaction described has a very slow cinétic. In fact it is the iron in the heme group of hemoglobin, which catalyzes the process. Another note to keep in mind when working with luminol is that the reagent is only viable for a maximum of ten minutes and the darker the room the better the test.