What does Luminol specifically react with in a blood sample?

Luminol is a chemical that is commonly used in crime scene investigations to detect blood, even if it has been washed away or is not visible to the naked eye. It specifically reacts with the iron component found in hemoglobin, which is the protein in red blood cells that carries oxygen. When Luminol comes into contact with iron, it undergoes a chemical reaction that produces a blue glow in the presence of blood. This property makes it a valuable tool for forensic investigators, as they can identify potential bloodstains in various environments and under differing conditions.

The other choices, while relevant in the context of blood composition, do not accurately represent what Luminol targets. Myoglobin is found in muscle tissue and is not the primary focus for Luminol in blood samples. Proteins in blood can be many different types, but Luminol does not selectively react with them. Cholesterol, while present in blood, is not involved in the reaction that Luminol facilitates. Thus, the correct answer highlights Luminol’s specific reactivity with iron in hemoglobin, underscoring its role in forensic science for blood detection.