Which chemical is commonly used to detect latent blood at a crime scene?

Luminal is a chemical commonly used in forensic investigations to detect latent blood at crime scenes. When luminal is sprayed in areas where blood may be present, it reacts with the iron found in hemoglobin, the protein in red blood cells that carries oxygen. This reaction produces a blue luminescent glow, making the latent blood visible in dark conditions, such as during nighttime investigation or in poorly lit areas. This property is crucial for investigators as it allows them to locate blood evidence even when it has been cleaned up or is not immediately visible.

Other options, while they have specific applications in forensic science, do not serve the same purpose for detecting latent blood. For instance, oxidizers may have a role in chemical reactions, but they are not specifically utilized for blood detection. Phenolphthalein is a chemical reagent that can indicate the presence of blood, but it requires a visible sample for effective testing rather than revealing latent blood. Iodine can be used in various chemical tests, such as for starch, but it is not specifically known for detecting blood stains at a crime scene.