Frequently seen on TV shows like CSI, luminol is a chemical used by forensic investigators, which glows blue when exposed to trace amounts of blood at crime scenes. It's typically combined with hydrogen peroxide as a coreactant, although this can produce false positives. Scientists have recently had better luck by instead mixing it with artemisinin, which is commonly used as an antimalarial treatment.

When combining luminol with hydrogen peroxide, false positives can occur due to interference from metal ions and byproducts from the breakdown of the hydrogen peroxide. This means that substances other than blood will cause the luminol to glow.

Led by Guobao Xu from the Chinese Academy of Sciences, the research team instead tried combining luminol with artemisinin – while it's still a peroxide, it's structurally more sound than hydrogen peroxide, plus it's more resistant to interference.

In lab tests, the luminol/artemisinin mix was found to be superior at distinguishing blood from other substances that produce chemically-similar types of stains, such as coffee, tea and brown sugar.

A paper on the research was recently published in the journal Analytical Chemistry.

Source: American Chemical Society