Comparison of Luminol and Luminol Sodium Salts

As we all know, in many movies and TV plays, criminal investigators can detect very small traces of blood at the scene of a crime that can not be observed by the naked eye. Even after scrubbing, blood stains can be detected even after many years. The main substance used here is Luminol, commonly known as Luminescent Ammonia.

Some enzymes in the biological system, such as horseradish oxidase HRP and iron in hemoglobin, can catalyze the decomposition of hydrogen peroxide and produce monooxygenated luminol, which emits blue fluorescence. The blue light can be exposed and developed by X-ray film, scanned by fluorescent CCD, and even observed by naked eyes in low light.

Of course, in our in vitro diagnosis of ivd, luminol is not just used to detect blood stains. Many substances that catalyze hydrogen peroxide can be detected. Usually we don't just use Luminol, but also the sodium salt of Luminol. Why is that?

The chemical name of Luminol is 3-aminophthalic hydrazide, which is a light yellow powder at room temperature and almost insoluble in water. But in biochemical tests, water is the preferred and most commonly used solvent. Colleague Luminol is an acylhydrazide, a strong acid and soluble in alkaline solution, so the use of Luminol is often in weak alkaline solution. Environment.

On the other hand, the sodium salt of Luminol can be dissolved in water and can be used in aqueous solution with pH close to 7. Because our blood pH is close to 7, sodium luminol is more suitable than luminol at this point.