Urine under black light: Cat urine, dog urine, human urine and other body fluids with high protein content glow under black light. Therefore, black light is excellent for finding such stains on carpet and upholstery.

Many body fluids contain fluorescent molecules. These molecules glow in a visible colour, for example blue, green or orange under the short-wave, high-energy light of an ultraviolet lamp. UV lamps are not only useful for cleaning, as they also reveal lemonade and juice stains, but are also used by forensics in a crime scene to make blood, urine or semen visible.

What causes urine to glow under black light

Due to the presence of certain compounds and substances that are fluorescent or phosphorescent, urine can glow under black light. Black light emits ultraviolet (UV) light, especially in the UVA spectrum, which is not visible to the human eye. Certain substances in urine can absorb this UV light and re-emit it as visible light, making the urine appear fluorescent or luminescent.

One of the main substances in urine that can cause this fluorescence is riboflavin, also known as vitamin B2. Riboflavin occurs naturally in many foods and is excreted in the urine. When exposed to UV light, riboflavin absorbs the energy and emits a visible greenish-yellow fluorescence.

It is important to note that the fluorescence of urine under black light may vary depending on factors such as individual diet, fluid balance and the presence of other compounds or medications. In addition, the intensity of fluorescence may vary from person to person and not all urine will glow brightly.