Sunday, April 21, 2013
Luminol experiments with vegetables
Luminol is a chemical with the nice formula C8H7N3O2 and the official name 5-Amino-2,3-dihydro-1,4-phthalazinedione. It is used in forensic analyses to find blood traces on crime scenes and in biology to find iron, copper or cyanide in cells. Luminol is reacting with oxidizing chemicals like hydrogen peroxide (H2O2) and produces a blue glowing chemoluminescence. Under normal conditions this luminescence in invisible but the use of catalyst chemicals like iron or copper cause an intensive cold blue light. In blood the iron of the hemoglobin is reacting with luminol. Some plants contain a high amount of enzymes called peroxidases (horseradish peroxidase, HRP) that catalyst the reduction of peroxides and also the oxidation of luminol. The photos below show some vegetables that were treated with luminol. They react very different depending on the concentration of peroxidases.
I used the standard solution of luminol powder mixed with potassium hydroxide solution with a concentration of 10 % and hydrogen peroxide. The solution was brought on the fresh cut vegetable. The reaction started immediately and produced some mystic blue glowing. All photos are made with a exposure time of 25 seconds in almost total darkness, an aperture of 4.5 and film speed 400. With enough luminol it is possible to transform a market stall for vegetable into fairy lights.
A slice of radish:
And another piece of radish:
A small radish:
In tomato’s it reacts only the outer portion and the peel:
Cucumber with a weak chemoluminescence:
A piece of cabbage:
Lemon with a weak luminescence:
It is not only working with vegetables, eggs contain iron that reacts with luminol. But it causes a weak luminescence.