Luminol in Chemiluminescence: Methods, Mechanisms, and Uses
Luminol is a white-to-pale-yellow crystalline solid that is soluble in most polar organic solvents but insoluble in water. It exhibits chemiluminescence with a blue glow when mixed with an appropriate oxidizing agent.
Mechanisms
To exhibit its luminescence, the luminol must be activated with an oxidant. Usually, a solution containing hydrogen peroxide (H2O2) and hydroxide ions in water is the activator. In the presence of a catalyst such as an iron or periodate compound, the hydrogen peroxide decomposes to form oxygen and water:
2 H2O2 → O2 + 2 H2O
H2O2 + KIO4 → KIO3 + O2 + H2O
Laboratory settings often use potassium ferricyanide or potassium periodate for the catalyst. In the forensic detection of blood, the catalyst is the iron present in hemoglobin.[1]
Uses
Luminol (5-aminophthalylhydrazide) is so far the most frequently used CL reagent. The CL emission of luminol is based on its oxidation by hydrogen peroxide, hexacyanoferrate(III), permanganate, N-bromosuccinimide (or N-chlorosuccinimide), periodate, dichromate, persulphate, dichlorocyanurate or trichlorocyanuric acid, chlorate and electrogenerated hypobromite in alkaline medium.
Methods
Luminol is synthesized in a two-step process, beginning with 3-nitrophthalic acid.First, hydrazine (N2H4) is heated with the 3-nitrophthalic acid in a high-boiling solvent such as triethylene glycol and glycerol. A condensation reaction occurs, with loss of water, forming 3-nitrophthalhydrazide. Reduction of the nitro group to an amino group with sodium dithionite (Na2S2O4), via a transient hydroxylamine intermediate, produces luminol.
References
[1] Ples, Marek. "Chemiluminescence activated by blood". www.weirdscience.eu (in Polish). Archived from the original on 3 January 2015. Retrieved 23 December 2014.
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US $999.00-666.00/kg2024-12-25
- CAS:
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- Min. Order:
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- Purity:
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- Supply Ability:
- 5000
US $100.00-75.00/kg2024-12-25
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- 521-31-3
- Min. Order:
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- Purity:
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- Supply Ability:
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