Question

Write the principle involved in chemiluminescence and spectrometry for air pollutant determination. Also state the pollutants which can be analysed using these methods

Answer 1

Chemiluminescence (also chemoluminescence) is the emission of light (luminescence), as the result of a chemical reaction. There may also be limited emission of heat. Given reactants A and B, with an excited intermediate Int,

[A] + [B] → [Int] → [Products] + light

For example, if [A] is luminol and [B] is hydrogen peroxide in the presence of a suitable catalyst we have:

Luminol (C₈H₇N₃O₂) + Hydrogen peroxide (H₂O₂) -> 3-APA[Int] -> 3-APA + light

where:

3-APA is 3-aminophthalate

3-APA[Int] is the vibronic excited state fluorescing as it decays to a lower energy level.