"Chemiluminescence" (chemical luminescence) is the phenomenon arising from chemical reactions. Compounds generated in an excited state by chemical reactions, when released to the ground state, discharge light. Exposed to the atmosphere almost all materials generate chemiluminescence as a result of oxidation reactions. The Chemiluminescence Analyzer (CLA series) is the world’s most sensitive photon counting device. It detect down to 50 photons/cm2/sec (about 1/10000 of a firefly) 10-15 Watts
Many things emit ultra-weak light invisible to the human eye in the form of Chemiluminescence, Bioluminescence or Biophoton and research studies are carried out in several field to detect such invisible light. Especially Chemiluminescence is able to estimate the oxidation or deterioration levels of organic samples. Our instrument can be applied not only this oxidation field but also in a variety of other fields.
Formed during oxidation
The products of luminescence according to the Russell Mechanism are singlet oxygen and excited carbonyl arising from the bimolecular degradation of hydroperoxides*. When an excited carbonyl species is released to the ground state, it releases its energy as a photon of light. Therefore, by following this chemiluminescence, it is possible to measure the degree of oxidation or degradation of a sample. This is a unique and extremely sensitive measure of oxidation.
Auto oxidation mechanism
Samples are oxidized by heat, light or other stimulators. Then, according to the oxidation reaction, R・ or ROO・ will be produced and changing to peroxides (ROOH). When the peroxides are decomposed, peroxyradicals (ROO・) will be produced again and 2 molecules of peroxyradicals will produce the excited carbonyls and active oxygen such as singlet oxygen. When the excited compounds are released to the ground state, energy is released as heat or light. So, by measuring chemiluminescence, we can estimate the amount of peroxides or the level of a sample’s oxidation.
Typical Chemiluminescence(CL)Time-course Change
The following graph shows typical CL behaviour during heating measurement. As the sample is heated, the peroxide decomposes, and CL from the excited carbonyl increases, resulting in a peak (the first peak). This corresponds to the amount of peroxide at that point.
The oxidation reaction is then accelerated by heating in air or oxygen, and eventually the CL reaches a steady state. The intensity at this time is termed the steady-state luminescence intensity (Is). In the sample to which stabiliser has been added, the stabiliser is consumed, the steady state of the oxidation reaction is disrupted, and the amount of radicals in the sample increases, resulting in the appearance of significantly higher luminescence (the second peak). This point is called the oxidation induction time (OIT). The OIT can be used to evaluate the oxidative stability of the sample. Also, since Is is the steady state of radical extinction and formation within the sample, it represents the rate of radical generation, and this value can also be used to evaluate the oxidative stability of the sample.
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