Indirect chemiluminescence

Figure 3.40 — Sensor for the indirect chemiluminescence determination of species based on electrode generation of OH" ions. (Reproduced from [272] with permission of Elsevier Science Publishers).

Toyo oka T, Kashiwazaki T, Kato M. On-line screening methods for antioxidants scavenging superoxide anion radical and hydrogen peroxide by liquid chromatography with indirect chemiluminescence detection. Talanta. 2003 60 467-475. 

E. S. Yeung and W. G. Kuhr, Indirect Detection Methods for Capillary Separations, Anal. Chem. 1991, 63, 275A J. Ren and X. Huang, Indirect Chemiluminescence Detection for Capillary Electrophoresis of Cations Using Co(III) as a Probe Ion, Anal. Chem. 2001, 731, 2663 M. Macka, C. Johns,... 

The thermolysis of peroxyacetate [28] and substituted peroxybenzoates [29] gives both direct and indirect chemiluminescence. Thermolysis of peroxyacetate [28] in benzene solution at 100° gives very weak direct chemiluminescence. The emission is so weak that an emission spectrum could not be obtained. When biacetyl, which has a considerably higher quantum efficiency for phosphorescence than acetophenone (Backstrom and Sandros, 1958), is used... 

The direct and indirect chemiluminescence measured for the substituted peroxybenzoates is remarkably dependent upon the nature of the substituent. The parent peroxybenzate [29a], and the p-OMe [29b], p-N02 [29d], and w-N02 [29e] substituted peroxybenzoates show very little direct... 

For the dimethylamino-substituted peroxyester [29c] a third type of behavior is observed. The corrected chemiluminescence intensity obtained is independent of the structure of the activator. This is just what is expected for simple indirect chemiluminescence where the activator is excited by energy transfer from some first-formed singlet state. As indicated above, the initial excited state in this system is p-dimethylaminobenzoic acid. Evidently, the electron donating p-dimethylamino-substituent renders the peroxybenzoate [29c] sufficiently difficult to reduce that the value of k2 is so small that the bimolecular path is never able to compete successfully with unimolecular decomposition. 

An indirect chemiluminescence immunoassay is an assay, with another component than the primary chemiluminescent emitter coupled to the antigen or antibody. This can be a cofactor or a catalyst or even a molecule capable of converting a non-chemiluminescent precursor to a chemiluminescent or potentially chemiluminescent species. Most indirect assays are enzyme mediated. 

Chemiluminescence reaction of a typical peroxyoxalate reagent (bis (2,4,6-trichlorophenyl) oxalate TCPO) with hydrogen peroxide to form reactive intermediates, (b) Energy transfer from the reactive intermediates to another molecule that emits light. The overall process is an example of an indirect chemiluminescence reaction... 

Indirect chemiluminescence has been used extensively for analysis and in the so-called chemical light sources the most well known of these reactions involve oxidation of certain diaryl oxalates and ox-amides. Instead of C returning to the ground state by photon ejection (as in the above reaction scheme), it can undergo energy transfer with a suitable fluor-ophore, which in turn may then exhibit its characteristic fluorescence emission ... 

The analytical utility of indirect chemiluminescence depends upon little or no emission resulting from C in the region of maximum emission from the electronically excited fluorophore together with efficient transfer of excitation energy. 

Molecular emission cavity analysis (MECA) is a flame chemiluminescence technique based on the generation of excited molecules, radicals, or atoms within a hydrogen diffusion flame. The excited species are formed by direct or indirect chemiluminescence mechanisms and are confined within the inner space of a small cavity, which is positioned at a preselected point of the flame environment. The emission is monitored at the characteristic wavelength of... 

Transient Four membered Rings.—Evidence has been presented for the intermediacy of Dewar-benzenes in the thermal rearrangement of bis-cyclopropenyl to benzene. When (572) was heated in acetonitrile, in the presence of 9,10-dibromoanthracene, fluorescence of the dibromoanthracene was observed. The nature of the excited state produced was identified as triplet xylene, which was shown to be produced from (572) via an intermediate. The activation energy for thermolysis of the intermediate, ca. 26kcalmol"S was less than that for the disappearance of (572). Of the three possible benzene isomers, only Dewar-benzene produces a significant amount of the indirect chemiluminescence, and the activation energies for the decomposition of the Dewar-benzenes (573) and (574) are close to that found for the intermediate in the thermolysis of (573). Comparison of the chemiluminescence yields from (572), (573), and (574) allowed the conclusion that the rearrangement of (572) could proceed almost totally via a dimethyl-Dewar-benzene. 

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