Hydrogen peroxide reaction with peroxyoxalates

The most commonplace substrates in energy-transfer analytical CL methods are aryl oxalates such as to(2,4,6-trichlorophenyl) oxalate (TCPO) and z s(2,4-dinitrophenyl) oxalate (DNPO), which are oxidized with hydrogen peroxide [7, 8], In this process, which is known as the peroxyoxalate-CL (PO-CL) reaction, the fluorophore analyte is a native or derivatized fluorescent organic substance such as a polynuclear aromatic hydrocarbon, dansylamino acid, carboxylic acid, phenothiazine, or catecholamines, for example. The mechanism of the reaction between aryl oxalates and hydrogen peroxide is believed to generate dioxetane-l,2-dione, which may itself decompose to yield an excited-state species. Its interaction with a suitable fluorophore results in energy transfer to the fluorophore, and the subsequent emission can be exploited to develop analytical CL-based determinations. 

An indirect method has been used to determine relative rate constants for the excitation step in peroxyoxalate CL from the imidazole (IM-H)-catalyzed reaction of bis(2,4,6-trichlorophenyl) oxalate (TCPO) with hydrogen peroxide in the presence of various ACTs . In this case, the HEI is formed in slow reaction steps and its interaction with the ACT is not observed kinetically. However, application of the steady-state approximation to the reduced kinetic scheme for this transformation (Scheme 6) leads to a linear relationship of l/direct measure of the rate constant of the excitation step. 

We have recently described a calibration procedure for the determination of excitation quantum yields on commercial fluorimeters, utilizing the luminol standard , and have thereby determined singlet excitation quantum yields for the peroxyoxalate reaction with bis(2,4,6-trichlorophenyl) oxalate (TCPO), hydrogen peroxide and imidazole, using various activators . The same calibration method has been utilized to determine the singlet quantum yields obtained in the induced decomposition of protected phenoxyl-substituted 1,2-dioxetanes 6 and and compared them to the well-investigated... 

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... 

Murata et al. [1099], separated three microcystins (RR, YR, and LR) as their dansylated derivatives. Peroxyoxalate chemiluminescence detection was chosen using a 0.5 mM bis[4-nitro-2-(3.6.9-trioxadesyloxycarbonyl)phenyl] oxalate with 50 mM hydrogen peroxide postcolumn reaction. This method gave a detection limit of 15fmol (S/N = 10), Linear working ranges were reported as 15-1670 fmol. Separation was achieved on a C j column (Jasco 885-CL chemiluminescence detector was optimal) with a 40/60 acetonitrile/water (0.05% TEA) mobile phase. Peak shapes and resolution were excellent and elution was complete in <10 min. 

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