Peroxy oxalate chemiluminescence

Figure 13, indicates that the first mole of phenol is released in <30 s, the same elapsed time for the chemiluminescence to reach a maximum intensity. In fact, the measured rate constant r, for the rise in the chemiluminescence emission, is identical to the rate of the first phenol s release from the oxalate ester. Furthermore, the slower rate of release of the second phenol ligand has a rate constant that is identical to the chemiluminescence decay rate f. Thus, the model allows a quantitative analysis of the reaction mechanism, heretofore not available to us. We intend to continue this avenue of investigation in order to optimize the chemiluminescence efficiencies under HPLC conditions and to delineate further the mechanism for peroxy-oxalate chemiluminescence. 

Since its discovery by Chandross and to this day, peroxy-oxalate chemiluminescence has been controversial because of its enormous complexity in view of the many alternative steps involved in this process. The principal mechanistic feature of the peroxy-oxalate chemiluminescence pertains to the base-catalyzed (commonly imidazole) reaction of an activated aryl oxalate with hydrogen peroxide in the presence of a chemiluminescent activator, usually a highly fluorescent aromatic hydrocarbon with a low oxidation potential . A variety of putative high-energy peroxide intermediates have been proposed for the generation of the excited states . In the context of the present chapter, it is of import to mention that recent work provides experimental evidence for the intervention of the 1,2-dioxetanedione 18 (Scheme 11) as the high-energy species responsible for the chemiexcitation. Furthermore, clear-cut experimental data favor the CIEEL mechanism as a rationalization of the peroxy-oxalate chemiluminescence . 

ICSC (International Chemical Safety Cards), 747, 749, 753-5 IgB (gamma-globulin), 655 Illumination, deterioration evaluation, 656 Imidazole chemiluminescence, 647 peroxy oxalates, 1189, 1190, 1256-7, 1259-61, 1263, 1265... 

M Wada, K Nakashima, N Kuroda, S Akiyama, K Imai. Sensitive flow-injection method with peroxy-oxalate chemiluminescence detection combined with preparative high performance hquid chromatography for determination of choline-containing phospholipids in human serum. J Chromatogr B 678 129-136, 1996. 

Sato K, Tanaka S. Determination of metal ions by flow injection analysis with peroxy-oxalate chemiluminescence detection. Microchem J 1996 53 93-8. 

V7. Van Zoonen, P., Bock, H., Gooijer, C., Velthorst, N. H., and Frei, R. W., Quenched peroxy-oxalate chemiluminescence detection in aqueous liquid chromatographic separations. Anal. Chim. Acta 200, 131-141 (1987). 

Fluorimetric reaction detectors were developed by Reh and Schwedt and by Verbeke and Vanhee [205, 206], and fluorimetric detection has been the rule in postcolumn derivatization reactions of steroids, including the use of such fluorophores as glycinamide [207], benz-amidine [208] and 3-chloroformyl-7-methoxycoumarin [209]. Dansylated steroids were separated by reversed phase HPLC and the pre-column derivatization was complemented by a post-column treatment with peroxy-oxalate and detection by chemiluminescence [210]. 

We thank Prof. Dr. J. Stauff, Frankfurt for his generous advice and his critical comments. The chapter dealing with Peroxy-oxalate chemiluminescence has been commented up on critically by Dr. M. M. Rauhut, Stamford, Connecticut which we gratefully acknowledge. 

Extensive mechanistic investigations of this reaction [5] and that of certain mixed oxalic anhydrides [6], with a variety of fluorescers resulted in new chemiluminescent systems, surpassing the best previously reported (e.g. luminol, p. 77, lucigenin, p. 109). As.intermediates, at leastdn ether solution, mono- and di-peroxy-oxylic acid, such as (1) and (2) were proposed. The role of the added fluorescers was thought to be that of inducers of radical reactions [6]. 

---