Oxalic acid derivatives, chemiluminescence

The brilliant emissions resulting from the oxidation of certain oxalic acid derivatives, especially in the presence of a variety of fluorophores, are the bases of the most active area of current interest in CL. This group of chemiluminescent reactions has been classified as peroxyoxalate chemistry because it derives from the excited states formed by the decomposition of cyclic peroxides of oxalic acid derivatives called dioxetanes, dioxetanones, and dioxetanediones. 

SCHEME 4. Chemiluminescence mechanism of an oxalic acid derivative in the presence of H2O2... 

A number of chemiluminescent reactions are known. The oxidation of 3-aminophthalhydrazide (luminol) has been studied extensively. " The emission resulting from the reaction of certain oxalic acid derivatives is another outstanding example. When chemiluminescence occurs in living organisms, it is called bioluminescence. The best known example is observed in the firefly Photinus pyralis. Many review articles have... 

Applications of the oxalate-hydrogen peroxide chemiluminescence-based and fluorescence-based assays with NDA/CN derivatives to the analysis of amino acids and peptides are included. The sensitivity of the chemiluminescence and fluorescence methods is compared for several analytes. In general, peroxyoxalate chemiluminescence-based methods are 10 to 100 times more sensitive than their fluorescence-based counterparts. The chief limitation of chemiluminescence is that chemical excitation of the fluorophore apparently depends on its structure and oxidation potential. 

The chemiluminescence reaction of esters of oxalic acid can proceed within a wider pH range than for luminol. However, the most efficient oxalate derivatives are only soluble in organic solvents such as ethyl acetate, acetonitrile, dioxane or dimethoxyethane and dissolution problems of these solvents in aqueous media are encountered. This can limit the use of this chemiluminescence reaction for a direct coupling to an H202-generating enzymatic reaction. 

The reaction of certain derivatives of oxalic acid with hydrogen peroxide in the presence of a suitable fluorescer represents an early demonstration of a relatively efficient, non-enzymatic chemiluminescent system (Rauhut, 1969). Work in this area was initiated by the report of Chandross on the chemiluminescent reaction of oxalyl chloride and hydrogen peroxide in the presence of anthracene (Chandross, 1963). While in subsequent work Rauhut... 

Chemiluminescence has been used as the detection system for derivatives produced by reaction of the analyte with hydrogen peroxide in the presence of an activated derivative of oxalic acid. Two applications are given as illustration ... 

The observation that oxalic peracids were especially efficient sources of electronic excitation energy in chemiluminescence, led to the search for other derivatives of oxalic acid capable of the formation of such peracids [2]. 

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