The Influence of Imidazole and bis(Trichlorophenyl)oxalate in the Oxalyldiimidazole Peroxyoxalate Chemiluminescence Reaction

Malin (Stigbrand) Emteborg, Einar PontÚn and Knut Irgum*
Department of Analytical Chemistry, Umeň University, S-901 87 Umeň, Sweden.

The complex role of imidazole when used as a catalyst in the bis-(2,4,6-trichlorophenyl)-oxalate (TCPO) peroxyoxalate chemiluminescence (PO-CL) reaction is explained by the transient formation and subsequent degradation of 1,1’-oxalyldiimidazole (ODI). When ODI was used directly as PO-CL reagent, the stability was improved by addition of TCPO as an "imidazole sponge", since ODI is rapidly decomposed in the presence of imidazole. In this way the imidazole-catalyzed degradation of ODI was hindered efficiently. The stability of ODI was also influenced by the storage vessel material. Polymeric bottles were found to be more suitable than glass containers.

A comparison was made between the traditionally used reagent TCPO/imidazole (mixed on-line for formation of ODI) and the new reagent combination ODI-TCPO (pre-mixed) with respect to sensitivity, noise and background.

Anal. Chem., accpeted. Tentative publication date July 1, 1997.

Last updated March 20, 1997 by Knut Irgum, e-mail

Since 97-03-10