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Very fast peroxyoxalate chemiluminescence
Umeå University, Faculty of Science and Technology, Department of Chemistry.
Umeå University, Faculty of Science and Technology, Department of Chemistry.
1999 (English)In: Analytica Chimica Acta, ISSN 0003-2670, E-ISSN 1873-4324, Vol. 400, no 1-3, 257-264 p.Article in journal (Refereed) Published
Abstract [en]

Peroxyoxalate chemiluminescence (PO-CL) detection offers an advantage in chromatographic detection, by the virtue of its multiple unique selectivities and high sensitivity. However, many of the analytical separation techniques available today require observation times in the millisecond range to preserve the band resolution, and as the reaction kinetics of the PO-CL reaction is considerably slower, extra flow elements are needed to observe the reaction in a time window at maximum emission intensity. Since these flow elements increase the complexity of the system and contribute to band-broadening, the rational way to adapt PO-CL detection to miniaturised separation systems is to speed up the reaction, so that it emits an initial burst of light within the acceptable detection time-frame. Although this may result in a lower overall quantum yield, the actual detection sensitivity could be equal to, or better than slower PO-CL systems. By making careful selections of oxalic reagent and catalyst(s) the reaction can be fine-tuned to maximise the intensity. In this work, the time-dependent light emission from the reaction of bis(2,4,6-trichlorophenyl)oxalate (TCPO) was studied under the catalytic influence of imidazole, 1,2,4-triazole, 4-dimethylaminopyridine (DMAP), and 1,8-diazabicyclo-[5.4.0]-undec-7-ene (DBU) in acetonitrile. Both DMAP and DBU accelerated the reaction substantially, but the best combination of reaction speed and intensity was found for a mixture of 0.5 mM DBU and 5 mM 1,2,4-triazole, which reached its maximum emission after only 40 ms and had an emission intensity comparable to that seen with 5 mM imidazole as catalyst.

Place, publisher, year, edition, pages
Amsterdam: Elsevier, 1999. Vol. 400, no 1-3, 257-264 p.
Keyword [en]
chemiluminescence, peroxyoxalate, fast reaction, 1, 2, 4-triazole, 1, 8-diazabicyclo-[5.4.0]-undec-7-ene (DBU)
National Category
Analytical Chemistry
URN: urn:nbn:se:umu:diva-3057DOI: 10.1016/S0003-2670(99)00626-1ISI: 000084204200021OAI: diva2:141502
Available from: 2003-01-24 Created: 2003-01-24 Last updated: 2016-08-26Bibliographically approved
In thesis
1. Peroxyoxalate Chemiluminescence for Miniaturized Analytical Flow Systems
Open this publication in new window or tab >>Peroxyoxalate Chemiluminescence for Miniaturized Analytical Flow Systems
2003 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

This thesis deals with the peroxyoxalate chemiluminescence (POCL) reaction and its application as a detection technique in flow systems for chemical analysis. Particularly, miniaturized flow systems aimed for separation of molecules. In such systems, a high light intensity and a rapid development of the emission are the desired reaction characteristics, for reasons discussed in this text. The work tries to develop an understanding of the chemical processes involved in POCL, with special emphasis to the species favoring or hindering a rapid light evolution. Hence, is the focus placed on the nature of catalysis and the desired properties of substances acting as catalysts in this reaction. Consequently, the scientific papers on which this work is founded includes both systematic stopped-flow studies of catalyst candidates and of the causes for diminished light emission. In addition, multivariate strategies for reaction optimization in practical analysis situations are treated, and the application of the POCL technique to detection of serum-extracted neuroactive steroids, derivatized with fluorescent moieties, is presented.

From the experiments in this thesis it is clear nucleophilic catalysts are the most efficient enhancing compounds, which means that they must possess a carefully balanced characteristics of nucleophilicity, leaving group ability, and basicity. The investigations also conclude that the feature of basicity efficiently can be delegated to a non-nucleophilic co-catalyst, which allow the use of nucleophilic catalysts that need to be deprotonated to be active. This thesis also shows the importance of minimizing the amount of competing nucleophiles at the site of reaction to maintain the emission. This implies that also solvents and buffer substances should be carefully chosen not to interfere with the emission process.

The most promising combination of catalysts found in this work was 4,5- dichloroimidazole together with 1,2,2,6,6-pentamethylpiperidne. This arrangement was capable of speeding the reaction more than tenfold while increasing the maximum emission intensity by about the same factor.

37 p.
peroxyoxalate, chemiluminescence, nucleophilic catalysis, non-nucleophilic base, imidazole, triazole, aminopyridine, miniaturized, flow system, capillary electrophoresis, multivariate
Research subject
Analytical Chemistry
urn:nbn:se:umu:diva-16 (URN)91-7305-377-5 (ISBN)
Public defence
2003-01-24, 00:00
Available from: 2003-01-24 Created: 2003-01-24 Last updated: 2012-06-05Bibliographically approved

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