The fast peroxyoxalate-chemiluminescence of 3-1-aza-4,10-dithia-7-oxacyclododecane as a novel fluorophore Kiomars Zargoosh a,n , Mojtaba Shamsipur b,nn , Morteza Hosseini c , Claudia Caltagirone d , Vito Lippolis d a Department of Chemistry, Isfahan University of Technology, Isfahan 84156-83111, Iran b Department of Chemistry, Razi University, Kermanshah, Iran c Faculty of New Sciences and Technologies, University of Tehran, Tehran, Iran d Dipartimento di Chimica Inorganica ed Analitica, Universita ´ degli Studi di Cagliari, S.S. 554 Bivio per Sestu, 09042 Monserrato (CA), Italy article info Article history: Received 20 September 2011 Received in revised form 8 March 2012 Accepted 26 March 2012 Available online 3 April 2012 Keywords: Peroxyoxalate Chemiluminescence Fast reaction Imidazole TCPO abstract Due to their multiple selectivities, high sensitivity, and instrumental simplicity peroxyoxalate chemiluminescence (PO-CL) reactions have been used as powerful detection systems in several separation techniques. However many of the PO-CL reactions have slow kinetics and impose extra flow elements in separation systems to obtain acceptable band resolution, overcome the peak broadening and observe the reaction in a reasonable time window at maximum emission intensity. Therefore slow chemiluminescence reactions cannot be used in constructing miniaturized separation systems. To achieve the fast and intense PO-CL reactions (suitable for miniaturized separation systems) careful selection of the fluorophore molecule and the reaction conditions is of great importance. In this work, the time-dependent light emission of the fast chemiluminescence (CL) arising from the reaction of bis(2,4,6-trichlorophenyl)oxalate (TCPO) with H 2 O 2 in the presence of 3-1-aza-4,10-dithia-7- oxacyclododecane (L) as a novel fluorophore, and imidazole as catalyst, has been studied in ethyl acetate solution. To find the best time-intensity emission curves the concentration of TCPO, imidazole, hydrogen peroxide and L were optimized. The maximum CL intensity and minimum reaction time were obtained at the concentration of 0.2 M H 2 O 2 , 2.0  10 3 M TCPO, 1.0  10 3 M fluorophore and 5.0  10 3 imidazole. Under the optimum experimental condition, the entire CL reaction is completed in less than 3 s. & 2012 Elsevier B.V. All rights reserved. 1. Introduction Peroxyoxalate-chemiluminescence (PO-CL) is a powerful tech- nique for the sensitive determination of a large variety of analytes, depending on the roles they play in the CL reaction as fluorophore [1–4], catalyst [5], quencher [6–8] or oxidant [9,10]. Multiple unique selectivities, high sensitivity and instrumental simplicity of these chemiluminescence reactions make PO-CL a valuable detection system in analytical separation techniques such as liquid chromatography [11,12] and capillary electro- phoresis [13,14]. The coupling of CL detection with separation methods can significantly increase the sensitivity over absorbance and fluorescence measurements, because CL emission is measured against a dark background (detection limits of the CL methods show 10–100 times improvements compared to conventional fluorescence) [15]. In addition CL detection methods are naturally more selective than fluorescence detection systems, because CL intermediate(s) are unable to excite all fluorescent compounds. However, CL emission is not constant but varies with time (light flash composed of a signal increase after reagent mixing, passing through a maximum, then declining to the baseline), thus care must be taken to detect the signal in the flowing stream at strictly defined periods. Also, many of the PO-CL systems have slow reaction kinetics and require times in minute range. At the other hand, many of the analytical separation techni- ques available today require observation times in the millisecond to second range to preserve the band resolution. To save the peak resolution and observe the reaction in a time window at max- imum emission intensity, extra flow elements have been intro- duced in post column CL detection systems by several researchers [16]. Since these flow elements increase the size and complexity of the system, miniaturized separation systems cannot be con- structed using slow CL reactions as detection systems [17]. The rational way to adapt PO-CL detection to miniaturized separation systems is to speed up the reaction, by making careful selections of the fluorophore, oxalic ester and reaction conditions. In recent years, we have studied the chemiluminescence reactions of Contents lists available at SciVerse ScienceDirect journal homepage: www.elsevier.com/locate/jlumin Journal of Luminescence 0022-2313/$ - see front matter & 2012 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.jlumin.2012.03.051 n Corresponding author. Tel.: þ98 3113913287; fax: þ98 3113912352. nn Corresponding author. Tel.: þ98 831 4223 307; fax: þ98 831 4228 439. E-mail addresses: Kiomarszargoosh@yahoo.com (K. Zargoosh), mshamsipur@yahoo.com (M. Shamsipur). Journal of Luminescence 132 (2012) 2126–2129