Journal of Fluorescence, Vol. 15, No. 2, March 2005 (©2005) DOI: 10.1007/s10895-005-2518-2 Fluorimetry Studies of Oscillating Chemilumnescence in the Luminol H 2 O 2 KSCN CuSO 4 TMAOH System Abdolraouf Samadi-Maybodi, 1,2 Niloofar Naseri, 1 and M. J. Chaichi 1 Received March 14, 2004; accepted December 2, 2004 Oscillating chemical reactions are complex systems, involving a large number of chemical species. In oscillating chemical reaction, some species, usually a reaction intermediate, exhibit fluctuation in its concentration. In this report, visible oscillating chemiluminescence produced by the addition of luminol (3-aminophthalhydrazide) to the oscillating system of H 2 O 2 KSCN CuSO 4 TMAOH was investigated using spectrofluorimetry method. The effects of ingredient concentration of the oscillating system and complexing agents like citric acid and cysteine on the behavior of the oscillating system were investigated. Moreover, the influence of nonaqueous solvents such as ethanol and ethylene glycol has been studied. KEY WORDS: Oscillating chemiluminescence; luminol; fluorimetry; complexing agent; non-aqueous solvents. INTRODUCTION Oscillating chemical reactions are always complex systems involving a large number of chemical species, which can be categorized as reactants, products and inter- mediates that show unusual mechanisms [1,2]. Basically, an oscillating chemical reaction is the one where some species (usually a reaction intermediate) exhibit fluctua- tions in their concentration; such fluctuations are period- icity or non-periodicity under specific reaction conditions. For such oscillating reaction, at least three requirements must be met [3]. (a) The system should be far from thermo- dynamic equilibrium, under such conditions, spontaneous oscillations can be generated [4]; (b) there should be at least one autocatalytic step or, alternatively, cross cataly- sis between the two steps of the reaction mechanism; and (c) the system should possess at least two steady states under the initial conditions. 1 Department of Chemistry, Faculty of Basic Science, Mazandaran University, Babolsar, Iran. 2 To whom correspondence should be addressed. E-mail: samadi@umz. ac.ir The fluctuations are reflected in color changes (if the oscillating species exhibit different colors), pH changes (variations in the H + or OH − concentration in the medium), redox potential changes, etc. Several meth- ods, such as pH metery, potentiometry [5–8] and chemi- luminescence [9–11], have been applied in the inves- tigation of oscillating reactions. One of the oscillating reactions reported recently has an initial composition of H 2 O 2 KSCN CuSO 4 TMAOH, determined using conductometry method [12]. The sharp pulses of blue light (λ max = 424 nm) produced by the addition of luminol to the oscillating system H 2 O 2 KSCN CuSO 4 TMAOH are unlike the oscillation characteristic to this system. In basic aqueous solution, chemiluminescence results from the oxidation of luminol by hydrogen peroxide catalyzed by a transition- metal ion such as copper or cerium. The light-generating reaction of luminol has been the subject of many researches. Typical oscillation attributes such as the oscillation period and amplitude were recently used to evaluate their use in chemical analysis [7,8]. In regular oscillations, the oscillating period and amplitude depend strongly on the concentrations of the reaction ingredient [11]. 117 1053-0509/05/0300-0117/0 C  2005 Springer Science+Business Media, Inc.