Study on the mechanism and applications of the fluorescence reactions among cobalt (II), H2O2 and two new derivatives of 8-sulfonamidoquinoline

The fluorescence intensities of the reaction systems of Co(II) with two new 8-sulfonamidoquinoline derivatives, 5-(4-Chlorophenylazo)-8-(benzenesulfon amido)-quinoline (CPBSQ), which was firstly synthesized and characterized, and 5-(3-fluo-4-chlorophenylazo)-8-(benzenesulfonamido)quinoline (FCPBSQ), could be enhanced by H2O2. The mechanism and analytical characters of these reactions in the presence of H2O2 were investigated in this paper. CPBSQ a nd FCPBSQ reacted with Co(II) in the presence of H2O2 and in the basic medi um forming a chelate, which exhibited an intensive fluorescence in ultravio let region. The fluorescence intensities were proportional to the concentra tion of Co(II) over the range of 0.1-100 and 0.5-200 mu g/l with the detect ion limits of 0.05 and 0.10 mu g/l for the CPBSQ and FCPBSQ systems, respec tively. A lot of metal ions included Cu(II) and Ni(II) did not interfere th e determinations for both the systems. The methods, which are high sensitiv e and more selective, have been successfully applied to the determination o f trace amount of cobalt in environmental and biological samples. (C) 2000 Elsevier Science B.V. All rights reserved.