ENHANCEMENT OF PEROXYOXALATE CHEMILUMINESCENCE BY COPPER(II) IN FLOW-INJECTION ANALYSIS - OPTIMIZATION BY FACTORIAL DESIGN ANALYSIS

A flow injection analysis (FIA) system with peroxyoxalate chemilumines cence (CL) detection was optimized by factorial design analysis in the absence and presence of Cu(II) ions. The carrier stream was a mixture of acetonitrile and an aqueous imidazole solution of pH 7.0. The effe ct of the metal ions was determined by adding Cu(II) nitrate to the im idazole solution. A mixture of 5 mM bis(2-nitrophenyl)oxalate solution in acetonitrile and hydrogen peroxide was used as reagent solution. T he fluorophore used was 3-aminofluoranthene dissolved in acetonitrile to a concentration of 12.5 nM. The parameters of the factorial design experiment in the absence of Cu(II), were the concentration of hydroge n peroxide and imidazole, the percentage of acetonitrile and the lengt h of the mixing coil; those of experiments in the presence of the meta l ions, the concentration of imidazole and Cu(II) and the length of th e mixing coil. The enhancement of the chemiluminescence intensity by C u(II) in the FIA system was found to be 70%.