Flow injection chemiluminescent detection of trace Co(II) with dibromoalizarin violet-H2O2-CTMAB system

Chemiluminescence was observed when dibromoalizarin violet was oxidized with hydrogen peroxide in alkaline solution. Trace amounts of Co (II) catalysed this CL reaction strongly, especially in the presence of the cationic surfactant cetyltrimethylammonium bromide, and the CL intensity was proportional to the concentration of Co(II). A flow injection system with CL detection was established to investigate this CL system. The optimum conditions for this CL reaction were investigated in detail, and the optimized flow injection parameters were determined by the modified simplex method. A CL analytical method for determination of ultratrace amounts of Co (II) was developed with a detection limit of 4 pg/mL. It was used for analysis of natural water samples, and the results compare very well with those from GFAAS. A possible mechanism for this CL reaction is proposed on the basis of studying CL spectra, absorption spectra, fluorescent spectra and HMO treatment for the reagent molecule. The effects of various types of surfactants on CL reaction are also discussed.