Pre-evaluation of metal ions as a catalyst on chemiluminometric sequential injection analysis with luminol–H2O2 system

Catalytic effect of metal ions on luminol chemiluminescence (CL) was investigated by sequential injection analysis (SIA). The SIA system was set up with two solenoid micropumps, an eight-port selection valve, and a photosensor module with a fountain-type chemiluminescence cell. The SIA system was controlled and the CL signals were collected by a LabVIEW program. Aqueous solutions of luminol, H2O2, and a sample solution containing metal ion were sequentially aspirated to the holding coil, and the zones were immediately propelled to the detection cell. After optimizing the parameters using 1 × 10−5 M Fe3+ solution, catalytic effect of some metal species was compared. Among 16 metal species examined, relatively strong CL responses were obtained with Fe3+, Fe2+, VO2+, VO3−, MnO4−, Co2+, and Cu2+. The limits of detection by the present SIA system were comparable to FIA systems. Permanganate ion showed the highest CL sensitivity among the metal species examined; the calibration graph for MnO4− was linear at the concentration level of 10−8 M and the limit of detection for MnO4− was 4.0 × 10−10 M (S/N = 3).