Flow Injection Analysis of Manganese(II) with Umbelliferone as a Novel Chemiluminescent Reagent

A novel chemiluminescent reagent, umbelliferone.. was proposed for the determination of manganese(II) using a FIA system. Umbelliferone, a derivative of coumarin, reacted with manganese (II) to strongly emit luminescence in the presence of hydrogen peroxide. Copper (II) and cobalt(II) emit luminescence weakly in an alkaline solution containing Umbelliferone and a surfactant. Among the examined surfactants, cetyltrimethylammonium bromide (CTAB) provided the highest enhancement of the CL intensity, approximately 36-times higher than that in the absence of a surfactant. Anionic and nonionic surfactants did not show any effect on the CL intensity enhancement. The flow system used had two channels. A carrier (distilled water, line 1) and a hydrogen peroxide solution (line 2) as a oxidizing agent were pumped at 0.72 cm(3)/min and 0.34 cm(3)/min, respectively. A sample solution (pH 9) of 50 mu L containing manganese (II), umbelliferone and CTAB was injected into the carrier line. The limit of detection of manganese(II) by the proposed method was 0.8 ppt. The determination range of manganese(II) was from 2.4 to 1000 ppt. The conditions for the determination of manganese(H) were as follows umbelliferone concentration, 5.0 X 10(-4) mol/L in sample solution; H(2)O(2), 1.9 mol/L in line 2 pH in sample solution, 9; CTAB, 5.0 X 10(-3) mol/L in sample solution; reaction temperature, 25 degrees C. The proposed method was applied to the determination of manganese(II) in river-water samples. The results of a trace manganese(II) determination in a standard sample showed good agreement with a certified value.