| Abstract: | A method was developed for the determination of vitamin B12 based on the enhancement of cobalt (II) on the chemiluminescence (CL) reaction between luminol and percarbonate (powerful source of hydrogen peroxide). The release of cobalt (II) from the vitamin B12 was reached by a simple and fast microwave digestion (20 s microwave digestion time and a mix of nitric acid and hydrogen peroxide). A charge coupled device (CCD) photodetector, directly connected to the cell, coupled with a simple continuous flow system was used to obtain the full spectral characteristics of cobalt (II) catalyzed luminol-percarbonate reaction. The optima experimental conditions were established: 8.0 m mol L?1 luminol in a 0.075 mol L?1 carbonate buffer (pH 10.0) and 0.15 mol L?1 sodium percarbonate, in addition to others experimental parameters as 0.33 mL s?1 flow rate and 2 s integration time, were the experimental conditions which proportionate the optimum CL emission intensity. The emission data were best fitted with a second-order calibration graph over the cobalt (II) concentration range from 4.00 to 300 µ g L?1 (r2 = 0.9990), with a detection limit of 0.42 µ g L?1. The proposed method was successfully applied to the determination of vitamin B12 in pharmaceuticals. |
