Abstract: In order to establish a simple and rapid method for the polarographic analysis of manganese, manganese-2-(5-bromo-2-pyridylazo)-5-diethylaminophenol (5-Br-PADAP)-octyl polyethylene glycol phenyl ether (OP) system was studied by linear sweep polarography. The results showed that in Na2B4O7-NaOH (pH 11.0) buffer solution, manganese-2-(5-bromo-2-pyridylazo)-5-diethylaminophenol(5-Br-PADAP)-octyl polyethylene glycol phenyl ether (OP) complex at －0.73 V (vs. SCE) could produce a sensitive adsorption wave. The second-order derivative peak current of the wave revealed a linear relationship with manganese over the concentration range of 0.10－0.32μg/mL (r = 0.9989, n = 10). The detection limit was 0.05μg/mL. Meanwhile, this adsorption wave was an irreversible electrode process, which could be verified by various electrochemical methods. The electron transfer number was 2 and the effects of ions on peak current were also validated. This proposed method was used for the determination of manganese content in rice with a recovery rate ranging from 94.1% to 101.0% and a relative standard deviation of 1.9%.

Key words: manganese, adsorption wave, 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol (5-Br-PADAP), octyl polyethylene glycol phenyl ether (OP)