Catalytic determination of manganese at ultra-trace levels by flow injection analysis

The catalytic effect of Mn(II) on the oxidation of succinimide dioxime in alkaline medium was used for its photometric determination by a flow injection analysis procedure. Variation of the reaction temperature between 25 and 45°C allows the determination range to be extended from 0.2 to 1300 ng ml^-1, with a sampling frequency of 45 h^-1 and a relative standard deviation of 1.3-1.0%. Injection of the sample in a flow of EDTA solution overcomes most of the interferences. The proposed method has been applied to the determination of manganese in some analytical-reagent grade reagents and in food products such as coffee and rice.