Solvent extraction of manganese (VII) with a new analytical reagent

The optimum conditions for the spectrophotometric determination of manganese (VII) as an ion-association complex with triphenylmethane dye Crystal Violet (CV) by liquid-liquid extraction are presented. Crystal Violet was proposed as a new reagent for the spectrophotometric determination of micro amounts of manganese (VII). The ratio MnO4-:CV+ is 1 : 1. In acidic conditions, manganese (VII) forms a blue complex with CV, which can be extracted with 1,2-dichloroethane with an absorption maximum at 250 nm. Beer's law is obeyed in the range of 0.2-2.2 mu g ml(-1) manganese (VII). The molar absorptivity of the ion-pair is 1.54 center dot 10(4)l mol(-1) cm(-1), and Sandell's sensitivity is 3.57 center dot 10(-3) mu g cm(-2). The interferences of different cations and anions on manganese determination were also investigated. The proposed new method is extremely sensitive, rapid, reproducible and has been satisfactorily applied for the determination of trace amounts of manganese in plants.