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Turkish Journal of Chemistry

DOI

-

Abstract

The catalytic effect of manganese (II) on the oxidation of the dye 1,3-Dimethyl- 2 [4-N (N,N-dimethylamino) phenylazo] imidazolium perchlorate (BR) with potassium periodate in the presence of 1,10-phenanthroline was investigated. The reaction was followed spectrophotometrically by measuring the decrease in the absorbance of the dye at 540 nm. Under optimum conditions (5 \times 10^{-5} mol dm^{-3} BR, 2 \times 10^{-4} mol dm^{-3} potassium periodate, 1 \times 10^{-4} mol dm^{-3} 1,10-phenanthroline, 0.1 mol dm^{-3} buffer -- pH 3.0, 70 °C, 5 min) manganese (II) in the range 0.1--4.5 ng cm^{-3} can be determined by the fixed-time method with a detection limit of 0.03 ng cm^{-3}. The developed method is highly sensitive, selective, and simple. The method was applied successfully to analyse infusions of some medicinal plants (common balm, creeping thyme, common lungwort, and colt's-foot) for trace amounts of total manganese and free manganese (II) ions without separation. The results showed good agreement with those obtained by atomic absorption spectrophotometry.

Keywords

manganese determination, catalytic spectrophotometric method, medicinal plants, infusions

First Page

619

Last Page

626

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