ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Determination of Manganese in Some Medicinal Plants and their Water Extracts by a Kinetic Spectrophotometric Method

K. L. Mutaftchiev

Department of Chemistry and Biochemistry, Higher Medical Institute, Pleven 5800, Bulgaria

E-mail: vmilibrpl@mbox.digsys.bg

Received: 25 June 2001

Abstract: The catalytic effect of manganese(II) on the oxidation of the dye 3-methyl-6-(2-chloroethoxy)-2- [2-methoxy-4-(N,N-diethylamino)phenylazo]benzothiazolium methyl sulfate with potassium periodate in the presence of 1,10-phenanthroline in weakly acidic media is investigated. The reaction is followed spectrophotometrically by measuring the decrease in the absorbance of the dye at λ = 550 nm. Under the optimum conditions (c_i: 4 × 10⁻⁵ mol dm⁻³ (dye), 6 × 10⁻⁴ mol dm⁻³ (potassium periodate), 1 × 10⁻⁴ mol dm⁻³ (1,10-phenanthroline), 0.1 mol dm⁻³ (buffer – pH 3.0), 70ºC, 8 min) ρ(Mn(II)) in the range 0.1—5 ng cm⁻³ can be determined by the fixed-time method with the detection limit of 0.03 ng cm⁻³. The developed method is highly sensitive, selective, and simple. The method was applied successfully to analyze decoctions (fruits of one-styled hawthorn and dog-rose) and infusions (blossom of German chamomile and leaves of spearmint) for trace amounts of free manganese(II) without separation and total manganese. Total manganese was also determined in these plants.

Full paper in Portable Document Format: 563a194.pdf

Chemical Papers 56 (3) 194–198 (2002)