Investigation of Molybdate(II)-Rutin Complex and the Determination of the Dissociation Constant of Rutin in Water-Ethanol Mixture

Abstract

By the application of the spectrophotometric methods the composition of the complex and by the pH-metric method the reaction of complex formation, were determined. It was found that a complex MoO₃C₂₇H₂₆O₁₆H₂ ²⁻ was formed. The dissociation constant of rutin was determined pH-metrically at (20.0±0.1)[ddot]C (k_d=8.64 × 10⁻¹⁵). The concentration stability constant of the complex was determined by Bent-French and Bjerrum's methods, at various pH-values. Conditions are also given for the spectrophotometric determination of rutin by means of molybdate(II) as well as the accuracy of the method proposed. All Spectrophotometric measurements were done in 70% ethanol, at pH=6.30± 0.05 and ionic strength 0.015, whereas the determination of rutin was carried out in 50% ethanol, at pH=6.40±0.05, at room temperature (20[ddot]C) and the same ionic strength.