Spectrophotometric investigation of the formed chelate between timonacic and palladium(II) and its analytical applications.

A simple spectrophotometric method for the determination of timonacic is presented. The procedure is based on the chelate formation with palladium(II) chloride in buffered medium. The optimum conditions for the complex formation were ascertained and the method was developed for the determination of timonacic in the concentration range of 28-48 micrograms ml-1. The emperical formula of the formed complex was determined, by applying different spectrophotometric methods, at optimum pH of 4.8 and an ionic strength of mu = 0.5. The stoichiometric ratio was found to be 2:1 (timonacic/palladium) as calculated by the mole ratio, continuous variations and Asmus methods. The continuous variations and Nash methods were applied for the determination of the conditional stability constant of the formed yellow-water soluble complex and was found to be 3.27 x 10(7). The proposed methods was found to be suitable for the determination of timonacic in bulk and in its pharmaceutical tablets.