THE PHENYLDIAZONIUM 2-BENZOYL-1,1,3,3-TETRACYANOPROPENIDE AS AN ANALYTICAL REAGENT FOR PHOTOMETRIC DETERMINATION OF FLAVONOIDS
In this work for the first time the possibility of using phenyldiazonium 2-benzoyl-1,1,3,3-tetracyanopropenide (PDCP) for the quantitative determination of polyphenols (flavonoids) in medicinal products is shown using the “Ascorutin” tablets as an example. Photometric determination of rutin belonging to the group of plant polyphenols in “Ascorutin” tablets was carried out via the azocoupling reaction with the PDCP reagent in an alkaline medium. It was revealed that the reagent has long-term stability both in the solid state and in aqueous and aqueous-alcoholic solutions, in contrast to other diazonium salts used in photometry. The amount of rutin was determined according to a calibration graph constructed by measuring the optical density of solutions of rutin of various concentrations with the PDCP reagent (at a wavelength of λ = 430 nm). Experimentally, the molar absorptivity of light absorption was found, which is 3.3·10<sup>3</sup> [l/(mol·cm)]. To exclude the possible influence of the ascorbic acid contained in “Ascorutin” on the azocoupling reaction with PDCP, the absorption spectra of the reagent in the presence of ascorbic acid were studied. As shown by experimental data, the introduction of ascorbic acid into the aqueous-alcoholic solution of the reagent does not affect the form of its absorption spectrum. It was found that the detection limit of phenolic compounds in the preparation “Ascorutin” in terms of rutin is 3·10<sup>-6</sup> mol/l. The proposed method using the synthesized PDCP reagent is simple and convenient, has high sensitivity and selectivity, and can be recommended for the determination of phenolic compounds in pharmaceuticals.