PHOTOMETRIC DETERMINATION OF FUROSEMIDE IN MEDICINAL FORMS AND BIOFLUIDS OF ATHLETES

Abstract

It was shown that furosemide (FUR) with the polymethine dye astrafloxin FF (AF) forms an ion associate (IA). Using the method of mathematical modeling, the energy efficiency of the formation of the IA is substantiated. Molecular modeling of FUR– + AF+ systems and related calculations were carried out using the HyperChem 8.0 package for various initial options for the arrangement of counterions relative to each other ("single point" procedure). Geometrical optimization of ions was carried out using the MM+ molecular mechanics method. The resulting AIs are fairly well extracted with various aromatic hydrocarbons. The maximum extraction of IA from the aqueous phase is achieved at pH 5-9. He effects of dye concentration on the optical density of toluene extracts of ionic associates of FUR with AF was studied. IA extraction reaches its maximum value at a dye concentration of (1.5–3.0)·10–4 M. The extraction equilibrium is reached in 50–60 s. The stoichiometry of IA FUR with AF was determined by spectrophotometric methods of isomolar series and equilibrium shift; the ratio of components is 1:1. A scheme for the formation and extraction of IA is proposed. The conditional molar absorption coefficient of IA is 1.0·105. The graduation graph of the dependence of the optical density of the extracts on the concentration of FUR is described by the equation of the straight line A = 0.012 + 0.051c in the concentration range of 0.8 – 45.6 μg/cm3 of FUR. The detection limit of FUR, calculated according to the 3s criterion (n = 5; P = 0.95), is 0.7 μg/cm3. A method of extractionphotometric determination of furosemide in dosage forms and biofluids of athletes was developed.