DEVELOPMENT OF THE SPECTROPHOTOMETRIC METHOD FOR THE DETERMINATION OF METOPROLOL IN MEDICINES

Abstract

Introduction. The method of determination of metoprolol in a substance presented in the European Pharmacopoeia makes it impossible to quantify metoprolol tartrate in tablets. Scientists have developed a number of methods for the quantitative determination of metoprolol tartrate in mono- and combined drugs. However, they require expensive equipment or the use of toxic solvents.

The aim of the study – to develop a simple, express, low-cost method for the quantitative determination of metoprolol tartrate in tablets in compliance with the principles of “green” chemistry by UV-spectrophotometry.

Research Methods. To perform the study, we used the pharmacopoeial standard sample of metoprolol tartrate (Sigma-Aldrich, ≥98%, HPLC), methanol R ((“Honeywell Riedel-de Haen™”, 99.9 %), Metoprolol tablets, 50 mg (three different Ukrainian manufacturers of medicines). The optical density in the UV region was measured in quartz cuvettes (1 cm) on a two-beam scanning spectrophotometer Shimadzu UV-1800 (Japan) using the UV-Probe 2.62 software.

Results and Discussion. The UV spectrum of methanolic extraction of metoprolol from tablets has an intense absorption band at a wavelength of 224 nm, pharmacopoeial standard sample of metoprolol tartrate in methanol – 224 nm, which made it possible to quantify the specified wavelength. Uncertainty of sample preparation (∆_SP) for determination of metoprolol in tablets was 1.66 %, complete uncertainty of analytical method (∆_As) for determination of metoprolol in tablets was 1.80 %. The regression equation was y = 0.0314x – 0.2942, the correlation coefficient – 0.9964. The linearity parameters met the requirements of SPhU over the entire range of analytical methods (20–36 µg/mL). The limit of detection (LOD) of metoprolol was 3.27 µg/mL, the limit of quantification (LOQ) was 9.92 µg/mL. The precision of the experimental results was characterized by a low standard deviation in the studied range of concentrations of metoprolol, and the systematic error was 0.04 %.When studying the robustness of the analytical method, it was found that the solutions were stable for 2 hours. Assessment of the “greenness” of the analytical method using the analytical eco-scale and the method AGREE (Analytical GREEnness) proves that the developed method is exellent in accordance with the principles of “green” chemistry.

Conclusions. A simple, express method for the quantitative determination of metoprolol tartrate in tablets based on the principles of “green” chemistry by the method of UV-spectrophotometry has been developed. The proposed spectrophotometric method for the determination of metoprolol in medicines can be used in the routine work of laboratories for quality control of medicines with a limited budget, as it does not require expensive equipment.