A simple and effective method for determination of the antithyroid drug carbimazole using ruthenium trichloride

Abstract

Abstract:An accurate, precise, and simple spectrophotometric method is proposed for the determination of the antithyroid drug carbimazole using ruthenium(III) chloride. This method is based on the formation at room temperature of a stable yellow-colored complex with λmax 370 nm. The method has a Beer's law range of 7.81 to 1.95 × 10 2 µ g mL −1 , molar absorptivity coefficient ε = 1.519 × 10 3 L mol −1 cm −1 , and correlation coefficient of 0.997. The metal:ligand (M:L) ratio of the complex was confirmed by the mole ratio and Job's method of continuous variation, suggesting a 1:2 stoichiometry. The formed carbimazole:Ru(III) complex was confirmed by spectral studies, including Fourier transform infrared, nuclear magnetic resonance, electron spin resonance, magnetic susceptibility, thermal analysis, and powder-X-ray diffraction. Our method could be adopted for routine analysis of carbimazole, due to its ease, affordability, and effectiveness.

Structural Refinement of Carbimazole by NMR Crystallography

“…Both PMLG-MAS and DUMBO-MAS spectra show greatly improved spectral resolution: five partially overlapped peaks are now clearly distinguishable, corresponding to the five groups of inequivalent protons, as expected on the basis of the molecular structure. As for the 13 C spectrum, also in this case, the spectral assignment was performed by comparison with the 1 H solution-state NMR spectra [ 43 , 46 ] and with the assistance of the 1 H- 13 C HETCOR experiment. All experimental isotropic 1 H and 13 C chemical shift values are reported in Table 2 along with the assignment of the peaks.…”