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 lambda(max) 370 nm. The method has a Beer's law range of 7.81 to 1.95 x 10(2) mu g mL(-1), molar absorptivity coefficient epsilon = 1.519 x 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.