Rapid determination of telmisartan in pharmaceuticals and serum by the parallel catalytic hydrogen wave method

Abstract

The polarographic characteristics of telmisartan have been investigated in 0.8 mol L⁻¹ NH₃.H₂O–NH₄Cl (pH 8.9)–0.01 mol L⁻¹ H₂O₂ as supporting electrolyte. The results demonstrate that the polarographic reduction wave at ca. −1.30 V in the absence of H₂O₂ is a catalytic hydrogen wave, and the reduction wave enhanced by H₂O₂ is a so-called parallel catalytic hydrogen wave. The analytical sensitivity of the parallel catalytic hydrogen wave is ca. 60 times higher than that of the corresponding catalytic hydrogen wave. Based on the parallel catalytic hydrogen wave a novel method has been developed for determination of telmisartan by linear sweep polarography. The calibration curve is linear in the range 2.0×10⁻⁸–2.0×10⁻⁶ mol L⁻¹ and the detection limit is 1.0×10⁻⁸ mol L⁻¹. The precision is excellent with relative standard deviations of 2.6% at a concentration of 1.0×10⁻⁷ mol L⁻¹ telmisartan. The proposed method has been applied to the direct determination of the telmisartan in capsule forms and biological samples. The proposed method has been proved to be advantageous over existing CZE and MEKC methods in simplicity, rapidity, and reproducibility.