Simultaneous Infrared Spectrometric Determination of Lisinopril and Hydrochlorothiazide in Tablets by Chemometric Methods

Sayyed Hamid Ahmadi, hassan tavakoli, Mohammad Reza Sangi, Majid Amirzadeh


A new Fourier transform infrared (FTIR) spectrometric method was developed for assaying hydrochlorothiazide (Hctz) and lisinopril (Lnp) in binary solid pharmaceutical formulations. Initially, the mixture of hydrochlorothiazide and lisinopril in solid mixtures was analyzed using FT-IR spectrometry in mid-IR range. Simultaneous determination of Hctz and Lnp carried out with inverse least squares (ILS) multivariate calibration of infrared spectra of binary standards of the drugs. The spectral range of1508-1850 cm-1was selected for the measurement in methanolic solutions. In this method the statistical parameters such as R2for Hctz and Lnp were 0.9995, 0.9994 and relative standard deviation (RSD) for Hctz and Lnp were 0.71%, 0.63% (n=6), respectively. Detection limits of Lnp and Hctz were obtained 0.75 and 0.90 mg/mL, respectively. USP methods were also used for comparing with proposed method, as a reference method. The proposed method was successfully applied to the determination of these drugs in laboratory-prepared mixtures and in commercial tablets. This method has suitable accuracy, precision, repeatability; and is comparable with reference standard methods


Lisinopril determination, FT-IR spectrometry, Hydrochlorothiazide determination, Pharmaceutical tablets.

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