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Liquid Chromatographic and Spectrophotometric Determination of Phenazopyridine Hydrochloride, Ampicilline Trihydrate, and Nitrofurantoine in Pharmaceutical Preparations

Abstract The present work describes two new liquid chromatographic (LC) methods and three new spectrophotometric methods for the simultaneous determination of phenazopyridine hydrochloride (PHEN), ampicilline trihydrate (AMP), and nitrofurantoine (NIT) in their binary combinations. In the LC methods, a Nucleosil C8 column with a mobile phase composed of methanol–acetonitril–water (42:42:16, v/v/v) with ultraviolet (UV) detection at 260 nm was used for a PHEN–NIT combination and a Nucleosil C8 column with a mobile phase composed of methanol–water (80:20, v/v) with UV detection at 240 nm was used for the PHEN–AMP combination. For spectrophotometric methods, a ratio spectra derivative spectrophotometric and two chemometric methods in spectrophotometry were used. In ratio spectra derivative spectrophotometric methods, analytical signals were measured at the wavelengths corresponding to either maximums and minimums for these drugs in the second derivative spectra of the ratio spectra obtained by using every other zero‐order spectra as the divisor in their solution in methanol–0.1 M HCl (1:1) for PHEN–NIT and PHEN–AMP mixtures in the 200–300 nm range. Principal component regression (PCR) and partial least‐squares (PLS‐1) methods were used as chemometric techniques. In these techniques, the concentration data matrix was prepared by using the synthetic mixtures containing these drugs in methanol–0.1 M HCl (1:1). The absorbance data matrix corresponding to the concentration data matrix was obtained by the measurements of absorbances at more than 14 wavelengths in the range 200–300 nm, at appropriate Δλ in the zero‐order spectra in both techniques for these two binary combinations. The spectrophotometric procedures do not require any separation step. The accuracy, precision, and the linearity ranges of the methods have been determined, and they have been validated by analyzing synthetic mixtures containing the title drugs. These four methods were successfully applied to the pharmaceutical formulations, capsule, and tablet, and the results were compared with each other.