Abstract

Two simple, sensitive, and accurate spectrophotometric methods were developed for the determination of phenylephrine hydrochloride (PHE·HCl) in its pure form and pharmaceutical dosage forms. In method (A), PHE·HCl reacts with diazotized 3,4,5-trimethoxyaniline (TMA) via a diazo-coupling reaction to form a yellowish-orange azo dye soluble in an aqueous medium, exhibiting a maximum absorbance at 454 nm. Method (B) is based on cloud point extraction, in which Triton X-114 is added to the azo dye solution without altering its color or absorption maximum. The experimental conditions affecting both methods were systematically optimized. Under the optimized conditions, Beer’s law was obeyed over concentration ranges of 1–22 μg mL^-¹ and 0.3–12 μg mL^-¹ for methods (A) and (B), respectively. The determination coefficients (R²) were 0.9993 and 0.9976, while the molar absorptivities were 1.80 × 10⁴ m² mol^-¹ and 3.73 × 10⁴ m² mol^-¹ for methods (A) and (B), respectively. Sandell’s sensitivities were 1.13 × 10^-⁸ kg m^-² and 5.4 × 10^-⁹ kg m^-². The limits of detection and quantification were 0.08 μg mL^-¹ and 0.29 μg mL^-¹, respectively. Both methods were successfully applied to the determination of PHE·HCl in pharmaceutical preparations, including drops and tablets, with satisfactory recoveries ranging from 100.34% to 102.48%. In addition, the environmental impact of the proposed methods was evaluated using greenness assessment tools, confirming their ecofriendly analytical profiles.

Keywords: phenylephrine hydrochloride, cloud point extraction, 3,4,5-trimethoxyaniline, spectrophotometry, analytical greenness

Article language: En