Developing and validating a rapid, quantitative, and spectrophotometric analytical method for determining promethazine hydrochloride in its pure and pharmaceutical forms

A rapid, easy, and sensitive spectrophotometric approach for determining trace quantities of promethazine hydrochloride (PZH) in aquatic solutions was illustrated. The present study intends to develop a simple method centered on the (OCR) Oxidative Coupling Reaction to estimate PZH in pharmaceutical preparations. The drug PZH was oxidized by the oxidizing agent N-bromosuccinimide in the presence of anillinium chloride as a coupling reagent to create a green product with maximal absorbance at 589 nm. Under the optimized reaction conditions, this colored product was stable for more than 140 min at an initial pH of approximately 5.61. The sophisticated technique was also taken for granted for its linearity, as Beer's Lambert law was adopted over a wide concentration of 6.0 to 20 μg/mL with a greater correlation coefficient of 0.9996. The molar absorbency and value of the sandal index were 1.323 × 10 4 L.mol −1 . cm −1 , 3.1 × 10 −2 μg/cm 2 showing the maximal sensitivity of the developed mode. Additionally, the precision and accuracy of the latter were validated based on the calculated low relative standard deviation (RSD%) percentage of 0.467 %. Nonetheless, the limitations of detecting and quantifying PZH were in squence of 5.05 × 10 −7 μg/mL and 1.68 × 10 −6 μg/ml. Furthermore, PZH was successfully quantified in the promethazine ampule. HCl 50 mg.