Spectrophotometric Determination of Isoptin (Verapamil Hydrochloride) in Pharmaceutical Preparations using Bromothymol Blue Reagen

Verapamil Hydrochloride (VH) has been determined spectrophotometrically Using Bromothymol Blue (BTB). The method based on complexation between (BTB and VH). After shaking and diluting the complex solution with D.W, the pH was adjusted with NaOH and HCl to pH 4. The colored complex formed between VH and the reagent was transferred into separating funnels and extracted using 4.5 ml CCl4 and were shaken for (5 minutes). The extracted organic layer was used for preparation of the calibration curves for spectrophotometric measurements of VH at 420nm. The blanks were carried out in exactly the same way throughout the whole procedure. Molar absorptivity (ε L.mol-1.cm-1), detection limit, limit of linearity (μg.ml-1) and r2 were, 1.74*105, 0.009253, 0.08 and 0.9951 for (VH-BTB) respectively. The method was used with reasonable accuracy and precision for the determination of (VH) in synthetic samples of tablets, capsules and ampoules.