A direct, extraction-free spectrophotometric method has been developed for the determination of acebutolol hydrochloride (ABH) in pharmaceutical preparations. The method is based on ionpair complex formation between the drug and two acidic dyes (sulphonaphthalein) namely bromocresol green (BCG) and bromothymol blue (BTB). Conformity to Beer's law enabled the assay of the drug in the range of 0.5-13.8 µg mL-1 with BCG and 1.8-15.9 µg mL-1 with BTB. Compared with a reference method, the results obtained were of equal accuracy and precision. In addition, these methods were also found to be specific for the analysis of acebutolol hydrochloride in the presence of excipients, which are co-formulated in the drug.

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Two simple, rapid and sensitive extraction spectrophotometric methods have been developed for the assay of trazodone hydrochloride (TRH) in pure and pharmaceutical formulations. These methods are based on the formation of chloroform soluble ion-association complexes of TRH with bromocresol green (BCG) and with methyl orange (MO) in a KCl-HCl buffer of pH 1.5 (for BCG) and in a NaOAc-HCl buffer of pH 3.29 (for MO) with absorption maximum at 415 nm and at 422 nm for BCG and MO, respectively. The reaction conditions were optimized to obtain the maximum color intensity. The absorbance was found to increase linearly with increasing concentration of TRH, which was corroborated by the calculated correlation coefficient values (0.9992 and 0.9994). The systems obeyed the Beer law in the range of 0.9-17 and 1-20 ?g/ml for BCG and MO, respectively. Various analytical parameters were evaluated and the results were validated by statistical data. No interference was observed from common excipients present in pharmaceutical formulations. The proposed methods are simple, accurate and suitable for quality control applications.

Two simple, rapid and sensitive extractive spectrophotometric methods have been developed for the assay of cinnarizine (CNR) in pure and pharmaceutical formulations. The methods are based on the formation of chloroform soluble ion-association complexes of CNR with thymol blue (TB) and with cresol red (CR) in NaOAc-AcOH buffer of pH 3.6 for TB and in KCl-HCl buffer of pH 1.6 for CR with absorption maxima at 405 nm and at 403 nm for TB and CR, respectively. Reaction conditions were optimized to obtain the maximum color intensity. The systems obeyed Beer's law in the range of 0.6-15.8 and 0.8-16.6 mg mL -1 for TB and CR, respectively. Various analytical parameters have been evaluated and the results have been validated by statistical data.

Two simple, rapid and sensitive extractive spectrophotometric methods have been developed for the assay of trazodone hydrochloride (TRH) in pure and pharmaceutical formulations. These methods are based on the formation of chloroform soluble ion-association complexes of TRH with bromothymol blue (BTB) and with bromocresol purple (BCP) in KCl-HCl buffer of pH 2.0 (for BTB) and in NaOAc-AcOH buffer of pH of 3.6 (for BCP) with absorption maximum at 423 nm and at 408 nm for BTB and BCP, respectively. Reaction conditions were optimized to obtain the maximum color intensity. The absorbance was found to increase linearly with increase in concentration of TRH, which was corroborated by the calculated correlation coefficient values (0.9996, 0.9945). The systems obeyed Beer's law in the range of 0.2-14.5 and 0.2-14.1 microg/ml for BTB and BCP, respectively. Various analytical parameters have been evaluated and the results have been validated by statistical data. No interference was observed from common excipients present in pharmaceutical formulations. The proposed methods are simple, accurate and suitable for quality control applications.