Untitled

Abstract

Two spectrophotometric methods have been described for the assay of verapamil hydrochloride in drug formulations. Method A is based on the oxidation of the drug with potassium metaperiodate in sulfuric acid medium to give colored product, which absorbs maximally at 425 nm. Method B involves the formation of colored chloroform extractable ion-pair complex of the drug with tropaeolin 000 No.1 at pH 4.0 showing absorption peak at 400 nm. Under the optimized experimental conditions, Beer' s law is obeyed in the concentration ranges of 12.5-187.5 and 2.0-30.0 µg mL -1 for methods A and B, respectively. Results of analyses were validated statistically and through recovery studies. Statistical comparison of the results with the reference method shows excellent agreement and indicates no significant difference in accuracy and precision. Both methods have been successfully applied to the determination of verapamil hydrochloride in drug formulations.

A Kinetic spectrophotometric method for determination of amlodipine and Nifedipine in pharmaceutical preparations

“…The proposed kinetic method was fast and resulted in dynamic ranges and detection limits better or comparable with the existing spectrophotometric methods based on oxidation of drugs [22][23][37][38]. The method was applied to the analysis of pharmaceutical preparations containing AML or NIF, successfully.…”

“…The calculated detection limits for AML and NIF were 0.10 and 0.19 Pg ml -1 , respectively. In Table 3 are compared the linear range, detection limit and procedure time of the previously reported methods using different oxidizing agents [22][23][37][38] with those of the proposed methods for AML and NIF. As it is seen, the proposed method for AML not only represented wider in comparison with the other existing methods.…”

“…In the case of NIF, although the proposed method does not represent significant improvement for dynamic range and detection limit, it can be preferred with respect to lower measuring time or better experimental conditions. For example, the method used Fe(III)-1,10-phenanthroline as reagent [38], needs 5 min heating at 100 ºC and that used potassium hydroxide [37] was performed in dimethyl solfuxide which is not preferred for its environmental hazards.…”

“…Similarly, survey of literature for NIF revealed methods based on GC [24][25][26], different liquid chromatographic methods [27][28][29][30][31][32], and stripping voltammetry [33,34]. There are also some equilibrium visible spectrophotometric methods for NIF that are based on oxidation or reduction of the drug, where reactions products are colored [35][36][37][38]. Surprisingly, according to the best of our knowledge, no kinetic spectrophotometric method has been reported for the quantitation of the DHP derivatives.…”

Detection, Isolation and Characterization of Principal Synthetic Route Indicative Impurities in Verapamil Hydrochloride

“…The different analytical techniques reported so far for the determination of this drug along with associated impurities are capillary electrophoresis [9, 10], spectrophotometry [11, 12], HPLC [13, 14], atomic emission spectrometry [15], and the Rayleigh scattering method [16]. …”