ABSTRACT
A simple and sensitive kinetic spectrophotometric method for the determination of perindopril in pharmaceutical preparations is described. The method is based on the interaction of drug with 1-chloro-2,4-dinitrobenzene (CDNB) in dimethylsulfoxide (DMSO) at 40+/-1 degrees C. The reaction is followed spectrophotometrically by measuring the rate of change of the absorbance at 420 nm. Under the optimized experimental conditions, the calibration curve showed a linear relationship over the concentration range of 20-140 microg/ml. The activation parameter such as E(a), deltaH*, deltaS* and deltaG* for this reaction were calculated and found to be 27.31 kJ/mol, 24.69 kJ/mol, -138.84 J/K/mol and 61.50 kJ/mol, respectively. The method has been successfully applied to the determination of perindopril in commercial dosage forms. Statistical comparison of the results with the Abdellatef's spectrophotometric method shows excellent agreement and indicates no significant difference between the methods compared in terms of accuracy and precision.
Subject(s)
Angiotensin-Converting Enzyme Inhibitors/analysis , Perindopril/analysis , Algorithms , Angiotensin-Converting Enzyme Inhibitors/administration & dosage , Chemistry, Pharmaceutical , Dimethyl Sulfoxide , Dinitrochlorobenzene , Indicators and Reagents , Perindopril/administration & dosage , Reference Standards , Reproducibility of Results , Tablets , ThermodynamicsABSTRACT
A simple and sensitive kinetic spectrophotometric method has been developed. The method is based on the reduction of Fe(III) with captopril. Fe(II) then reacts with potassium ferricyanide, resulting in the formation of a blue product. The reaction is followed spectrophotometrically by measuring the rate of change of absorbance at 730 nm. Thus, 1.23 x 10(-3) mol L(-1) FeCl3 and 3.04 x 10(-4) mol L(-1) potassium ferricyanide were used as optimum values for maximum concentration of captopril in the calibration graph. The initial rate is utilized for constructing the calibration graph, which was found to be linear in the range from 4.60 x 10(-6) to 5.06 x 10(-5) mol L(-1); detection limit is 1.99 x 10(-7) mol L(-1). The proposed method has been validated; the mean recovery ranges from 99.8 to 101.4% with RSD < 2%. Common excipients do not interfere with the determination. The point and interval hypotheses tests have been performed and confirmed that there is no significant difference between the proposed method and the conventional spectrophotometric method. The experimental true bias of all samples is lower than +/- 2%. The proposed method has been applied to the determination of captopril in bulk and dosage forms.
Subject(s)
Angiotensin-Converting Enzyme Inhibitors/analysis , Captopril/analysis , Spectrophotometry/methods , Excipients/chemistry , TabletsABSTRACT
Two simple, rapid and sensitive spectrophotometric methods have been proposed for the determination of lisinopril in pure form and pharmaceutical formulations. The methods are based on the charge transfer complexation reaction of the drug with 7,7,8,8,tetracyanoquinodimethane (TCNQ) and p-chloranilic acid (pCA) in polar media. The lisinopril-TCNQ and lisinopril-pCA charge transfer complexes dissociate in acetone and methanol, respectively, and yield coloured TCNQ and pCA radical anions which are measured spectrophotometrically at 743 and 525 nm. Under optimised experimental conditions, Beer's law is obeyed in the concentration range of 2-26 and 25-300 microg ml-1 with molar absorptivity of 1.432x10(4) and 1.192x10(4) l mol-1 cm-1 for TCNQ and pCA methods, respectively. Both the methods have been applied to the determination of lisinopril in pharmaceutical dosage forms. Results of analysis are validated statistically.
