Validation of simultaneous volumetric and spectrophotometric methods for the determination of captopril in pharmaceutical formulations

Circular Dichroism Spectroscopy: A Facile Approach for Quantitative Analysis of Captopril and Study of Its Degradation

Simple and selective zero- and second-order derivative circular dichroism (CD) spectroscopic methods have been designed for the assay of captopril in commercially available dosage forms. A normal CD spectroscopic scan (zero order) exhibits a negative band at 208 nm (method A) in distilled water. The calibration curve shows a linear response over the concentration range of 10-80 μg mL^-1. The second-order derivative (D2) CD spectrum shows one positive band at 208 nm (method B) and one negative band at 225 nm (method C). Linear calibration curves were obtained in the concentration range of 10-70 μg mL^-1 for both the methods (B and C). The detection limits were found to be 1.26, 1.48, and 2.38 μg mL^-1 for methods A, B, and C, respectively. The study under stressed acidic, basic, and oxidative conditions showed the degradation of captopril. The proposed methods were validated as per ICH guidelines. All the proposed methods were compared with the reference method to demonstrate its suitability for quality control of captopril in its dosage forms.

A surface plasmon resonance sensing method for determining captopril based on in situ formation of silver nanoparticles using ascorbic acid

A new method has been proposed to sensitive detection of captopril based on surface plasmon resonance band of silver nanoparticles (AgNPs). The stable and well-dispersed AgNPs with strong plasmon resonance signal were synthesized in situ using a simple and rapid procedure by applying ascorbic acid as reducer and sodium dodecyl sulfate as stabilizer, at room temperature. It was found that, the decreasing of AgNPs plasmon absorbance is proportional to the concentration of captopril which allows the spectrophotometric sensing of this compound. The presented method is capable of determining captopril over a range of 0.20-2.75 μmol L(-1) with a limit of detection 0.07 μmol L(-1). The relative standard deviation for eight replicate measurements of 1.00 and 2.50 μmol L(-1) of captopril was 2.37% and 1.02%, respectively. The method was applied to the determination of captopril in pharmaceutical formulations with satisfactory results, which were in agreement with those of the official method.

Highly Improved Electrooxidation of Captopril on Copper Hexacyanoferrate/Ordered Mesoporous Carbon-Modified Glassy Carbon Electrode

Using an electrochemical polymerization process, a copper hexacyanoferrate/ordered mesoporous carbon-modified glassy carbon electrode (CuHCF/OMC/GCE) was prepared. The performance of CuHCF/OMC was compared with that of CuHCF and the properties of the new material were improved. A sensor for sensitive detection of captopril was developed based on CuHCF/OMC-modified glassy carbon electrode. The composition and morphology of the as-prepared CuHCF/OMC products were characterized by energy-dispersive X-ray spectroscopy and scanning electron microscopy. The electrochemical behaviour and electrocatalytic performance of the CuHCF/OMC-modified glassy carbon electrode towards the oxidation of captopril were evaluated by cyclic voltammetry. Results showed that the CuHCF/OMC-modified electrode exhibits two well-defined redox peaks. The linear range for the detection of captopril was from 1.0 × 10–5 to 2.7 × 10–3 M, with a correlation coefficient of 0.999, and the detection limit was 1.2 × 10–6 M based on a signal-to-noise ratio of 3.

Spectral characteristic investigation on complex of Ni (II) with captopril and its analytical application

In this paper, Ni (II) reacting with captopril (CPT) can form complex in alkaline solution and the formed complex has a characteristic absorption peak at 340nm. The absorbance of the Ni-CPT complex increases linearly with the increased concentration of captopril. The study also shows that ammonia has an obvious sensitizing effect on the absorbance. Based on the study, a new method for the determination of captopril is established. Experimental results show that the linear range of this method under optimum condition is 1.0-60mg/L with correlation coefficient, detection limit and precision of 0.9999, 0.31mg/L and 0.87%, respectively. The method used to determine captopril in commercial captopril tablets has a satisfactory result with the recoveries in the range of 99.0-103.6% and the relative standard deviation (RSD) in the range of 0.8-3.7%. We preliminarily study the reaction mechanism and demonstrate that the complex ratio of Ni (II) with captopril is 1:2 and the formation constant is 6.3×10(9).

Simultaneous determination of captopril and hydrochlorothiazide by time-resolved chemiluminescence with artificial neural network calibration

The combined use of chemometrics and chemiluminescence (CL) measurements, with the aid of the stopped-flow mixing technique, developed a simple time-resolved CL method for the simultaneous determination of captopril (CPL) and hydrochlorothiazide (HCT). The stopped-flow technique in a continuous-flow system was employed in this work in order to emphasize the kinetic differences between the two analytes in cerium (IV)-rhodamine 6G CL system. After the flow was stopped, an initial rise of CL signal was observed for HCT standards, while a direct decay of CL signal was obtained for CPL standards. The mixed CL signal was monitored and recorded on the whole process of continuousflow/stopped-flow, and the obtained data were processed by the chemometric approach of artificial neural network. The relative prediction error (RPE) of CPL and HCT was 5.9% and 8.7%, respectively. The recoveries of CPL and HCT in tablets were found to fall in the range between 95% and 106%. The proposed method was successfully applied to the simultaneous determination of CPL and HCT in a compound pharmaceutical formulation.