Analysis of domperidone in pharmaceutical formulations and wastewater by differential pulse voltammetry at a glassy-carbon electrode

Spectrophotometric methods manipulating ratio spectra for simultaneous determination of binary mixtures with sever overlapping spectra: a comparative study

Three simple, specific and accurate spectrophotometric methods manipulating ratio spectra were developed and validated for simultaneous determination of Rabeprazole sodium (RB) and Domperidone (DP) in their binary mixture without prior separation. Method A, is constant center spectrophotometric method (CC). Method B is a ratio difference spectrophotometric one (RD), while method C is a combined ratio isoabsorptive point-ratio difference method (RIRD). Linear correlations were obtained in range of 4-44μg/mL for both Rabeprazole sodium and Domperidone. The mean percentage recoveries of RB were 99.69±0.504 for method A, 99.83±0.483 for (B) and 100.31±0.499 for (C), respectively, and that of DP were 99.52±0.474 for method A, 100.12±0.505 for (B) and 100.16±0.498 for (C), respectively. Specificity was investigated by analysis of laboratory prepared mixtures containing the cited drugs and their combined tablet dosage form. The obtained results were statistically compared with those obtained by the reported methods, showing no significant difference with respect to accuracy and precision. The three methods were validated as per ICH guidelines and can be applied for routine analysis in quality control laboratories.

Analysis of spironolactone residues in industrial wastewater and in drug formulations by cathodic stripping voltammetry

The redox behavior of spironolactone (SP) drug in Britton–Robinson (BR) buffer of pH 2–11 was investigated by differential pulse cathodic stripping voltammetry (DPCSV) and cyclic voltammetry (CV) at hanging mercury dropping electrode (HMDE). At pH 9–10.5, the DPCSV of SP drug showed two cathodic peaks at −1.15 and −1.38 V at the HMDE vs. Ag/AgCl reference electrode. In the CV, at pH 9–10, the dependence of the cathodic peak current, I_p,_c and peak potential, E_p,c of the second peak (E_p,c2) on the scan rate (ν) and on the depolizer (SP) concentrations was typical of an electrode coupled (EC) chemical reaction type mechanism. The plot of I_p,_c at −1.380 V of the DPCSV vs. SP concentration at pH 9 was linear over the concentration range of 1.2×10⁻¹⁰−9.6×10⁻⁷ M. The lower limit of detection (LLOD) and limit of quantification (LOQ) of the drug were 1.1×10⁻¹¹ and 4.14×10⁻¹¹ M, respectively. The method was successfully applied for the analysis of SP residues in industrial wastewater, in pure form (98.2±3.1%) and in drug formulations e.g. Aldactone® tablet (98.35±2.9%).The method was validated by comparison with HPLC and the official data methods.

Stripping voltammetric behaviour of toxic drug nitrofurantoin

A simple, sensitive and reproducible squarewave cathodic adsorptive stripping voltammetric method has been developed for the determination of nitrofurantoin in solubilized system. The objective of the present paper is to investigate the redox behaviour of nitrofurantoin by using different voltammetric techniques and to establish the methodology for its determination in the presence of surfactants. Voltammograms of the drug with cetrimide in phosphate buffers of pH 2-11 exhibited a single well-defined reduction peak which may be attributed to the reduction of -NO(2) group. The reduction process is irreversible over the entire pH range studied. The mechanism of reduction has been postulated on the basis of controlled potential electrolysis, coulometry and spectral analysis. The proposed SWCAdSV voltammetric method allows the determination of nitrofurantoin in linear concentration range 2 x 10(-5) to 1 x 10(-7) mol L(-1). The lower limit of detection (LOD) and lower limit of quantification (LOQ) are 0.06 and 0.27 ng/mL, respectively.