Titrimetric and Spectrophotometric Assay of Diethylcarbamazine Citrate in Pharmaceuticals using Permanganate as Oxidant

Abstract

Two titrimetric and one spectrophotometric methods are described for the determination of diethylcarbamazine citrate in bulk drug and dosage forms using permanganate as an oxidimetric agent. In method A, the drug solution in H₂SO₄ is titrated directly at 80°C to a pink end-point. DEC was treated with a measured excess of standard permanganate in H₂SO₄ medium, and after a contact time of 5 min, the residual oxidant back titrated with ammonium ferrous sulphate to a colorless end-point (method B). Spectrophotometry is based on the measurement of the unreacted permanganate at 550 nm after the reaction between DEC and permanganate in H₂SO₄ medium is ensured to be complete (method C). In all methods, the amount of permanganate reacted was related to the amount/concentration of DEC. Experimental variables associated with the assay were carefully examined and optimized for better performance characteristics. Both the titrimetric methods are applicable over 1–10 mg range and the reaction follows 1:3 and 1:4 (DEC:KMnO₄) stoichiometry in direct and indirect methods, respectively. In spectrophotometry, Beer's law is obeyed in the inverse manner, and linearity is observed in the range 2.5–30 µg ml^-1 with a molar absorptivity value of 8.03×10³ l mol^-1 cm^-1. The limits of detection (LOD) and quantification (LOQ) were calculated to be 0.12 and 0.35 µg ml^-1, respectively. The methods were validated for precision and accuracy, robustness and ruggedness and selectivity. The methods were applied to the determination of DEC in tablets and suspension with satisfactory results. The accuracy of the methods was also assessed by recovery study via standard-addition procedure.

Keywords: Diethylcarbamazine citrate, assay, titrimetry, spectrophotometry, permanganate, pharmaceuticals

Cite this Article

Nagib Qarah AS, Basavaiah K. Titrimetric and Spectrophotometric Assay of Diethylcarbamazine Citrate in Pharmaceuticals using Permanganate as Oxidant. Research and Reviews: A Journal of Pharmaceutical Science. 2016; 7(3): 1–11p.