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Kinetic spectrophotometric determination of simvastatin using alkaline potassium permanganate

Shereen Mowaka, Sherif A.Abdel-Gawad

Two simple and sensitive kinetic spectrophotometric methods were established for the determination of simvastatin (SIM) in pure and dosage forms using alkaline potassium permanganate as an oxidant. The investigated methods involve the determination of SIMby kinetic study of its oxidation reaction at roomtemperature for a fixed time of 20 minutes and 10 minutes for the first and second methods, respectively. In the first method, the absorbance of the produced manganate was measured at 610 nm, while in the second method the reduction in the absorbance of permanganate was measured at 525 nm. The absorbance-concentration plots were rectilinear over the concentration range of 3.0-30.0 ìg/mL in the firstmethod and 3.0- 25.0 ìg/mL in the second method with detection limits of 1.0 ìg/mL in both methods. The proposed methods were applied successfully for determination of SIM in pure and dosage forms. The proposed methods were statistically compared with a reference one showing no significant differences regarding accuracy and precision. In addition, the activation parameters such as Ea, H, S and G were also evaluated for the reaction and found to be 43.03 KJ mol-1, 45.78 KJ mol-1, 33.06 JK-1 mol-1 and -9.85 KJ mol-1, respectively.