A kinetic spectrophotometric method for the determination of lansoprazole in pharmaceutical formulations

Asimple kinetic spectrophotometric method has been developed for the determination of lansoprazole in pharmaceutical formulations. The method is based on the oxidation of the drug with alkaline potassium permanganate at room temperature. The reaction was followed spectrophotometrically by measuring the increase in the absorbance owing to the formation of MnO42- at 610 nm (Method A) and the decrease in the absorbance at 530 nm due to the disapperance of MnO4- (Method B). Calibration procedures were adopted for the assay of the drug. The calibration curves were linear over the concentration ranges of 5 – 150 and 5 – 70 mg ml-1, with the corresponding calibration Equations: rate = –3.915 × 10-6 + 5.271 × 10-5 c and DA = 1.04 × 10-3 + 1.78 × 10-3 c for methods A, and B, respectively. A statistical comparison of the results of the proposed procedures with those of the reference spectrophotometric method show excellent agreement and indicated no significant difference between the compared methods in terms of accuracy and precision. Interval hypothesis tests were also performed, which indicated that the true bias of all samples was less than ± 2 %.