Two simple and sensitive extractive spectrophotometric methods have been described for the assay of Lansoprazole (LPZ) either in pure form or in pharmaceutical formulations. The methods were based on the formation of ion-pair complex between LPZ and Metanil Yellow (MY) – Method- A and methyl orange (MO)- Method- B, at pH 2.5 has been described. The formed complex were extracted quantitatively into chloroform and measured at 440 nm and 450 nm with MY and MO respectively. Beer's law was obeyed in the concentration range of 20-70 µg mL-1 and 6-16 µg mL-1 with molar absorptivity of 1.329 x 10-8 and 1.822 x 10-8 L mol-1 cm-1 with MY and MO respectively. Statistical comparison of the results of the proposed method with those of the reference method shows excellent agreement and indicates no significant difference in accuracy and precision. The limits of detection and quantification have been determined for two methods. Both the methods have been validated as per the guidelines of ICH. The methods have been applied to the determination of drug in commercial capsules and results of analysis were validated statistically through recovery studies.
Extractive spectrophotometric, Lansoprazole, Metanil Yellow, Methyl Orange.