Visible spectrophotometry

Four simple, accurate and highly sensitive spectrophotometric methods have been developed for the determination of Lansoprazole in both pure and in pharmaceutical preparations. The method A andB  are based on the ion associationcomplex formation between Lansoprazole and Supracen Violet 3B (method A) or Tropaeolin OOO (method B)  the third and fourth are indirect methods where the drug is oxidsed by a known excess of Chloramine T and determining the consumed Chloramine T with decrease in colour intensity of the dye Gallocyanine (method C ) or oxidation with excess of N-Bromosuccunimide in acid medium. followed by the determination of unreacted N-Bromosuccunimide with the dye Celestin Blue - (method D) .Regreesion analysis of Beer’s law plots showed good correlation in the concentration range of  5.0 - 40 μg ml−1, 5.0 -25 μg ml−1 , 2.5 – 12.5 μg ml−1, 1.0 – 6.0μg ml−1 for methods A, B ,C and D respectively, and the corresponding molar absorptivity values are 0.9232 x 104 , 1.0857 x 104 , 7.0997 x 104 and 2.3265 x 104 1mol−1cm−1. All variables have been optimized and the results were statistically compared with those of literature methods by employing the student’s t-test and F-test. No interference was observed from excipients normally added to the tablets.