New spectroscopic methods for determination of dexlansoprazole using mercurochrome

New spectroscopic methods were developed for dexlansoprazole estimation in capsule formulation based on the formation of a reaction between dexlansoprazole and Mercurochrome (MER) at pH 3.7. The formed complex was measured spectrophotometrically (Method I) at 557 nm and spectrofluorometrically (Method II) at 300 nm/538 nm, because the drug caused quantitative quenching of the native fluorescence of Mercurochrome. The spectrophotometric method was linear over the concentration 25-55 μg/ml with a limit of detection (LOD) of 1.15 μg/ml and a limit of quantification (LOQ) of 3.48 μg/ml. The spectrofluorometric method had a linear range 20-45 μg/ml with an LOD of 1.13 μg/ml and an LOQ of 3.45 μg/ml. The suggested methods were used to analyze capsules to test the interference from excipients and the data indicated good selectivity. Data obtained were statistically analyzed and were favourably good. The new methods are environmentally benign and depend on distilled water mainly as the diluting solvent. This property was confirmed by assessing their greenness.