Application of continuous wavelet transforms for simultaneous estimation of domperidone and lansoprazole in capsule formulations

UV–Vis spectroscopy remains essential in pharmaceutical research and quality control due to its accessibility, simplicity, and effectiveness. However, overlapping spectra resulting from multicomponent drug formulations present challenges. Here, we describe a signal processing strategy using continuous wavelet transform (CWT) to resolve overlapping spectra of domperidone (DMP) and lansoprazole (LSP) for simultaneous quantification. Three different wavelet functions (Symlets 3, Coiflets 1, Daubechies 10), were found to be suitable for this purpose. Linear calibration curves were constructed using the CWT zero-crossing technique and the methods were validated by analyzing a set of synthetic mixtures, intra-and inter-day samples, and standard addition samples. The assay results of commercial capsule samples were compared with those obtained by derivative spectroscopy, and no significant statistical difference was observed. The proposed CWT methods demonstrated good compliance with the label claims and proved to be reliable, versatile, fast, and cost-efficient analytical methods without the need for preliminary separation procedures.