Sustainable signal-processing spectrophotometric approaches for synchronous analysis of novel antiallergic combination: evaluation via multi-metric sustainability indices

Abstract This study presents the development and validation of six sustainable signal-processing spectrophotometric approaches designed for the synchronous analysis of a novel antiallergic combination: Doxylamine succinate (DOX) and Phenylephrine hydrochloride (PHE). To resolve spectral overlap without chemical separation, various mathematical frameworks were employed, including: dual wavelength (DW), fourier self-deconvolution (FSD), first derivative (D 1 ), derivative ratio (DD 1 ), amplitude modulation (AM), and the amplitude summation (A-sum) method. The analytical procedures were conducted within linear ranges of 8.0–56.0 µg/mL for DOX and 20.0–180.0 µg/mL for PHE. Several processing parameters and wavelengths selection were optimized for each approach. DW approach is utilized ΔA 263.0–284.0 for DOX and ΔA 274.0–254.0 for PHE. The FSD method is applied at 286.0 for DOX and 278.0 nm for PHE. While D 1 amplitude is measured at 273.0 and 263.0 nm for DOX and PHE, respectively. The DD 1 approach utilized 237.0 nm for DOX and 287.0 nm for PHE. AM method was carried out at 277.0 nm while, A- sum method was applied at 288.0 nm for estimation of both DOX and PHE. All six methodologies showed excellent accuracy and precision according to ICH guidelines. Statistical comparison with established reference methods revealed no significant differences in performance. The environmental and practical impact of the methods was evaluated via multi-metric sustainability modern tools. The analytical greenness metric for sample preparation, the spider method, the green solvent selection too, Blue Applicability Grade Index, Click Analytical Chemistry Index, and Violet Innovation Grade Index were among the twelve newly created assessment metrics. Additionally, the Carbon Footprint Reduction Index, the Analytical Green Star Area, the Sustainability of Analytical Methods Index, the Modified GAPI, the Whiteness Evaluation for Chemical Analysis, and the Analytical Method Reliability Index. The results demonstrate that these signal-processing approaches offer a highly efficient, eco-friendly, and cost-effective alternative for the quality control of DOX and PHE in both raw materials and commercial tablets.