Green Sequential UV-Spectrophotometric Estimation Method for Nintedanib and Docetaxel in Nanocarriers

Objective: The present study aimed to develop and validate a novel, green sequential ultraviolet-visible (UV-Vis) spectrophotometric subtraction method for the simultaneous estimation of nintedanib (NTB) and docetaxel (DTX) in hybrid lipid-polymer nanoparticles. Methods: The nanocarriers were formulated using a single emulsion solvent evaporation technique utilizing poly(lactic-co-glycolic acid), soy lecithin, and D-α-tocopheryl polyethylene glycol 1000 succinate. To resolve the spectral overlap of the two therapeutics, a sequential mathematical approach was developed utilizing the absolute spectral independence of NTB at 385.6 nm and the predictable overlap at 230.0 nm. The method was validated strictly according to ICH Q2(R1) guidelines. Method greenness was evaluated using AGREE and ComplexGAPI metrics. Results: The method demonstrated excellent linearity (R² ≥ 0.9999) across 5.0–20.0 µg/ml for NTB (at 385.6 nm) and 5.0–35.0 µg/ml for DTX (at 230.0 nm). Precision was confirmed with relative standard deviations<2%. Statistical evaluation via a one-sample t-test confirmed high accuracy with mean recoveries near 100% (p>0.05). Application of the method to the formulated hybrid nanoparticles revealed highly efficient dual-drug encapsulation (>84%). Green metric assessments confirmed an excellent environmental profile (AGREE score 0.69) with minimal waste generation. Conclusion: The validated sequential subtraction method provides a highly accurate, reproducible, and eco-friendly analytical framework, successfully overcoming the limitations of traditional iso-absorptive techniques for the simultaneous quantification of NTB and DTX in complex nano-matrices.