Highly Sensitive Spectrofluorimetric and Colorimetric Quantitation of Neomycin Using Nanosilver-Fluorescein Hybrid: A Comprehensive Assessment of Greenness and Blueness.

Two versatile yet simple methods, colorimetric and spectrofluorimetric, were utilized for the quantitation of nonchromophore neomycin using silver nanoparticles modified with fluorescein. Fluorescein was excited at 485 nm (emission at 515 nm); when it is deposited on the surface of silver nanoparticles, its fluorescence intensity at 515 nm is quenched. Neomycin restores the fluorescence level at 515 nm by displacing fluorescein from nanoparticle binding sites. When neomycin reacts with silver nanoparticles modified with fluorescein, it causes reduction of silver nanoparticles' plasmon resonance surface band at 395 nm and changes of the solution's color from yellow to pale pink. For the spectrofluorimetric and colorimetric techniques, the calibration graphs with a linearity range of 5-45 ng/mL and 0.5-10 μg/mL, respectively. The suggested techniques were used to determine neomycin in neomycin tablets, yielding mean recovery of 99.696 ± 0.764 and 99.925 ± 1.515 for the spectrofluorimetric and colorimetric methods, respectively. The established techniques were validated according to the ICH guidelines. Analytical greenness calculator (AGREE) along with greenness tool for sample preparation (AGREEprep) was used to evaluate how environmentally friendly the sample preparation and analytical process were. In addition, the suggested approaches' practicality is assessed using the Blue Applicability Grade Index (BAGI).