“…On the other hand, the absorption bands at 3650–3600 cm −1 (H-bonded OH groups), 2940–2900 cm −1 (aliphatic C–H stretching), 1720–1700 cm −1 (C–O stretching and COOH-OH deformation), and 1099 cm −1 (polysaccharide C–O stretching or silicate impurity Si–O stretching) were particularly noticeable in the pure FA, whereas in the FTIR spectra of the lyophilized NE (KBr), the bands were observed at 3398.72 (-OH), 3289.74 (-OH), 2905.89 (C-H, stretching), 2292 (O=C=O, stretching), 2058.13 (C-H, bending), 1738.90 (C=O, ester), 1648.24 (C=O, stretching), 1424.49 (C-H bending, methyl), 1287.54 (C-H, rocking), 1083.08 (-C-O), 928.76 (C-H wagging, alkene), and 874.76 cm −1 (C=C, bending). Collectively, a slight shift in the peaks was observed in the spectra of the lyophilized NE as compared to the pure drug and fulvic acid, thus indicating its amalgamated/complexed nature [ 41 ]. In the case of the mannitol (cryoprotectant), the peaks were very close to the NE spectra, as it was used in excess to ensure an effective lyophilization of the NE.…”